Zone inverters for photovoltaic systems.

Abstract

Techniques are disclosed for converting electricity generated by a photovoltaic cell into AC or DC output power. In some examples of the disclosed techniques, a zonal power inverter includes a plurality of voltage converters, the outputs of which are connected in series and electrically isolated from one another except for the output terminals of the voltage converters being connected in series. The power inverter may further include a DC / AC converter coupled to a positive output terminal of one of the voltage converters. In some examples, an isolated multi-junction photovoltaic cell includes a plurality of photosensitive semiconductor active layers, each of which is electrically isolated from the other active layers and formed from a respective material having a different bandgap than the other active layers. In some examples, the multi-junction photovoltaic cell is coupled to an input of a zonal power inverter.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of an earlier filing date of U.S. Provisional Application No. 63 / 308,458, filed February 9, 2022, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Many photovoltaic (PV) circuits include silicon PV cells, which are single junction (SJ) or first generation semiconductor devices. PV circuits are fabricated with a transparent top surface, sealing membranes above and below the electrically connected PV cells, a back surface, and a frame around the outer edge. This structure protects the PV module from the environment, prevents electric shock, and reduces heat transfer from the PV cells to the environment. Under controlled test standards, the best research PV cell efficiency is about 27%. Due to differences in PV housings, energy calculation methodologies, and cell inconsistencies, module efficiencies are about 2-4% lower than their single cell efficiencies. Typically, PV modules operate within a temperature range of 15-65°C. As the temperature of the PV cells increases, the efficiency decreases by about 0.4% per degree Celsius. Thus, a PV cell at 50°C has 10% less power efficiency than at 25°C. Thus, when deployed in the field, a PV panel operates at less than 20% efficiency. Thus, there is ample room for improvement in the construction and use of PV cells and PV modules. Summary of the Invention [Means for solving the problem]

[0003] A method and apparatus for converting electricity generated by a photovoltaic cell into alternating current (AC) or direct current (DC) output power is disclosed.

[0004] In some examples of the disclosed technology, the zone power inverter includes a plurality of voltage converters, the outputs of which are connected in series, each of the voltage converters being electrically isolated from one another except for the output terminals of the voltage converters being connected in series. The power inverter may further include a DC / AC converter coupled to a positive output terminal of one of the voltage converters and a negative output terminal of one of the voltage converters. The power inverter may further include a plurality of photovoltaic (PV) cells, each of the PV cells having a cathode coupled to an input of a respective one of the voltage converters. The power inverter may further include a controller coupled to a respective control input of the voltage converter switches, the controller being programmed to modulate each of the respective control inputs to regulate an output voltage at a respective output terminal of the voltage converters.

[0005] In some examples of the apparatus, at least one of the voltage converters is a flyback DC / DC converter. In some examples, the apparatus further comprises a transformer and a switch operated by the controller to modulate operation of its respective power converter.

[0006] In some examples of the disclosed technology, a method of operating a zonal power converter includes modulating, by a controller, an input signal to a plurality of series-coupled voltage converters, each of the plurality of voltage converters being electrically isolated except for the series coupling and configured to receive power from a respective photovoltaic (PV) cell of a plurality of photovoltaic cells.

