Power receiver electronics

Abstract

A power receiver includes a plurality of photovoltaic (PV) cells, each PV cell having an active surface configured to receive light for conversion to electrical power, and a cathode connector and an anode connector configured to generate a voltage therebetween when the active surface of the PV cell is exposed to light.SOLUTION: The free space power receiver includes a layout of photovoltaic cells selected to optimize power extraction even as the power beam moves or changes profile on the receiver. The receiver may also include a circuit board having an opening therein to allow light to reach the photovoltaic cell. The circuit board may include appropriate wiring for connecting the photovoltaic cells to each other and to a load for power extraction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63 / 140,256, filed January 22, 2021, and U.S. Provisional Patent Application No. 63 / 286,516, filed December 6, 2021, each of which is incorporated by reference herein to the extent not inconsistent herewith. [Background technology]

[0002] Power beaming is an emerging method of transmitting power to locations that are difficult or inconvenient to access using wires (or electrical cables) by sending a beam of electromagnetic energy to a specially designed receiver that converts it into electricity. Power beaming systems can be free-space power (FSP), in which the beam is sent through air, vacuum, liquid, or other non-optically designed medium, or power-over-fiber (PoF), in which power is transmitted over optical fiber. While the latter may share certain drawbacks with wires in some situations, they may also offer improved transmission efficiency, electrical isolation, safety, and / or reduced mass. FSP may be more flexible but may present more challenges in precisely targeting the receiver and avoiding hazards such as reflections and objects that intersect the power beam. DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0003] All of the subject matter discussed in the "Background" section is not necessarily prior art and should not be assumed to be prior art merely as a result of its discussion in the "Background" section. Along these lines, recognition of problems in the prior art discussed in the Background section or related to such subject matter should not be treated as prior art unless expressly stated to be prior art. Instead, the discussion of any subject matter in the Background section should be treated as part of the inventors' approach to a particular problem and may itself be inventive. [Means for solving the problem]

[0004] In one aspect, a power receiver includes a plurality of photovoltaic (PV) cells, each PV cell having an active surface configured to receive light for conversion to electrical power and a cathode connector and an anode connector configured to generate a voltage therebetween when the active surface of the PV cell is exposed to light. The receiver further includes a circuit board connected to at least one of the cathode connector and the anode connector, the circuit board having a plurality of openings therein and an output connector configured to electrically connect the circuit board to a load. Each PV cell is positioned to receive light that has passed through at least one of the plurality of openings in the circuit board.

[0005] In another aspect, a power receiver includes a plurality of photovoltaic (PV) cells disposed on a support surface, the PV cells being divided into a plurality of voltage groups, each voltage group having a selected output voltage and output current, and electrical wiring for interconnecting the PV cells, the wiring being configured to connect each PV cell in a voltage group in parallel and to connect each voltage group in series to at least one other voltage group. The PV cells in each voltage group are disposed discontinuously with one another on the support surface, and the plurality of voltage groups exhibit a current mismatch (or mismatch) of less than 5%, where current mismatch is defined as the difference between the maximum and minimum output currents divided by the average output current when the receiver is exposed to a power beam.

[0006] In another aspect, a power receiver includes a plurality of photovoltaic (PV) cells arranged on a support surface to form a PV array, the PV cells being divided into a plurality of voltage groups, each voltage group having a selected output voltage and output current, and electrical wiring for interconnecting the PV cells. The wiring is configured to connect each PV cell in a voltage group in parallel and to connect each voltage group in series to at least one other voltage group. The PV cells in each voltage group are arranged in a repeating pattern along a first axis of the PV array, and the repeating pattern is staggered along a second axis of the PV array by an offset value selected to prevent PV cells in the same voltage group from being adjacent to each other.

[0007] In another aspect, a power receiver includes a plurality of photovoltaic (PV) cells arranged on a support surface to form a PV array, the PV cells being divided into a plurality of voltage groups, each voltage group having a selected output voltage and output current, and electrical wiring for interconnecting the PV cells, the wiring being configured to connect each PV cell in a voltage group in parallel and to connect each voltage group in series to at least one other voltage group, and each voltage group having a property that a Voronoi diagram of the positions of the PV cells in the voltage group has a median Voronoi cell aspect ratio of less than 1.4.

[0008] In another aspect, a power receiver includes a plurality of photovoltaic (PV) cells, a circuit board having a plurality of openings therein, and an output connector. Each PV cell has an active surface configured to receive light for conversion to electrical power, and a cathode connector and an anode connector configured to generate a voltage therebetween when the active surface of the PV cell is exposed to light. The circuit board is connected to at least one of the cathode connector and the anode connector, and the output connector is configured to electrically connect the circuit board to a load. Each PV cell of the plurality is positioned to receive light that has passed through at least one of the openings in the circuit board.

[0009] In another aspect, a power receiver includes a heat sink including a first side, a second side, and an opening passing from the first side to the second side, a current collecting device in thermal contact with the first side of the heat sink, an electronic component disposed on the second side of the heat sink, and an electrical connector disposed within the opening in the heat sink, the electrical connector connecting the current collecting device to the electronic component.

[0010] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Moreover, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. [Brief explanation of the drawings]

[0011] The drawings illustrate one or more implementations in accordance with the present teachings by way of example only, and not by way of limitation. In the drawings, like reference numbers refer to the same or similar elements. Additionally, it should be understood that the drawings are not necessarily to scale.

[0012] [Figure 1]FIG. 1 is a schematic diagram of a power beaming transmitter and receiver.

[0013] [Figure 2] FIG. 2 is a schematic diagram of the power beaming transmitter of FIG. 1, showing the interrelationships between the transmitter components.

[0014] [Figure 3] FIG. 3 is a schematic diagram of the power receiver of FIG. 1, showing the interrelationships between the components of the power receiver.

[0015] [Figure 4(a)] FIG. 4(a) is a schematic diagram of a power receiver geometry that includes a circuit board with an opening therein.

[0016] [Figure 4(b)] FIG. 4(b) shows the power receiver of FIG. 4(a) from the side.

[0017] [Figure 5] FIG. 5 is a schematic diagram of the geometry of a power receiver in combination with a concentrator.

[0018] [Figure 6] FIG. 6 is a diagram of a power receiver with a perforated heat sink.

[0019] [Figure 7] 7a and 7b, collectively referred to herein as FIG. 7, illustrate top and bottom views of another power receiver embodiment including a perforated vapor chamber.

[0020] [Figure 8] Figure 8 is a wiring diagram of a PV array.

[0021] [Figure 9(a)] FIG. 9(a) shows the PV cell layout of FIG. 3 in Kare.

[0022] [Figure 9(b)] Figure 9(b) shows Kare's PV cell layout of Figure 5, "doubled" by placing two copies of Kare's depicted array side by side.

[0023] [Figure 10] FIG. 10 shows the Voronoi mesh for one voltage level of the array of FIG. 9(b) and a histogram of the aspect ratio of the illustrated mesh.

[0024] [Figure 11] FIG. 11 shows a PV array of approximately the same size and shape as in FIG. 9(b), with a model beam profile.

[0025] [Figure 12] FIG. 12 shows the Voronoi mesh for one voltage level of the array of FIG. 11, along with a histogram of the aspect ratio of the illustrated mesh.

[0026] [Figure 13] FIG. 13 shows a Voronoi mesh corresponding to the mesh shown in FIG. 10, but with an expanded number of cells.

[0027] [Figure 14] FIG. 14 shows a Voronoi mesh corresponding to the mesh shown in FIG. 12, but with an expanded number of cells.

[0028] [Figure 15] Figure 15 shows a square PV array layout showing the voltage level of each cell, with the beam profile superimposed.

[0029] [Figure 16] FIG. 16 shows a Voronoi mesh of cells at one voltage level in the array of FIG. 15, along with a histogram of the aspect ratios of the mesh shown.

[0030] [Figure 17] FIG. 17 shows a PV array layout having an approximately octagonal shape.

[0031] [Figure 18] FIG. 18 shows a model beam profile for application to the array of FIG. 9(a).

[0032] [Figure 19] FIG. 19 shows the modeled level currents for the array shown in FIG. 9(a).

[0033] [Figure 20] FIG. 20 shows a model beam profile for application to the array of FIG. 9(b).

[0034] [Figure 21] FIG. 21 shows the modeled level currents for the array shown in FIG. 9(b).

[0035] [Figure 22] FIG. 22 shows the modeled level currents for the array shown in FIG.

[0036] [Figure 23] FIG. 23 shows the modeled level currents for the array shown in FIG.

[0037] [Figure 24] FIG. 24 shows the modeled level currents for the array shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0038] In the following detailed description, numerous specific details are set forth by way of example to provide a thorough understanding of the relevant teachings. However, it will be apparent that the present teachings may be practiced without such details. In other instances, well-known methods, procedures, components, and / or circuits have been described at a relatively high level, without detail, to avoid unnecessarily obscuring aspects of the present teachings. Nevertheless, those skilled in the art will understand the features of these methods, procedures, components, and / or circuits and how they may be used in the following description. Other relevant material may be found in other patents and applications, as follows: TIFF2026016446000002.tif231169 Each of these related applications and patents is incorporated herein by reference to the extent not inconsistent herewith.

[0039] As mentioned above, power beaming is becoming a viable method of delivering power to objects in situations where running wires is inconvenient or difficult. For example, free-space power beaming can be used to deliver power via a ground-based power transmitter to power remote sensors, recharge batteries, or power unmanned aerial vehicles (UAVs) such as dronecopters, allowing them to remain airborne for extended periods of time. Power-over-fiber (PoF) systems typically require optical fiber (or equivalent) to be run from the power source to the receiver, but may offer electrical isolation and / or other advantages over traditional copper wire, which carries electricity instead of light.

[0040] It will be understood that the term “light source” is intended to encompass all forms of electromagnetic radiation that can be used to transfer energy, not just visible light. For example, a light source (e.g., a diode laser, fiber laser, light-emitting diode, magnetron, or klystron) can emit ultraviolet, visible, infrared, millimeter-wave, microwave, radio wave, and / or other electromagnetic waves, any of which may be generally referred to herein as “light.” The term “power beam” is used interchangeably with “light beam” herein and generally refers to an inherently directional, high-irradiance transmission, which may be of a single wavelength or multiple wavelengths, coherent or incoherent, and pulsed or continuous. The power beam may be free-space, PoF, or may include each component. For example, a transmitter can transmit a free-space power beam to a receiver surface, which may conduct it as light over an optical fiber to a photovoltaic (PV) cell that converts it to electricity. For ease of reading, the description may use the term "laser" to describe the light source, although other light sources such as (but not limited to) light emitting diodes, magnetrons, or klystrons may nevertheless be contemplated unless the context dictates otherwise.

[0041] In many applications, a power receiver is configured to receive a free-space or PoF power beam and convert it to electricity, for example, using a PV cell or other component for converting light to electricity (e.g., a rectenna for converting microwave power, or a heat engine for converting heat generated by the light beam to electricity). For ease of reading, this application may refer to a "PV cell" with the understanding that other components having similar functionality (such as, but not limited to, those listed above) may be substituted without departing from the scope of this application. <Power beaming system>

[0042] FIG. 1 is a schematic diagram of a power beam transmitter 102 and receiver 104. A laser 106 directs a power beam 108 (shown as a dotted line throughout the figure) to an optical unit 110, which directs the beam to a beam steering assembly, such as a mirror assembly 112. The optical unit 110 may include various lenses, mirrors, and other optical elements, as described further below. The steering mirror assembly 112 directs the power beam 108 to the power receiver 104. An optional chiller 114 is shown connected to the laser 106, although other components of the transmitter 102 may also have separate or connected thermal management systems, as desired. FIG. 1 also shows a tracking system 116 and a safety system 118 as part of the transmitter 102. While these systems are shown in the figures as being internal to the optical unit 110, those skilled in the art will recognize that in some implementations, they may be external to the optical unit 110, part of the steering mirror assembly 112, or elsewhere in the transmitter system. Also shown are a TX controller 120, a user interface 122, and a TX communications unit 124, all of which are further described below in connection with FIG. 2. It will be understood that the transmitter 102 may include other elements, such as a beam shaper, guard beams, or other suitable accessory elements, that are omitted from FIG. 1 for simplicity of illustration. Some of these elements are shown schematically in FIG. 2 below, but those skilled in the art will understand how to combine optical and control elements within a power transmitter.

[0043] The receiver 104 in FIG. 3 includes a PV array 130, which includes a plurality of individual PV cells 132 (not all PV cells are labeled to avoid unnecessarily cluttering the figure). The PV cells 132 convert the input power beam 108 into electricity, as described further below. The receiver 104 also shows a tracking emitter 134, which in some implementations may be used by a tracking system 116 to monitor the position of the PV array 130 for beam tracking or other purposes. The receiver 104 also shows a safety emitter 136, which in some implementations may be used by a safety system 118 to monitor the power beam 108 for potential intrusion, reflection, or other safety hazards. The RX communication unit 138 (as indicated by the dashed line) communicates with the TX communication unit 124 and may be used for safety, tracking, telemetry, feedback control, or any other purpose for which it may be desirable for the transmitter 102 and receiver 104 to communicate. While the illustrated embodiment provides communication over a separate channel, such as a wireless link, between the transmitter 102 and the receiver 104, it is also contemplated that communication may be achieved via modulation of the power beam 108, tracking emitter 134, safety emitter 136, or other existing components of the power beaming system. The receiver 104 may also include an optional RX sensor 140, which is described further below in connection with FIG. 3. As shown in FIG. 1, the PV array 130 is mounted to an optional mast 142, which may elevate the receiver 104 to allow the power beam 108 to avoid people or other obstacles.

[0044] Figure 2 is a schematic diagram illustrating the functional relationships between transmitter components. Transmitter 102 includes laser 106, although it will be understood that, depending on the implementation, other light-generating components, such as an LED or magnetron, may be used in place of laser 106. Laser 106 is connected to controller 120, power supply unit (PSU) 202 (which is connected to input power 204), and thermal management system (chiller) 114. Throughout Figures 2 and 3, heat flow is indicated by thick dotted lines, power beam 108 is indicated by thick solid lines, sensor signals are indicated by thick dashed lines, data and / or control signals are indicated by dash-dot lines, and power is indicated by thin solid lines. For clarity, not all of the internal electrical connections are shown.

[0045] The controller 120 controls the operation of the laser 106 and may be manual (e.g., using a user interface 122), partially automated, or fully automated, depending on the system's design constraints. In particular, the controller 120 may receive input from a safety system, such as those described in commonly owned U.S. Patent Nos. 10,634,813 and 10,816,694, U.S. Patent Application Nos. 15,574,659 and 16 / 079,073, International Patent Application No. PCT / US20 / 34104, and U.S. Provisional Application No. 63 / 140,236. The safety system may be designed, for example, to attenuate (or turn down) or shut off (or turn off) the beam when an uninterrupted optical path from the transmitter 102 to the receiver 104 cannot be guaranteed or when other unsafe conditions may be associated with the continuation of the beam power. The controller 120 may also receive input (data) from other components, for example, to monitor the health or temperature of the laser. PSU 202 draws power from input power 204, which may be, for example, a power grid, a generator, or a battery, and provides it to laser 106. While controller 120 and chiller 114 are shown directly connected to input power 204, in other embodiments these or other components may receive power from power supply unit 202. Chiller 114 monitors the temperature of laser 106 (and / or other components of the transmitter, as needed) to ensure that it does not exceed safe values.

[0046] As shown in FIG. 2 , power beam 108 exits light source 106 and enters optical unit 110. While light 108 maintains the same reference numerals throughout FIG. 2 , it will be understood that the properties of light 108 may change in various ways (e.g., polarization, convergence / divergence angle, beam profile, or intensity) as it passes through different optical and other components. Optical unit 110 may include beam integrator 206 and other optical systems, such as lenses, mirrors, phased arrays, or any other suitable components for managing the light direction, divergence, and beam irradiance profile or for merging different optical power beams and / or signals. Beam integrator 206 is generally selected to match the wavelength range of light source 106 and may be used to modify the size, shape, or intensity distribution of the power beam. For example, when beaming power to a receiver, in some implementations it may be desirable to match the beam width to the size of the receiver and possibly "flatten" the beam irradiance profile to be relatively uniform across the surface of the receiver, e.g., converting a substantially Gaussian beam profile to a "top hat" or super-Gaussian profile. Beam direction and beam profile shaping are discussed in more detail in co-pending, commonly owned International Patent Application No. PCT / US20 / 34095. In particular, mechanisms described therein for monitoring the placement of the power beam on the receiver and using the monitored data to provide feedback to the controller 120 and / or steering assembly 112 may be incorporated into the present system.

[0047] In some implementations, the steering assembly 112 may include steering optics 210 and / or sensors 212, which may be used to measure beam characteristics, such as direction or irradiance profile, to provide feedback information for tracking the receiver and directing the beam to its location, or to monitor for potential intrusions into the optical path. The steering assembly 112 may also include merging optics. Merging optics are generally used to combine multiple optical paths, or in some cases, to separate them when the optical flow is in opposite directions. For example, as shown, the outgoing power beam 108 for transmitting power may be combined with an incoming optical beacon 208 used to track the receiver. As shown, a beacon is used in the steering assembly 112 for tracking, although in other implementations, the signal 208 may propagate through the optical unit 110 or beyond.

[0048] The transmitter 102 may also include a sensor 214 that can be used to monitor ambient conditions. The sensors 212, 214 may be used to adjust the beam integrator 206 and / or the steering optics 210. For example, the sensor 212 may monitor the position of a focusing lens or other optical component in the steering assembly 112, and the sensor 214 may be used to monitor the ambient temperature and / or the temperature of other components. Data from the sensors 212, 214 may be fed back to the controller 120 to control the steering optics 210 and / or the steering assembly 112, for example, to adjust the laser 106 for safety considerations or to direct the beam 108 onto the receiver. Control and data signals may be passed between the controller 120 and other components, as shown by the dashed-dotted lines in FIG. 2, and the controller 120 may control communications with the receiver, for example, using the transmitter communication unit 124.

[0049] After passing through the optical unit 110, the power beam 108 is directed in a desired direction away from the transmitter 102 by a steering assembly 112. In some implementations, the steering assembly 112 may include steering optics 210, motors for adjusting mirrors or other components (not shown), and / or more shaping optics (not shown). Those skilled in the art will understand that different implementations may require different arrangements of optical elements (such as the order in which components the light passes through) without changing the fundamental nature of the transmitter system.

[0050] FIG. 3 illustrates the functional relationships among the components of a power receiver 104, such as the receiver shown in FIG. 1. The illustrated receiver 104 includes a power converter 302 that includes a PV array 130 of PV cells 132. The power converter 302 converts the power beam 108 from the laser 106 into electricity (or, in some implementations, into another useful form of energy). The receiver 104 may also include optics 304 that can shape or modify the received beam before it reaches the PV array 130, for example, as described in International Application No. PCT / US20 / 34093. In many implementations, the PV array 130 includes a thermal management system 306. This system can include passive or active cooling and can be configured to send a signal back to the transmitter 102 (e.g., via the RX communication unit 138) if any portion of the PV array 130 exceeds safe temperature limits.

[0051] The power converter 302 may further be connected to a power management and distribution (PMAD) system 308. The PMAD system 308 may provide power to a user device 310, a power bus 312, and / or an energy storage device 314. The PMAD system 308 may be connected to a controller 316, which may monitor the PV array 130 via sensors 140, such as the voltage, current, and / or temperature of individual photovoltaic cells, cell clusters, or the entire array, the voltage and / or current of the PMAD, or individual loads. The controller 316 may also include maximum power point tracking (MPPT) for the PV array 130, or MPPT may be processed by the PMAD system 308. The PMAD system 308 may also include a DC / DC converter, for example, to provide power to the devices 310, 312, 314 with preferred voltage and current characteristics. The telemetry unit 318 may transmit any or all of the above data back to the transmitter, for use in controlling the light beam 108, for example, via the RX communication unit 138. In some implementations, the controller 316 may be in communication with a receiver user interface 320, which may allow a user of the power receiver to locally view and / or manage receiver operation.