[0007] In some examples of the disclosed technology, an insulated multijunction photovoltaic (PV) cell includes multiple photosensitive semiconductor active layers, each of which is electrically isolated from the other active layers and is formed from a respective material having a different bandgap than the other active layers. In some examples, the PV cell includes at least one of an active layer including at least one of boron phosphide, selenium, La2CuO2, or gallium indium phosphide, an active layer including at least one of gallium arsenide, cadmium telluride, or copper zinc tin sulfide, an active layer including at least one of silicon, tin sulfide, or Zn3As2, or an active layer including at least one of germanium, indium nitride, or gallium antimonide. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a system including a power inverter for use with photovoltaic cells, as may be implemented in certain examples of the disclosed technology. [Figure 2A] 1 is a simplified diagram of a photovoltaic converter system that may be implemented in certain examples of the disclosed technology. [Figure 2B] 1 is a simplified diagram of a photovoltaic converter system that may be implemented in certain examples of the disclosed technology. [Diagram 3] 1 is a cross-sectional view (not to scale) illustrating a multi-junction photovoltaic cell that may be implemented in certain examples of the disclosed technology. [Figure 4] FIG. 1 is a plan view of a semiconductor wafer illustrating an exemplary arrangement of fingers / trenches and bus bars that may be implemented in certain examples of the disclosed technology. [Diagram 5] 1 illustrates a cross-section of a region of a PV cell with via regions used to electrically connect a busbar to the top surface of the cell so that the cell may be connected to a voltage converter. As shown, each of the vias connects to a different layer of the busbar, and thereby to a different respective terminal of the photodiode. [Figure 6]1 illustrates a cross-section of a multijunction PV cell and shows the via areas at the edge of the wafer, which connect each side of the active area to the top surface of the cell. [Figure 7] Illustrates a cross section of a multi-junction PV cell. The PV cell is formed by separately fabricating a set of glass, TCO, and active photodiode layers and combining them with a junction layer. The external leads of each junction connect to an independent electrically isolated DC-DC converter. [Figure 8] 1 is a chart plotting voltage across a photodiode on the x-axis versus current density on the y-axis for three different photodiode materials. [Figure 9] 1 is a chart plotting the power output of a photovoltaic cell versus the voltage across a photodiode. [Figure 10] 1 is a flowchart outlining an example method of operating a power converter with a controller. [Figure 11] 1 illustrates a generalized example of a suitable computing environment in which the described embodiments, techniques, and technologies may be implemented, including implementing a microcontroller for a power inverter. [Figure 12] 1 is a simplified diagram of a photovoltaic converter system including a multi-input transformer that may be implemented in certain examples of the disclosed technology. [Figure 13] 1 is a simplified diagram of a photovoltaic converter system including a group of multiple drivers, as may be implemented in certain examples of the disclosed technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] I. General Considerations This disclosure has been described in the context of representative embodiments which are not intended to be limiting in any way.

[0010] As used in this application, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Additionally, the term "comprises" means "comprising." Furthermore, the term "coupled" encompasses electrical and magnetic methods of coupling or connecting items together and does not exclude the presence of intermediate elements between the coupled items. Additionally, as used herein, the term "and / or" refers to any one item or combination of items in the phrase.

[0011] The systems, methods, and devices described herein should not be construed as limiting in any way. Instead, the present disclosure is directed to all novel and non-obvious features and aspects of the various disclosed embodiments, both alone and in various combinations and subcombinations with each other. The disclosed systems, methods, and devices are not limited to any particular aspect or feature or combination thereof, and the disclosed objects and methods do not require that any one or more particular advantages exist or problems be solved. Moreover, any features or aspects of the disclosed embodiments can be used in various combinations and subcombinations with each other.

[0012] Although some operations of the disclosed methods are described in a particular sequential order for convenience of presentation, it should be understood that the methods of the description encompass reordering, unless a particular ordering is required by specific language described below. For example, operations described in sequence may be reordered in some cases or performed simultaneously. Furthermore, for simplicity, the accompanying figures may not show the various ways in which the disclosed items and methods can be used in combination with other items and methods. In addition, the description may use terms such as "produce," "generate," "output," "receive," "follow," "select," and "output" to describe the disclosed methods. These terms are rough descriptions of actual operations that are performed. The actual operations that correspond to these terms will vary depending on the specific implementation and are readily discernible by those of ordinary skill in the art.

[0013] Any theories of operation, scientific principles, or other theoretical explanations presented herein with reference to the devices or methods of the present disclosure are provided for purposes of improved understanding and are not intended to limit the scope, and the devices and methods in the appended claims are not limited to devices and methods that function in a manner described by such theories of operation.

[0014] Any of the disclosed methods can be implemented as computer-executable instructions stored on one or more computer-readable media (e.g., computer-readable media such as one or more optical media disks, volatile memory components (such as DRAM or SRAM), or non-volatile memory components (such as hard drives)) and executed on a computer (e.g., any commercially available computer including a smart phone or other mobile device that includes computing hardware). Any of the computer-executable instructions for implementing the disclosed techniques, as well as any data created and used during the implementation of the disclosed embodiments, can be stored on one or more computer-readable media (e.g., computer-readable storage media). The computer-executable instructions can be, for example, part of a dedicated software application, or a software application accessed or downloaded via a web browser or other software application (such as a remote computing application). Such software can be executed, for example, on a single local computer (e.g., with a general-purpose and / or dedicated processor running on any suitable commercially available computer) or in a networked environment using one or more networked computers (e.g., via the Internet, a wide area network, a local area network, a client-server network (such as a cloud computing network), or other such network).

[0015] For clarity, only certain selected aspects of the software-based implementation are described. Other details well known in the art are omitted. For example, it should be readily understood by those skilled in the art having the benefit of this disclosure that the disclosed technology is not limited to any particular computer language or program. For example, the disclosed technology can be implemented by software written in C, C++, Java, or any other suitable programming language. Similarly, the disclosed technology is not limited to any particular computer or hardware type. Specific details of suitable computers and hardware are well known and need not be described in detail in this disclosure.