[0052] 3 also shows a signal 208 (e.g., an optical signal) sent by the receiver 104 back to the transmitter 102, which may be transmitted along the same path as the power beam 108, as shown. In some implementations, for example, the signal 208 may include a safety signal used to ensure an uninterrupted path from the transmitter 102 to the receiver 104. In some implementations, this signal may be sent from a safety emitter 136. Further details of safety systems can be found, for example, in commonly owned U.S. Patent Nos. 10,580,921, 10,634,813, 10,816,694, and 11,105,954, U.S. Patent Application No. 16 / 079,073, and International Patent Application No. PCT / US20 / 34104. In some implementations, the signal 208 may include a tracking signal used to position the power beam 108 over the power converter 302, such as a signal sent from a tracking emitter 134. Although the signal 208 shown in the figure is an “active” signal, in other implementations the emitters 134, 136 may be replaced by fiducial marks (not shown) that are identified by the transmitter 102 or other suitable components in the power transmission system.

[0053] Any receiver components requiring power, such as, but not limited to, thermal management system 306, RX communication unit 138, PMAD system 308, controller 316, telemetry unit 318, and / or user interface 320, may be powered by power converter 302 (either directly or via PMAD 308) as needed. If components are powered by converter 302, the system may include a battery (either as part of energy storage 314 or as a separate component) to power these components during startup or at other times when converter 302 is not providing power. <Waffle board layout>

[0054] Referring to FIG. 4( a), a circuit board 402 (hereinafter, “waffle board”) has a plurality of openings 404 therein through which PV cells 406 can be seen. To avoid unnecessary clutter, not all of the depicted PV cells are labeled, and fewer PV cells than may be present in a typical array are depicted. A PV array such as that shown in FIG. 4 may have as few as four PV cells, as many as 100 PV cells, or as many as 400 or more PV cells. While the depicted array is square, an array need not have a square shape. As discussed below in connection with FIG. 17, an approximately octagonal arrangement of PV cells may be advantageous, or other layouts may be used equally well. Those skilled in the art will understand that the PV cell layout may be circular, elliptical, square, or any other shape, and that having a shape similar to the expected shape of an impinging laser beam may be advantageous in many implementations.

[0055] Figure 4(b) is a side view of the same components as Figure 4(a), and the two views may be collectively referred to herein as Figure 4. As most easily seen in Figure 4(b), PV cells 406 are mounted on a carrier 408. They are positioned relative to the waffle board 402 so that light 108 can pass through openings 404 to reach the PV cells 406. Circuitry (not shown) for connecting the PV cells 406 and collecting the power generated by the conversion of light 108 can be conveniently located in or under the carrier 408, or it can be located in or over a shaded area 410 included as part of the waffle board 402. As shown in Figure 4, the openings 404 in the waffle board 402 are slightly larger than the PV cells 406, so that some of the light 108 at the edge of the opening may strike the carrier 408 rather than the PV cells 406. In some implementations, this is an advantageous arrangement, but in other implementations, the apertures 404 can be smaller (or the PV cells 406 can be larger) so that substantially all of the light 108 is directed onto the PV cells 406. As shown, the carrier 408 is a single piece, but in other implementations, the PV cells 406 may be mounted on multiple carriers 408 (e.g., a separate carrier 408 for each PV cell 406, or multiple PV cells 406 on each of multiple carriers 408), which can be secured to a common substrate (not shown) or to each other.

[0056] In some implementations, a light concentrator may be attached to the waffle board 402. The use of light concentrators in conjunction with laser power beaming is more extensively discussed in co-pending, commonly owned patent application PCT / US20 / 34093, entitled "REMOTE POWER BEAM-SPLITTING," which is incorporated herein by reference to the extent not inconsistent herewith. FIG. 5 shows a side view of the waffle board 402, illustrating a concentrator reflector 512 positioned to direct light onto the PV cells 406. In other embodiments (not shown), lenses, other configurations of reflectors (e.g., curved reflectors), or other optical components may be used to direct light onto the PV cells 406. As shown in FIG. 5, the "dead space" 514 may be used for electronics, thermal management components, or other desired components of the receiver.

[0057] The waffle board 402 may include wiring for interconnecting the PV cells 406 with each other and / or with a powered load (not shown). In some implementations, the waffle board 402 may be a multi-layer circuit board, and wiring for different voltage levels (described further below) may be located on different levels of the multi-layer circuit board. In some implementations, all wiring that varies for a particular application may be located within the waffle board 402, such that an array of PV cells can be switched for a particular wiring scheme by swapping in the appropriate waffle board 402. The waffle board 402 (or other components of the system, such as the carrier 408) may also include dynamic wiring components, such that PV cell wiring can be programmatically switched instead of being hard-wired into the system. This concept is discussed further below in the section entitled "Dynamic Wiring."

[0058] Also shown in FIG. 5 is a heat sink 516. In some implementations, the heat sink 516 can be used as a mechanical reference for optical components when constructing a receiver. In such implementations, the heat sink 516 can be flat to within a selected tolerance for the receiver, and all other components (e.g., the waffle board 402, the PV cell 406, the carrier 408, the reflector 512) are positioned relative to the heat sink 516. Optical reference surfaces are well known for interferometers and the like, and they are typically flat to a fraction of the wavelength of light used, such as λ / 4 or λ / 20 (typically about 100 nm), across the width of the component. When the heat sink 516 is used as a mechanical reference, this flatness is typically not required, and the heat sink 516 can be flat to within 25 μm, 100 μm, or even 1 mm or more across the width of the heat sink 516. In these implementations, the heat sink 516 may be used not only as a reference for vertical alignment, but also for horizontal alignment of the PV cells 406, waffle board 402, carrier 408, carrier substrate (not shown), concentrator 512, or any other component of the system. FIG. 5 also shows mechanical supports 518 at the edges of the array, where the waffle board 402 is secured in a fixed position relative to the heat sink 516. It will be understood that these mechanical supports may be placed anywhere and at any convenient interval to hold the waffle board 402 in the correct position relative to the heat sink 516. An advantage of using the heat sink 516 as a reference is that it is often physically large and constructed of metal or other rigid material, although neither of these characteristics is required (or necessary) for it to be used in this manner.

[0059] Figure 6 is a schematic diagram of a receiver including a perforated heat sink. This configuration allows the PV cells to be separated from the electronics, allowing the heat sink to be placed closer to the PV cells for efficient cooling while leaving sufficient space for the electronics behind the heat sink. Another advantage of this configuration is that all of the PV cells are closer to the same temperature, potentially improving the efficiency of power conversion. The receiver includes an optical element 602, which is the first element to encounter the incident power beam. Such optical elements include, for example, lenses, mirrors, filters, windows, optical flats, prisms, polarizers, beam splitters, wave plates, optical fibers, and retroreflectors. The power beam passes through a chamber 604 to a PV cell 606, where it is converted to electricity, as described below. The PV cell 606 is mounted on a PV carrier 608, which in the illustrated implementation is a printed circuit board. In other implementations, carriers made of metal, plastic, or other suitable materials known in the art can be used. The PV carrier 608 is in thermal contact with the heat sink 610, for example, by being mounted on the heat sink or connected to the heat sink by a thermally conductive element. In some implementations, there may be no PV carrier 608, and the PV cells 606 may be mounted directly on the heat sink 610. Even when the PV cells 606 are on a PV carrier 608 that is in contact with the heat sink, the cells may still be described as "mounted on" the heat sink 610.

[0060] In the illustrated implementation, the heat sink 610 is a water block, but other implementations may use heat pipes, vapor chambers, solid metal components, solid composite materials such as encapsulated graphite, or other heat transfer structures known in the art. The water block 610 in FIG. 6 is connected to a water source by a cooling water connection 612. Water flows through portions of the block adjacent to the PV cells 606, carrying heat generated by the PV cells 606 away from the block. In other implementations, other cooling fluids can be used to transport heat, and other configurations of the heat sink 610 are also contemplated. For example, if the heat sink 610 is a vapor chamber or heat pipe, heat can be used to vaporize a cooling fluid that is transported away from the PV cells 606 and condensed for recirculation.

[0061] The heat sink 610 includes multiple openings 614 through which electrical connectors 616 pass. The electrical connectors 616 connect at one end to the output terminals of the PV cells 606 and at the other end to a PV interface board 620 via connectors 618 (shown as pins in the figure). Each PV interface board 620 can be connected to one or more PV cells 606. In some implementations, for example, PV cells with relatively low voltage / high current output (e.g., single-junction PV cells) can be connected using multiple electrical connectors 616, while in other implementations, PV cells with relatively high voltage / low current output (e.g., multi-junction PV cells) can be connected using fewer electrical connectors. The PV interface boards 620 can perform various electrical functions. For example, they can include electrical sensors, such as current or voltage sensors, that can be used to monitor current, voltage, and / or power from individual PV cells 606 or collections of PV cells 606. They may also include environmental sensors (e.g., measuring temperature or humidity), which may involve measuring environmental parameters directly at the PV connector board and / or accepting input from sensors located near the PV carrier 608 or elsewhere in the receiver. The sensor signals may be used locally to control operation and / or may be transmitted to the telemetry unit 318 for communication to the power beam transmitter 102, as described above. The PV interface board 620 may include a DC / DC converter or regulator, such as a voltage boost circuit and / or an MPPT circuit. In FIG. 6, they are further connected to a power output connector 622, which may be used to store energy in a battery and / or for direct connection to a load.

[0062] By placing the heat sink 610 near the PV cells 606 and routing the electrical connectors 616 through the heat sink 610 to electronics located further from the PV cells 606, the illustrated configuration allows heat generated by the PV cells 606 to be efficiently removed from the system while leaving sufficient space for the electronics. In some implementations, the electronics on the PV interface board 620 may also be cooled by the heat sink 610 (or by another heat sink), but the PV cells 606 may often be the most significant source of waste heat to be removed from the receiver. In some implementations, heat may also be generated by portions of the power beam that "miss" the collecting surfaces of the PV cells 606, and this heat may also be removed by the heat sink 610. Placing the heat sink 610 near the PV cells 606 may regulate their temperature to improve power generation.

[0063] In the illustrated implementation, the heat sink 610 serves as an indexing surface for the PV carrier 608 and the sidewalls of the chamber 604, which in turn determine the position of the PV cell 606 and the optical element 602. This indexing allows the optical element 602 to be precisely positioned relative to the PV cell 606, thereby placing the cell 606 in a desired location, such as near the focal point of a lens. This concept is further discussed in co-pending and commonly owned U.S. Provisional Patent Application No. 63 / 140,256.

[0064] FIG. 7 is a schematic diagram illustrating another implementation of a power receiver. FIG. 7a is a top view, and FIG. 7b is a bottom view. (For clarity, optics 602 and chamber 604 are omitted from the figure, but this implementation may still include optics if desired.) As shown, heat sink 710 is a vapor chamber placed in contact with PV carrier 608, as discussed above. Heat sink 710 may be connected to cooling fin assembly 724 by heat pipes 726. Cooling fin assembly 724 includes multiple fins that are cooled by forcing air over them using cooling fan 728. In some implementations, cooling fan 728 may not be needed, for example, if the receiver is used in a moving vehicle or if natural convection is sufficient. In some implementations, the heat sink 710 and heat pipe 726 may be replaced by a 3D vapor chamber having a substantially similar geometry but with a unified shared vapor space, which may result in lower thermal resistance between the PV carrier 608 and the cooling fin assembly 724. <Distributed wiring configuration>

[0065] Because each PV cell in a PV array generates a relatively small voltage compared to a typical load, PV arrays are typically wired to place several PV cells in series with each other, adding their voltages to produce a more usable output voltage. In some arrays, "strings" of PV cells are wired in series, and then the strings are wired in parallel, thereby adding the string output currents. In other arrays, as shown in FIG. 8, PV cells are wired in parallel, and then the parallel strings are wired in series, as described further below. As described in U.S. Provisional Patent Application No. 60 / 999,817 by Kare, entitled "Photovoltaic Array" (hereinafter "Kare"), the former type of array functions efficiently if all PV cells in a series-wired string generate equal currents. If one PV cell in a string does not generate output due to damage or shadowing, it is bypassed by a bypass diode, reducing the current of that string but only losing a total output power from the array that is slightly more than what a single PV cell would have generated. However, when the PV cells are illuminated with varying amounts of light, the current in the series string is limited by the least illuminated PV cell that is not reverse biased. Note that while this is generally not an issue for uniformly illuminated solar arrays, when the PV array is illuminated by a laser beam that may be spatially non-uniform or may move relative to the array, this effect can limit the efficiency of power generation.

[0066] Kare described a system that physically distributes parallel-wired PV cells across the array surface. Both the arrays shown herein, i.e., those derived from Kare, and the innovative arrays described below, have the electrical wiring diagram shown in FIG. 8, although it should be noted that the physical locations of the PV cells in each array vary from layout to layout. Kare discloses a randomly arranged array in which PV cells of each of four voltage levels are spread across the array surface, and a "staggered" array in which the PV cells are divided into strings and groups that can be divided across columns. FIG. 9(a) shows the random array, and FIG. 9(b) shows the staggered array (FIGS. 9(a) and 9(b) may be collectively referred to herein as FIG. 9). In these figures, Kare's shape code has been replaced with a letter representing the voltage level of each PV cell. Regarding FIG. 9(b), Kare describes a 4×9 array of rectangular PV cells in his FIG. 5, but this is instead shown as "doubled" in FIG. 9(b) to form an 8×9 array of square PV cells. Kare describes this repeating array in a paragraph spanning three or four pages. While the array shown in Kare uses rectangular PV cells with significant spacing between them, most of the new arrays described herein are shown with square PV cells with little or no spacing between them. Arrays of this latter type may use concentrators to capture substantially all of the incident light (as shown in FIG. 5), or may simply be placed very closely together so that minimal light gets between the PV cells.

[0067] The array of Figure 9, as well as a pre-Kare array of parallel-wired strings of PV cells, with PV cells wired in series within each string, will be compared to the new array in the following discussion. Kare does not describe how to generalize his array to larger sizes (other than by iteration as described above), nor does he describe rules for creating additional PV array layouts beyond the two examples. We provide the following principles for creating new PV array layouts with superior performance.

[0068] There are many external factors that influence the number of voltage levels for a PV array design that uses parallel wiring for groups of PV cells. In particular, there may be a desired total output voltage for the design load, or minimum or maximum voltage limits that the load can handle. The nominal output voltage of the PV cells divided by that desired output voltage typically guides the number of voltage levels, but other factors to consider include the desired size of the PV array, the desired number of PV cells in the array, how a particular number of voltage levels can be evenly divided among the quantity of PV cells, and the provision of optional DC voltage converters and regulators (discussed further below). While Kare's array was shown with four voltage levels, the inventors have found that, at least in some cases, five or six levels may allow for the avoidance of the need to install voltage converters, thereby saving space and weight for the PV array. In some implementations, the power receiver may be incorporated into a mobile component that can be driven or flown from one location to another; therefore, weight may be a very important consideration in receiver design for such implementations. Even more voltage levels may be preferred in certain implementations: we envision arrays with as many as 75 voltage levels with 4-10 (or more) PV cells per level, but we expect that for most applications, 6-30 voltage levels will be sufficient, and that as few as 4-6 voltage levels will be suitable in many cases.

[0069] Generally speaking, the inventors have found that arrays that perform best when exposed to beam wander and beam intensity profile variations have PV cells at any one level spatially "uniformly" distributed across the PV array (or arrays that perform best when exposed to beam wander and beam intensity profile variations have PV cells at any one level spatially "uniformly" distributed across the PV array). The metric used to determine this distribution uniformity is to generate a Voronoi mesh using the centers of the PV cells at each voltage level and then examine the aspect ratio of the Voronoi cells in the mesh. The inventors have found that the best performing arrays have Voronoi cell aspect ratios that are practically close to 1.0, and preferably have a median aspect ratio of less than 1.5, more preferably less than 1.3, or even more preferably less than about 1.1. Figure 10 shows the Voronoi mesh of the Kare array shown in Figure 9(b), along with a histogram of Voronoi cell aspect ratios. The histogram shows Voronoi cell aspect ratios ranging from 1.3 to 2.2, with the median-shaped Voronoi cell having an aspect ratio of 1.5. For comparison, the mesh of the new array discussed below in connection with Figure 22 is shown in Figure 11, with its accompanying histogram in Figure 12 showing Voronoi cell aspect ratios ranging from 1.0 to 2.6, with the median-shaped Voronoi cell having an aspect ratio of 1.31. Note that the Voronoi cells with the highest aspect ratios often appear at the edges of the array.

[0070] In some implementations of the array design process of the present invention, the pattern of voltage levels may be "extended" beyond the edges of the physical array for purposes of Voronoi cell calculation. For example, instead of an 8×8 array as shown in FIG. 9(b), the same regular pattern is used to determine the Voronoi cells of a 12×12 array, and then only the aspect ratios of the cells corresponding to the members of the central 8×8 array are determined, resulting in the modified Voronoi diagram and corresponding aspect ratio histogram shown in FIG. 13. A similar extension of the array shown in FIG. 11 leads to the Voronoi diagram and corresponding aspect ratio histogram shown in FIG. 14. This extension can avoid artifacts at the edges of the array, where cells appear to have larger aspect ratios; in each of FIGS. 13 and 14, all of the Voronoi cells have the same aspect ratio. However, even with these expanded views, the array shown in FIG. 14 has cells with lower aspect ratios than those shown in FIG. 13.

[0071] To achieve an array layout with evenly spread PV cells at each voltage level, one method we have used is to create a “staggered” array in which the same PV cells are offset horizontally or vertically from each other so that they are not adjacent to each other, creating a repeating pattern of PV cell voltage levels in each column. (The Kare array shown in FIG. 9(b) is described as “staggered,” but does not have a consistent offset from column to column. As used herein, “staggered” means an array with a consistent offset from column to column unless the context clearly dictates otherwise.) As used herein, “adjacent” means having adjacent edges, and “diagonally adjacent” means having adjacent corners, such as the two A-level cells in the upper left corner of FIG. 9(a). When two PV cells are described as “non-adjacent,” they can still be diagonally adjacent unless further restrictions are added. One staggered array 1500 is shown in FIG. 15. The PV cells 1502 are arranged in a 10x10 array and labeled to indicate which of the five voltage levels they belong to. As shown, the PV cells in successive columns are staggered with an offset of 2, i.e., horizontally adjacent PV cells are at level -2 to the right of the column and +2 to the left (modulo 5), which creates an array configuration in which no two PV cells 1502 are adjacent or diagonally adjacent. The contour lines shown in Figure 15 are described below in connection with Figures 23 and 24. Figure 16 shows the Voronoi cells for the current level A and also shows a histogram of the aspect ratios of the Voronoi cells in Figure 16. The median aspect ratio of the aspect ratios of the Voronoi cells in this array is 1.33 (as shown in Table 1). Those skilled in the art will understand that many possible combinations of array size, number of voltage levels, and offsets can be selected. To produce a Voronoi cell with a low aspect ratio, it is believed that the offset should be greater than 1 and at least 2 less than the number of voltage levels.Also, although it is believed that the number of offsets and voltage levels should have a greatest common denominator (GCD) of 1 (or the greatest common denominator should be 1), some layouts with larger GCDs may also produce Voronoi cells with sufficiently low aspect ratios.

[0072] Another array 1700 is shown in Figure 17. This array is also based on the 10x10 array like Figure 15, but the corner PV cells have been removed from the array. This shape has been found to be advantageous for use with beams that have approximately circular symmetry. Note that the symmetrical removal of the corners can change the number of PV cells in each voltage group so that they are no longer equal. While it may be possible or even advantageous in some implementations to build a PV array with a different number of PV cells at each voltage level, it has generally been found advantageous to maintain the same number of PV cells at each level, if possible. A "perfect" arrangement of PV cells in a 10x10 array with six PV cells removed at each corner would leave 76 PV cells, which cannot be evenly divided among the five voltage levels. For this reason, one PV cell that would otherwise be on level B has been omitted at one edge of the array, seen in the lower right of Figure 17. PV cells at the array edge are generally expected to contribute less to the total delivered power, since the beam often (but not always) has a higher intensity at the center than at the edge.

[0073] The array shown in FIG. 17 is theoretically modeled as discussed below, but has also been physically constructed and used for FSP power beaming. As described in connection with FIGS. 4 and 5 above, the physical array includes a multi-layer circuit board, a waffle board 402, with connections for PV cells 406 of different voltage levels separated onto different layers of the circuit board. Individual PV cells 406 are connected only to a carrier 408, which also contains a thermistor for monitoring PV cell temperature, and are not directly connected to other PV cells. All connections between PV cells (as well as the temperature monitoring signal from the thermistor, not shown) are located within the waffle board 402. In this type of embodiment, new PV cell layouts such as those discussed herein can be easily and quickly implemented by designing and fabricating a new waffle board 402 without changing any other components.

[0074] We compared our array model, generated as described above, with the Kare array model to examine their respective qualities. While the current output from a PV cell is a function of the PV cell's IV curve at a given illumination intensity and temperature and is not a single fixed value, for modeling and comparison purposes we assume that the PV cells are operating near their maximum power point and that illumination intensity can be directly and approximately linearly converted to output current. For each voltage level in the array, we define a "level current" that is the sum of the currents from all PV cells at that voltage level. Arrays generally perform best when the level currents at each voltage level are approximately equal, so that each PV cell in a single series string should be equally illuminated to match the current. In other words, the difference between the level currents is preferably minimized. Ideally, a PV array is designed so that the minimized difference between the level currents is robust to power beam intensity profile variations or beam centroid wander, i.e., when the beam wanders slightly or its profile changes, the change in the difference between the level currents is minimized. Using the above assumption that the current from a PV cell is approximately linearly proportional to the input power, our model uses the incident light on the PV cell as a proxy for the PV cell current to estimate the nominal current from each PV cell. The following description may use the terms "intensity," "power," "power intensity," "current," or "current density" interchangeably, as they are all assumed to be proportional to each other in our model.

[0075] To characterize our test arrays, we define "mismatch" as the difference between the maximum and minimum currents divided by the average current, expressed as a percentage. Because the total power over the focused area of ​​a PV cell is substantially equivalent to the power at its center for a nonpathological beam intensity profile, we use the light intensity at the center of the PV cell as a proxy for its output current. While a more complete model could use the intensity integrated over the area of ​​the PV cell, we modeled this difference and found it to provide only a marginal improvement; therefore, we use the intensity at the PV cell center to simplify the calculations. We then generate a "virtual" light beam profile with parameters describing its width in the major and minor axes, its rotation angle relative to the PV array, the amount by which it approximates a rectangle or ellipse, and the intensity profile (typically modeled as a super-Gaussian shape, with the super-Gaussian coefficients as one of the parameters). We use Monte Carlo techniques to simulate the translation and / or rotation of the beam and / or the modification of its profile. Figure 18 shows an example beam profile designed to roughly approximate the shape and size of the Kare array shown in Figure 9(a). The applied beam profile is elongated to match the aspect ratio of this 4x8 array, as shown in the figure.

[0076] Our centered virtual light beam profile can be described by six input parameters as follows: x and w y represents the beam width in the x and y directions, θ represents the rotation of the beam in the xy plane, and n x , n y , and n sG represents the super-Gaussian parameter of the beam profile. x and n yare applied separately to the x and y components, and the larger these two parameters are, the more rectangular the beam profile becomes than elliptical, and n sG is a regular super-Gaussian coefficient, the larger it is, the closer the beam profile is to a "top-hat" profile instead of a regular Gaussian. The beam intensity at a given position is then described by the following parameters:

[0077] a, b, and c are defined as follows: TIFF2026016446000003.tif41169

[0078] The intensity J at point x, y is written as follows: TIFF2026016446000004.tif10169

[0079] To compare relative array performance primarily to mismatch, absolute intensity is irrelevant; therefore, for ease of modeling, the peak intensity J0 is simply set to 1. Our Monte Carlo simulations allow the beam to wander in the x and y directions, selecting positions with applied errors having a normal distribution with selected standard deviations (shown in Table 1 as "Beam Wander," expressed as a fraction of the PV cell width) that can be expected to naturally occur due to various sources of "noise" for the beam steering system (from tracking, signal processing, mechanical motion, etc.). Note that random position errors are generated (with a normal distribution) separately into x and y position errors. The above equation is shifted in the x and y planes to determine the intensity at the center of each PV cell position. Two hundred Monte Carlo runs were performed for each of the various cases discussed below. Table 1 lists the array parameters, beam profile, and Monte Carlo input coefficients for each case described below, along with associated performance results. TIFF2026016446000005.tif100169

[0080] The Kare array shown in FIG. 9(a), modeled as described above, performs relatively poorly, exhibiting a 22.1% mismatch relative to the beam profile shown in FIG. 18. The beam profiles in FIG. 18 and other figures exhibit constant intensity contours ranging from 0.1 to 0.9 (the peak at 1.0 may be a single point in the center of the beam; the low intensities below 0.1 off the tail of the profile are not important for this application, as they exhibit contours below 0.1). FIG. 19 shows the stacked current for each of the four voltage levels when the beam in FIG. 18 is centered at the array. Each white bar in FIG. 19 represents the current from a single PV cell, which are added together to form the total output current, represented by the height of the stacked bar in each column of these parallel-wired PV cells. The mismatch (shown in Table 1) is evident by examining the graph in FIG. 19, indicating that the array shown in FIG. 9(a) is substantially inferior to the arrays described further below. Ideally, each of these total currents shown in FIG. 19 would be the same, rather than stacked at different heights as shown.

[0081] When modeling the array shown in Kare's Figure 5, for a closer comparison with our arrays, which typically have an overall aspect ratio close to 1, we "doubled" the array (as shown in the paragraph spanning pages 3-4 of Kare's work) by placing two identical arrays side-by-side to create a 9 x 8 array of PV cells (instead of Kare's 9 x 4 array), as shown in Figure 9(b), and used a slightly eccentric beam profile to match the array's slightly non-square shape. The beam shape and size were defined as above, with the parameters listed in Table 1, and the x and y positions were varied in the Monte Carlo simulations as described above with the standard deviations listed in Table 1. One profile from the simulation is shown in Figure 20: the size and eccentric chape (or eccentric shape) of the beam profile can be seen in the contour lines. This shape reflects the beam profile that might result when a beam designer attempts to create a rectangular beam to match the array shape (Kare denotes a substantially rectangular beam), and the stacked currents for each of the four voltage levels for the illustrated profile are shown in Figure 21. The mismatch for this test configuration is smaller than that for the other Kare arrays, but is still relatively high: 5.6% for the illustrated run and 6.2% average across all runs of the Monte Carlo simulation.

[0082] To best compare the performance of the array shown in Figure 21, we created an 8x8 array with four voltage levels constructed using the design principles described above, as shown in Figure 11. Because it is more common to have beams with an aspect ratio of 1, and therefore receivers with the same width and height, we used an 8x8 array (instead of a 9x8 array like Kare's) to maintain a constant offset of 2 while still having the same number of PV cells at each voltage level. Figure 22 shows the stacked currents for a beam centered on the array as shown in Figure 11. For the same beam profile shown in Figure 20, the mismatch was zero. The mismatch averaged across all simulation runs of this array was 1.7%, indicating significantly better performance than Kare's array.

[0083] In comparison, Figures 23 and 24 show the same stacked current graphs for the center beam cases of the arrays shown in Figures 15 and 17, respectively (i.e., a 10x10 array with five voltage levels and the same array with some PV cells near the corners removed). Similar to Figure 11, Figure 15 shows the substantially circular beam profile used in modeling the response of these two arrays. Monte Carlo simulations performed on these two arrays yielded average mismatches of 1.1% and 2.7%, respectively, indicating that the array layouts are expected to perform better than those described in Kare. A review of Table 1 reveals that, as expected, a lower Voronoi cell median aspect ratio correlates with a lower beam mismatch. <Voltage boost>

[0084] In some cases, the nominal output voltage of a PV cell requires an excessively large number to be connected in series to reach the desired array output voltage. In other cases, the current from a PV cell may become so high that ohmic losses become unacceptably large (or the size of the wiring required to extract the current becomes unacceptably large). In these cases, one or more PV cells of the same voltage level can have a DC / DC voltage boost circuit connected to the PV output, thereby increasing the voltage seen by the rest of the array and reducing the current that needs to be carried across the wiring.

[0085] There are various DC / DC boost circuit topologies, and their performance varies depending on requirements. Some regulate the input to a fixed, narrow voltage output, even if the input varies over a relatively wide voltage range. Another option is a variable boost with a fixed input voltage setpoint (e.g., set to the maximum peak power voltage of the PV cell), which adjusts the boost ratio to achieve that MPP. In this case, the output voltage "floats," or is not regulated; instead, the load (e.g., a battery) controls the output voltage by sinking current. An MPP with a dynamic input setpoint is MPPT (maximum power point tracking), in which an algorithm dynamically adjusts the boost ratio to maintain the PV device at peak power, for example, by measuring both current and power to calculate the power. This peak power tracking can be based on the power from the PV device or the power from the converter. Another boost circuit option is the so-called "fixed ratio" circuit, which increases the input voltage by a fixed multiplication ratio. Boost (and buck) DC / DC voltage converters are well known to those skilled in the art and will not be further described here. Details can be found in electronic texts such as Pressman et. al, Switching Power Supply Design, 3d ed., McGraw Hill, 2009, pp. 31-43, which is incorporated herein by reference to the extent not inconsistent herewith.

[0086] While any of the above types of boost circuits can be used with the distributed wiring configurations described herein, the use of fixed-ratio boost converters is particularly attractive for efficiently balancing PV cell and PV cell group output currents while achieving a desired output voltage. In particular, when using a fixed-ratio type boost circuit, the boosted output is expected to behave like a non-boosted PV cell (e.g., exhibit a similar IV curve shape) rather than like a fixed-voltage device. Such use of a DC boost circuit can allow the rest of the array electronics to be "agnostic" with respect to PV cell materials, single-junction versus multi-junction, or other characteristics of the PV cells. In one specific example, a multi-junction InGaAs PV cell has a nominal output voltage of ∼5 V, and a single-junction InGaAs PV cell has a nominal output voltage of ∼0.7 V (both of these types of cells are designed for 976 nm light, but those skilled in the art will understand that the same principles apply to other wavelengths). A fixed ratio boost of approximately 7 times (7×) allows a 0.7V PV cell to behave like a 5V cell as far as the rest of the array and connected electronics (e.g., PMAD hardware 308) are concerned. If voltage boost electronics providing a 7× boost are installed on a carrier 608 for a single-junction cell, it can be swapped for a carrier 608 carrying a multi-junction cell (without voltage boost) without modifying any other hardware. Of course, other combinations of light wavelengths, PV cell materials, and boost circuitry are possible. This type of interoperability can have advantages for receiver design and manufacturing. <Dynamic Wiring>

[0087] As mentioned above, in some implementations, the waffle board 402 (or other similar components, such as the PV carrier 608) may allow programmable switching of the wiring of the PV cells 406, allowing series and parallel connections to be adjusted to suit PV cell selection, power beam parameters, environmental operating conditions, or to achieve other engineering goals that will occur to those skilled in the art. For example, it may be desirable to use different numbers of voltage groups depending on the size and / or profile of the input power beam. In another example, when the array is initially deployed, the wiring is switched to a particular layout only once, allowing the same array switching hardware to be used for multiple different power beaming installations with different required output voltages.

[0088] In some implementations, the receiver 104 may include a processor configured to determine the optimal series-parallel layout for the incident beam (and, in some implementations, the output load requirements) and establish that wiring layout at the start of power beaming. With a sufficiently fast and versatile processor, the receiver 104 may even be able to switch to the optimal layout “on the fly.” However, if it is undesirable to provide too much processing power for this task (e.g., if the processor consumes more power than the savings achieved by using the optimal layout), it may be preferable to provide a small (or large) “library” of PV cell wiring layouts to select from a list rather than having the receiver 104 determine the layout ab initio. Such a selection may be performed automatically by the receiver 104 or may be selected manually, for example, using the user interface 320.

[0089] In one example, the processor contains a library of three PV cell wiring layouts for a 10×10 array of cells, and the receiver 104 contains the appropriate physical wiring to implement any of the three by the operation of switches or equivalent components. A first layout (which may be used as a default layout) includes five voltage groups arranged as shown in FIG. 15. A second layout may include ten voltage groups, arranged in a staggered pattern with an offset of three. A third layout may use only the central 8×8 set of PV cells, grouping them into four voltage groups and arranging them in a staggered pattern with an offset of two, as shown in FIG. 11. During use of this exemplary receiver, the processor may determine (or the user may select) that a higher output voltage is needed and respond by switching the wiring from the default first layout to the second layout. Alternatively, the processor may determine (e.g., by communicating with sensors that detect the output current at individual PV cells) that the incident power beam is tightly focused enough that the outermost PV cells only contribute very little to the output current, and respond by switching to the third layout. Although these examples describe switching between different PV cell layouts on a relatively long time scale, in some implementations this type of switching can occur rapidly and continuously, for example, in response to scintillation of the power beam.

[0090] In some implementations, a dynamic wiring configuration may be used to implement DC / DC voltage boost. DC / DC converters require power to operate, so in some implementations where multiple converters are provided, it may be useful for a processor to monitor the current and choose to shut down some converters if they are not saving more power than they are using. In extreme cases, the receiver 104 may include boost circuitry for each PV cell, while the entire PV array may power one DC / DC converter when the luminous flux is at a minimum. Of course, intermediate cases are also possible.

[0091] Further features, characteristics and advantages are described below for each item:

[0092] Item 1: A power receiver includes a plurality of photovoltaic (PV) cells arranged on a support surface and electrical wiring for interconnecting the PV cells. The PV cells are divided into a plurality of voltage groups, each having a selected output voltage and output current. The wiring is configured to connect each PV cell in a voltage group in parallel and to connect each voltage group in series to at least one other voltage group. The PV cells in each voltage group are arranged discontinuously with each other on the support surface, and the plurality of voltage groups exhibit a current mismatch of less than 5% when the receiver is exposed to a power beam, where the current mismatch is defined as the difference between the maximum and minimum output currents divided by the average output current. This type of power receiver may provide the technical advantage of improving power conversion efficiency by reducing current mismatch.

[0093] Item 2: The power receiver of item 1, wherein the power beam is a laser power beam.

[0094] Item 3: The power receiver of item 1 or 2, wherein the power beam has a substantially Gaussian beam profile.

[0095] Item 4: The power receiver according to any one of Items 1 to 3, wherein the power beam has a super-Gaussian beam profile.

[0096] Item 5: The power receiver according to any one of items 1 to 4, wherein the current mismatch is less than 4%.

[0097] Item 6: The power receiver according to any one of items 1 to 5, wherein the current mismatch is less than 3%.

[0098] Item 7: The power receiver according to any one of items 1 to 6, wherein the current mismatch is less than 2%.

[0099] Item 8: The power receiver according to any one of items 1 to 7, wherein the current mismatch is less than 1%.

[0100] Item 9: The power receiver according to any one of items 1 to 8, wherein the PV cells are arranged in a rectangular shape.

[0101] Item 10: The power receiver according to any one of Items 1 to 9, wherein the PV cells are arranged in a square.

[0102] Item 11: The power receiver according to any one of items 1 to 10, wherein the PV cells are arranged in a square with corners truncated.

[0103] Item 12: The power receiver according to any one of items 1 to 11, wherein the PV array includes four voltage groups.

[0104] Item 13: The power receiver of any one of items 1 to 12, wherein the PV array includes five voltage groups.

[0105] Item 14: The power receiver of any one of items 1 to 13, wherein the PV array includes six voltage groups.

[0106] Item 15: A power receiver includes a plurality of photovoltaic (PV) cells arranged on a support surface and electrical wiring for interconnecting the PV cells. The PV cells are divided into a plurality of voltage groups, each voltage group having a selected output voltage and output current. The wiring is configured to connect each PV cell in a voltage group in parallel and to connect each voltage group in series to at least one other voltage group. The PV cells in each voltage group are arranged in a repeating pattern along a first axis of the PV array, and the repeating pattern is staggered by an offset value along a second axis of the PV array. The offset value is selected so that PV cells in the same voltage group are not adjacent to each other. This type of power receiver may provide the technical advantage of improving power conversion efficiency by reducing current mismatch.

[0107] Item 16: The power receiver according to item 15, wherein the PV cells are connected in series with one or more adjacent PV cells along the first axis, and the PV cells belonging to each voltage group are connected in parallel by additional wiring.

[0108] Item 17: The power receiver according to item 15 or 16, wherein additional wiring is disposed within the support surface.

[0109] Item 18: The power receiver according to any one of items 15 to 17, wherein additional wiring is located behind the support surface.

[0110] Item 19: A power receiver according to any one of items 15 to 18, wherein additional wiring is disposed within a circuit board having openings arranged to allow light to pass through and reach the PV cells.

[0111] Item 20: The power receiver according to any one of Items 15 to 19, wherein the PV cells are arranged to form a rectangle.

[0112] Item 21: The power receiver according to any one of Items 15 to 20, wherein the PV cells are arranged to form a square.

[0113] Item 22: The power receiver according to any one of Items 15 to 21, wherein the PV cells are arranged to form a square with the corners truncated.

[0114] Item 23: The power receiver according to any one of items 15 to 22, wherein the PV array includes four voltage groups.

[0115] Item 24: The power receiver according to any one of Items 15 to 23, wherein the PV array includes five voltage groups.

[0116] Item 25: The power receiver according to any one of items 15 to 24, wherein the PV array includes six voltage groups.

[0117] Item 26: A power receiver includes a plurality of photovoltaic (PV) cells arranged on a support surface and electrical wiring for interconnecting the PV cells. The PV cells are divided into a plurality of voltage groups, each having a selected output voltage and output current. The wiring is configured to connect each PV cell in a voltage group in parallel and to connect each voltage group in series to at least one other voltage group. Each voltage group has the characteristic that a Voronoi mesh generated from the positions of the PV cells in the voltage group has a median Voronoi cell aspect ratio of less than 1.4. This type of power receiver can provide the technical benefit of improving power conversion efficiency by reducing current mismatch by ensuring that PV cells of different voltage levels are evenly distributed across the array surface.

[0118] Item 27: The power receiver of item 26, wherein each voltage group has the property that a Voronoi mesh generated from the positions of the PV cells in the voltage group has a median Voronoi cell aspect ratio of less than 1.3.

[0119] Item 28: A power receiver including a plurality of photovoltaic (PV) cells, a circuit board having a plurality of openings therein, and an output connector. Each PV cell has an active surface configured to receive light for conversion to electrical power, and a cathode connector and an anode connector configured to generate a voltage therebetween when the active surface of the PV cell is exposed to light. The circuit board is connected to at least one of the cathode connector and the anode connector, and the output connector is configured to electrically connect the circuit board to a load. Each PV cell of the plurality is positioned to receive light that has passed through at least one of the plurality of openings in the circuit board. This type of power receiver can provide the technical benefit of efficient use of space, allowing electronic devices to collect and convert more light into energy in a given area.

[0120] Item 29: The power receiver of item 28, further comprising a reflector associated with at least one PV cell of the plurality, the reflector configured to reflect light onto the active surface of the at least one associated PV cell.

[0121] Item 30: The power receiver of item 28 or 29, further including a plurality of reflectors, each reflector associated with at least one PV cell of the plurality, and each reflector configured to reflect light onto an active surface of the at least one associated PV cell.

[0122] Item 31: The power receiver according to any one of Items 28 to 30, wherein at least some members of the plurality of reflectors are disposed within openings in the circuit board.

[0123] Item 32: The power receiver of any one of Items 28 to 31, wherein the circuit board includes wiring configured to connect the first subset of PV cells in parallel.

[0124] Item 33: The power receiver according to any one of Items 28 to 32, wherein the wiring configured to connect the first subset of PV cells in parallel is disposed on a first layer of the circuit board.

[0125] Item 34: The power receiver of any one of Items 28 to 33, wherein the circuit board includes wiring configured to connect a second subset of the PV cells in parallel, and the second subset and the first subset do not have any PV cells in common.

[0126] Item 35: The power receiver of any one of items 28 to 34, wherein wiring configured to connect a first subset of the PV cells in parallel is disposed on a first layer of the circuit board, and wiring configured to connect a second subset of the PV cells in parallel is disposed on a second layer of the circuit board different from the first layer.

[0127] Item 36: The power receiver of any one of Items 28 to 35, wherein the circuit board further includes wiring configured to connect the first subset to the second subset in series, thereby generating a voltage approximately equal to the sum of a first voltage between the cathode connectors and anode connectors of the PV cells of the first subset and a second voltage between the cathode connectors and anode connectors of the PV cells of the second subset.

[0128] Item 37: The power receiver of any one of Items 28 to 36, wherein all electrical connections between different PV cells of the plurality include wiring within the circuit board.

[0129] Item 38: The power receiver of any one of Items 28 to 37, wherein the circuit board is configured to dynamically change connections between different PV cells.

[0130] Item 39: The power receiver of any one of Items 28 to 38, further including a heat sink configured to remove waste heat from the PV cell.

[0131] Item 40: The power receiver according to any one of Items 28 to 39, wherein the heat sink has a surface that functions as a reference surface for positioning an optical component of the power receiver.

[0132] Item 41: A power receiver includes a heat sink including a first side, a second side, and an opening passing from the first side to the second side, a current collecting device in thermal contact with the first side of the heat sink, an electronic component disposed on the second side of the heat sink, and an electrical connector disposed within the opening in the heat sink. The electrical connector connects the current collecting device to the electronic component. This type of power receiver may provide the technical advantage of allowing more space for the electronics and allowing more light to be collected and converted to energy in a given area without blocking light or requiring additional space between cells. Further technical benefits may be achieved by locating (or thermally connecting to) the heat sink closer to where waste heat is generated, allowing the current collecting devices to operate at temperatures closer to their preferred temperature, even in the presence of a high-energy power beam.

[0133] Item 42: The power receiver of item 41, wherein the heat sink is made from a thermally conductive material.

[0134] Item 43: A power receiver according to Item 41 or 42, wherein the thermally conductive material is a metal or a ceramic.

[0135] Item 44: The power receiver according to any one of Items 41 to 43, wherein the current collecting device is a photovoltaic (PV) cell.

[0136] Item 45: A power receiver according to any one of items 41 to 44, wherein the heat sink includes an internal channel configured for circulation of a cooling fluid.

[0137] Item 46: The power receiver of any one of Items 41 to 45, wherein the heat sink includes a vapor chamber.

[0138] Item 47: A power receiver described in any one of items 41 to 46, wherein the heat sink includes a plurality of openings passing from the first side to the second side, and the power receiver further includes a plurality of electrical connectors arranged with the openings in the heat sink.

[0139] Item 48: A power receiver described in any one of Items 41 to 47, further including a plurality of current collecting devices attached to the first side of the heat sink, and the plurality of electrical connectors connecting each one of the plurality of current collecting devices to the electronic component attached to the second side of the heat sink.

[0140] While the above has set forth what is considered to be the best mode and / or other examples, it should be understood that various modifications can be made herein, that the subject matter disclosed herein can be implemented in various forms and examples, and that the teachings can be applied to numerous applications, only a few of which have been described herein. It is intended that the following claims claim any and all applications, modifications, and variations that fall within the true scope of the present teachings.

[0141] Unless otherwise specified, all measurements, values, estimates, positions, dimensions, sizes, and other specifications set forth in this specification, including the following claims, are approximate rather than exact and are intended to have a reasonable range consistent with the function to which they relate and that which is customary in the technical field to which they pertain.

[0142] The scope of protection is limited only by the claims that follow. That scope is intended to be as broad as possible, consistent with the ordinary meaning of the language used in the claims when interpreted in light of this specification and the following prosecution history, to encompass all structural and functional equivalents. Nevertheless, no inclusion of subject matter that does not meet the requirements of 35 U.S.C. §§ 101, 102, or 103 is intended, and should not be so construed. Any unintended inclusion of such subject matter is hereby disclaimed.

[0143] Except as set forth in the preceding paragraph, nothing described or shown, whether claimed or not, is intended to or should be construed to cause appropriation of any element, step, feature, object, benefit, advantage, or equivalent to the public.

[0144] It will be understood that the terms and expressions used herein have the ordinary meanings ascribed to such terms and expressions with respect to their corresponding respective fields of inquiry and research, unless a specific meaning is otherwise stated herein. Relative terms such as first and second may be used only to distinguish one entity from another, without necessarily implying any relationship or order between such entities. The terms "comprise" and "include," in all their grammatical forms, are intended to cover non-exclusive inclusions; thus, a process, method, article, device, or composition that includes or includes a list of elements may also include other elements not expressly listed. An element preceded by "a" or "An" does not, without further constraints, exclude the existence of additional identical or similar elements.

[0145] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It should be understood that the Abstract is not used to interpret or limit the scope of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features may be grouped together in various examples for clarity of explanation. This method of disclosure should not be interpreted as reflecting an intention that the claims require more features than are expressly recited in each claim. Furthermore, features from one example may be freely included in another, or substituted for one another, without departing from the overall scope and spirit of the present application. The following is the invention as originally described in the present application. <Claim 1> a plurality of photovoltaic (PV) cells disposed on a support surface, the PV cells being divided into a plurality of voltage groups, each voltage group having a selected output voltage and output current; Electrical wiring for interconnecting the PV cells, the wiring comprising: Each PV cell in a voltage group is connected in parallel, and the electrical wiring configured to connect each voltage group in series with at least one other voltage group, the PV cells of each voltage group are arranged discontinuously on the support surface; the plurality of voltage groups exhibiting a current mismatch of less than 5%; A power receiver, wherein current mismatch is defined as the difference between the maximum and minimum output current divided by the average output current when said receiver is exposed to a power beam. <Claim 2> The power receiver of claim 1 , wherein the power beam is a laser power beam. <Claim 3> 10. The power receiver of claim 1, wherein the power beam has a substantially Gaussian beam profile. <Claim 4> 10. The power receiver of claim 1, wherein the power beam has a super-Gaussian beam profile. <Claim 5> 10. The power receiver of claim 1, wherein the current mismatch is less than 4%. <Claim 6> 10. The power receiver of claim 1, wherein the current mismatch is less than 3%. <Claim 7> 10. The power receiver of claim 1, wherein the current mismatch is less than 2%. <Claim 8> 10. The power receiver of claim 1, wherein the current mismatch is less than 1%. <Claim 9> The power receiver of claim 1 , wherein the PV cells are arranged in a rectangular shape. <Claim 10> The power receiver of claim 1 , wherein the PV cells are arranged in a square. <Claim 11> The power receiver of claim 1 , wherein the PV cells are arranged in a square with corners truncated. <Claim 12> The power receiver of claim 1 , wherein the PV array includes four voltage groups. <Claim 13> The power receiver of claim 1 , wherein the PV array includes five voltage groups. <Claim 14> The power receiver of claim 1 , wherein the PV array includes six voltage groups. <Claim 15> a plurality of photovoltaic (PV) cells arranged on a support surface to form a PV array, the PV cells being divided into a plurality of voltage groups; Electrical wiring for interconnecting the PV cells, the wiring comprising: Each PV cell in a voltage group is connected in parallel, and the electrical wiring configured to connect each voltage group in series with at least one other voltage group, the PV cells of each voltage group are arranged in a repeating pattern along a first axis of the PV array, and the repeating pattern is staggered along a second axis of the PV array by an offset value, the offset value being selected so that PV cells within the same voltage group are not adjacent to each other. <Claim 16> 16. The power receiver of claim 15, wherein the PV cells are connected in series with one or more adjacent PV cells along the first axis, and the PV cells belonging to each voltage group are connected in parallel by additional wiring. <Claim 17> The power receiver of claim 16 , wherein the additional wiring is disposed within the support surface. <Claim 18> 17. The power receiver of claim 16, wherein the additional wiring is disposed behind the support surface. <Claim 19> 17. The power receiver of claim 16, wherein the additional wiring is disposed in a circuit board having openings positioned to allow light to pass through and reach the PV cells. <Claim 20> 16. The power receiver of claim 15, wherein the PV cells are arranged to form a rectangle. <Claim 21> 16. The power receiver of claim 15, wherein the PV cells are arranged to form a square. <Claim 22> 16. The power receiver of claim 15, wherein the PV cells are arranged to form a square with truncated corners. <Claim 23> The power receiver of claim 15 , wherein the PV array includes four voltage groups. <Claim 24> The power receiver of claim 15 , wherein the PV array includes five voltage groups. <Claim 25> 16. The power receiver of claim 15, wherein the PV array includes 6 to 16 voltage groups. <Claim 26> a plurality of photovoltaic (PV) cells arranged on a support surface to form a PV array, the PV cells being divided into a plurality of voltage groups; Electrical wiring for interconnecting the PV cells, the wiring comprising: Each PV cell in a voltage group is connected in parallel, and the electrical wiring configured to connect each voltage group in series with at least one other voltage group, A power receiver, wherein each voltage group has the property that a Voronoi mesh generated from the locations of PV cells in said voltage group has a median Voronoi cell aspect ratio of less than 1.4. <Claim 27> 27. The power receiver of claim 26, wherein each voltage group has the property that a Voronoi mesh generated from the locations of PV cells in the voltage group has a median Voronoi cell aspect ratio of less than 1.3. <Claim 28> A plurality of photovoltaic (PV) cells, each PV cell comprising: an active surface configured to receive light for conversion to electrical power; the plurality of photovoltaic cells having a cathode connector and an anode connector configured to generate a voltage therebetween when the active surfaces of the PV cells are exposed to light; a circuit board connected to at least one of the cathode connector and the anode connector, the circuit board having a plurality of openings therein; an output connector configured to electrically connect the circuit board to a load, A power receiver, wherein each PV cell is positioned to receive light that has passed through at least one of the plurality of openings in the circuit board. <Claim 29> 30. The power receiver of claim 28, further comprising a reflector associated with at least one PV cell of the plurality, the reflector configured to reflect light onto the active surface of the at least one associated PV cell. <Claim 30> 30. The power receiver of claim 28, further comprising a plurality of reflectors, each reflector associated with at least one PV cell of the plurality, each reflector configured to reflect light onto the active surface of the at least one associated PV cell. <Claim 31> 31. The power receiver of claim 30, wherein at least some members of the plurality of reflectors are disposed within the opening in the circuit board. <Claim 32> 30. The power receiver of claim 28, wherein the circuit board includes traces configured to connect the first subset of PV cells in parallel. <Claim 33> 33. The power receiver of claim 32, wherein the traces configured to connect the first subset of the PV cells in parallel are disposed on a first layer of the circuit board. <Claim 34> 33. The power receiver of claim 32, wherein the circuit board includes wiring configured to connect a second subset of the PV cells in parallel, the second subset and the first subset having no PV cells in common. <Claim 35> wiring configured to connect the first subset of the PV cells in parallel is disposed on a first layer of the circuit board; 35. The power receiver of claim 34, wherein traces configured to connect the second subset of the PV cells in parallel are disposed on a second layer of the circuit board different from the first layer. <Claim 36> 35. The power receiver of claim 34, wherein the circuit board further includes wiring configured to connect the first subset to the second subset in series, thereby generating a voltage approximately equal to the sum of a first voltage between the cathode connectors and anode connectors of the PV cells of the first subset and a second voltage between the cathode connectors and anode connectors of the PV cells of the second subset. <Claim 37> 30. The power receiver of claim 28, wherein all electrical connections between different PV cells of the plurality include traces within the circuit board. <Claim 38> 30. The power receiver of claim 28, wherein the circuit board is configured to dynamically change connections between different PV cells. <Claim 39> 30. The power receiver of claim 28, further comprising a heat sink configured to remove waste heat from the PV cell. <Claim 40> 40. The power receiver of claim 39, wherein the heat sink has a surface that serves as a reference surface for positioning optical components of the power receiver. <Claim 41> a heat sink including a first side, a second side, and an opening passing from the first side to the second side; a current collecting device in thermal contact with the first side of the heat sink; an electronic component disposed on the second side of the heat sink; an electrical connector disposed within the opening in the heat sink, the electrical connector connecting the current collecting device to the electronic component. <Claim 42> 42. The power receiver of claim 41, wherein the heat sink is fabricated from a thermally conductive material. <Claim 43> 43. The power receiver of claim 42, wherein the thermally conductive material is a metal or a ceramic. <Claim 44> 42. The power receiver of claim 41, wherein the current collecting device is a photovoltaic (PV) cell. <Claim 45> 42. The power receiver of claim 41, wherein the heat sink includes an internal channel configured for circulation of a cooling fluid. <Claim 46> 42. The power receiver of claim 41, wherein the heat sink includes a vapor chamber. <Claim 47> 42. The power receiver of claim 41, wherein the heat sink includes a plurality of openings passing from the first side to the second side, and the power receiver further comprises a plurality of electrical connectors disposed with the openings in the heat sink. <Claim 48> 48. The power receiver of claim 47, further comprising a plurality of current collecting devices mounted on the first side of the heat sink, the plurality of electrical connectors connecting a respective one of the plurality of current collecting devices to the electronic component mounted on the second side of the heat sink.

Claims

1. a plurality of photovoltaic (PV) cells disposed on a support surface, the PV cells being divided into a plurality of voltage groups, each voltage group having a selected output voltage and output current; Electrical wiring for interconnecting the PV cells, the wiring comprising: connecting each PV cell in a voltage group in parallel; the electrical wiring configured to connect each voltage group in series with at least one other voltage group; 1. A power receiver comprising: the PV cells of each voltage group are arranged so that they are not adjacent to one another on the support surface; the plurality of voltage groups exhibiting a current mismatch of less than 5%; A power receiver, wherein current mismatch is defined as the difference between the maximum and minimum output current divided by the average output current when said receiver is exposed to a power beam.

2. 10. The power receiver of claim 1, wherein the power beam is a laser power beam.

3. 10. The power receiver of claim 1, wherein the power beam has a substantially Gaussian beam profile.

4. 10. The power receiver of claim 1, wherein the power beam has a super-Gaussian beam profile.

5. 2. The power receiver of claim 1, wherein the current mismatch is less than 4%.

6. 2. The power receiver of claim 1, wherein the current mismatch is less than 3%.

7. 2. The power receiver of claim 1, wherein the current mismatch is less than 2%.

8. 2. The power receiver of claim 1, wherein the current mismatch is less than 1%.

9. The power receiver of claim 1 , wherein the PV cells are arranged in a rectangular shape.

10. The power receiver of claim 1 , wherein the PV cells are arranged in a square.

11. The power receiver of claim 1 , wherein the PV cells are arranged in a square with corners truncated.

12. The power receiver of claim 1 , wherein the PV array includes four voltage groups.

13. The power receiver of claim 1 , wherein the PV array includes five voltage groups.

14. The power receiver of claim 1 , wherein the PV array includes six voltage groups.

15. a plurality of photovoltaic (PV) cells arranged on a support surface to form a PV array, the PV cells being divided into a plurality of voltage groups; Electrical wiring for interconnecting the PV cells, the wiring comprising: connecting each PV cell in a voltage group in parallel; the electrical wiring configured to connect each voltage group in series with at least one other voltage group; 1. A power receiver comprising: A power receiver, wherein the PV cells of each voltage group are arranged in a repeating pattern along a first axis of the PV array, and the repeating pattern is staggered along a second axis of the PV array by an offset value, and the offset value is selected so that PV cells within the same voltage group are not adjacent to each other.

16. 16. The power receiver of claim 15, wherein the PV cells are connected in series with one or more adjacent PV cells along the first axis, and the PV cells belonging to each voltage group are connected in parallel by additional wiring.

17. The power receiver of claim 16 , wherein the additional wiring is disposed within the support surface.

18. The power receiver of claim 16 , wherein the additional wiring is disposed behind the support surface.

19. 17. The power receiver of claim 16, wherein the additional wiring is disposed in a circuit board having openings positioned to allow light to pass through to reach the PV cells.

20. The power receiver of claim 15 , wherein the PV cells are arranged to form a rectangle.

21. The power receiver of claim 15 , wherein the PV cells are arranged to form a square.

22. 16. The power receiver of claim 15, wherein the PV cells are arranged to form a square with truncated corners.

23. The power receiver of claim 15 , wherein the PV array includes four voltage groups.

24. The power receiver of claim 15 , wherein the PV array includes five voltage groups.

25. The power receiver of claim 15, wherein the PV array includes between 6 and 16 voltage groups.

26. a plurality of photovoltaic (PV) cells arranged on a support surface to form a PV array, the PV cells being divided into a plurality of voltage groups; Electrical wiring for interconnecting the PV cells, the wiring comprising: connecting each PV cell in a voltage group in parallel; the electrical wiring configured to connect each voltage group in series with at least one other voltage group; 1. A power receiver comprising: A power receiver, wherein each voltage group has the property that a Voronoi mesh generated from the locations of PV cells in the voltage group has a median Voronoi cell aspect ratio of less than 1.

4.

27. 27. The power receiver of claim 26, wherein each voltage group has the property that a Voronoi mesh generated from the locations of PV cells in the voltage group has a median Voronoi cell aspect ratio of less than 1.

3.

28. A plurality of photovoltaic (PV) cells, each PV cell comprising: an active surface configured to receive light for conversion to electrical power; the plurality of photovoltaic cells having cathode and anode connectors configured to generate a voltage therebetween when the active surfaces of the PV cells are exposed to light; a circuit board connected to at least one of the cathode connector and the anode connector, the circuit board having a plurality of openings therein; an output connector configured to electrically connect the circuit board to a load; 1. A power receiver comprising: A power receiver, wherein each PV cell is positioned to receive light that has passed through at least one of the plurality of openings in the circuit board.

29. 30. The power receiver of claim 28, further comprising a reflector associated with at least one PV cell of the plurality, the reflector configured to reflect light onto the active surface of the at least one associated PV cell.

30. 30. The power receiver of claim 28, further comprising a plurality of reflectors, each reflector associated with at least one PV cell of the plurality, each reflector configured to reflect light onto the active surface of the at least one associated PV cell.

31. 31. The power receiver of claim 30, wherein at least some members of the plurality of reflectors are disposed within the opening in the circuit board.

32. 30. The power receiver of claim 28, wherein the circuit board includes traces configured to connect the first subset of PV cells in parallel.

33. 33. The power receiver of claim 32, wherein the traces configured to connect the first subset of the PV cells in parallel are disposed on a first layer of the circuit board.

34. 33. The power receiver of claim 32, wherein the circuit board includes traces configured to connect a second subset of the PV cells in parallel, the second subset and the first subset having no PV cells in common.

35. traces configured to connect the first subset of the PV cells in parallel are disposed on a first layer of the circuit board; 35. The power receiver of claim 34, wherein traces configured to connect the second subset of PV cells in parallel are disposed on a second layer of the circuit board different from the first layer.

36. 35. The power receiver of claim 34, wherein the circuit board further includes wiring configured to connect the first subset to the second subset in series, thereby generating a voltage approximately equal to the sum of a first voltage between the cathode connectors and anode connectors of the PV cells of the first subset and a second voltage between the cathode connectors and anode connectors of the PV cells of the second subset.

37. 30. The power receiver of claim 28, wherein all electrical connections between different PV cells of the plurality include traces within the circuit board.

38. 30. The power receiver of claim 28, wherein the circuit board is configured to dynamically change connections between different PV cells.

39. 30. The power receiver of claim 28, further comprising a heat sink configured to remove waste heat from the PV cell.

40. 40. The power receiver of claim 39, wherein the heat sink has a surface that serves as a reference surface for positioning optical components of the power receiver.

41. a heat sink including a first side, a second side, and an opening passing from the first side to the second side; a current collecting device in thermal contact with the first side of the heat sink; an electronic component disposed on the second side of the heat sink; an electrical connector disposed within the opening in the heat sink, the electrical connector connecting the current collecting device to the electronic component.

42. 42. The power receiver of claim 41, wherein the heat sink is fabricated from a thermally conductive material.

43. 43. The power receiver of claim 42, wherein the thermally conductive material is a metal or a ceramic.

44. 42. The power receiver of claim 41, wherein the current collecting device is a photovoltaic (PV) cell.

45. 42. The power receiver of claim 41, wherein the heat sink includes an internal channel configured for circulation of a cooling fluid.

46. 42. The power receiver of claim 41, wherein the heat sink includes a vapor chamber.

47. 42. The power receiver of claim 41, wherein the heat sink includes a plurality of openings passing from the first side to the second side, and the power receiver further comprises a plurality of electrical connectors disposed with the openings in the heat sink.

48. 48. The power receiver of claim 47, further comprising a plurality of current collecting devices mounted on the first side of the heat sink, the plurality of electrical connectors connecting a respective one of the plurality of current collecting devices to the electronic component mounted on the second side of the heat sink.

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