[0016] Additionally, any of the software-based embodiments (e.g., including computer-executable instructions for causing a computer to perform any of the disclosed methods) may be uploaded, downloaded, or remotely accessed via suitable communications means including, for example, the Internet, the World Wide Web, an intranet, a software application, cable (including fiber optic cable), magnetic communication, electromagnetic communication (including RF, microwave, and infrared communication), electronic communication, or other such communications means.

[0017] II. Introduction to the Disclosed Technology Methods and apparatus are disclosed for converting electricity generated by a photovoltaic cell into AC or DC output power. Photovoltaics uses photovoltaic cells to directly convert solar radiation into electrical energy. Incident photons can be absorbed in a semiconductor material (e.g., a PV cell), which excites electrons from the valence band to the conduction band and holes from the conduction band to the valence band, respectively, to generate charge. A PN junction separates the electrons and holes in the PV cell to generate voltage and power.

[0018] Photovoltaic cells can be combined into a "PV module." A PV module electrically connects multiple individual PV cells to increase the total output voltage and power. The generated DC output power can be connected to an inverter (e.g., a microinverter) that converts the DC output power to a desired AC signal. PV module efficiency depends on the IV characteristics of each cell, the maximum power point (MPP) of the composite PV cell, and the DC-AC conversion methodology. Photovoltaic cell efficiency can be reduced due to factors including increased PV cell temperature, higher variability of incident radiation, and cell defects or failure modes. These factors can affect the I of each cell. sc (short circuit current) and V oc When PV cells or modules are electrically connected in series, the total current through the circuit is the lowest I sc which reduces the overall output power.

[0019] In some examples of the disclosed technology, multi-junction solar cells are used. A multi-junction (MJ) solar cell is a vertical stack of several semiconductor PN junctions, each with a different bandgap. Incident radiation is first absorbed by the top layer with the largest bandgap. Unabsorbed lower frequency radiation propagates to lower layers with successively lower bandgaps. Compared to a single junction cell, each layer or PN junction of an MJ solar cell converts energy of a range of wavelengths more efficiently.

[0020] The effect of current mismatch between PV cells or PV modules is reduced by using PV cells or similar I sc This can be reduced by selecting / modifying the layers of the multijunction cells to have a current mismatch. Existing PV panel designs do not allow for direct, uninsulated cooling of heated PV cells. Zonal (zonal) energy extraction from the PV cells eliminates this current mismatch and allows for direct thermal cooling of the cells.

[0021] In some examples of the disclosed technology, the PV cells can provide a charge output to an electrically isolated DC-DC converter, with each PV cell or zone (e.g., in a multi-junction cell) connected to its own converter. In some examples, the DC-DC converter is a flyback converter. The converter outputs are connected in series. Each of the converters has a flyback or boost switch that oscillates in response to an input signal. The switches can be implemented, for example, using depletion mode transistors or microelectromechanical (MEM) switches. In other examples, relays are used. For example, a microcontroller can vary the duty cycle of the input signal using pulse width modulation, thus controlling the output voltage of the converter. It is often desirable to operate the converter at or near its maximum power point by adjusting the input signal. As will be readily understood by those skilled in the art having the benefit of this disclosure, the output voltage associated with the maximum power point will change dynamically as the operating conditions of the PV cells and the load change over time. Thus, the target output voltage is dynamically adjusted over time (e.g., using perturbations to observe operation, as discussed further below). By using a DC-DC converter configured as described in certain examples herein, each PV cell may be allowed to operate at or near their maximum current and is not limited by the minimum operating current of the connected PV cells.

[0022] The power from the series connected converter outputs can then be transferred to a DC battery system or a DC / AC converter, for example, an H-bridge converter can be used to convert the DC power to an AC signal.

[0023] III. Exemplary Converter Systems FIG. 1 is a block diagram of a system including a power inverter 100 for use with photovoltaic cells that may be implemented in certain examples of the disclosed technology. A plurality of photovoltaic cells or zones 110 are shown. In some examples, single-junction photovoltaic cells are used. In other examples, multi-junction photovoltaic cells are used. Each cell or zone of multi-junction photovoltaic cells has an output connected to an input terminal of one of the voltage converters 120 shown. The voltage converter may be any suitable DC-DC converter with electrical isolation, including any combination of the following types of converters: flyback, isolated CUK, isolated SEPIC (single-ended primary inductor converter), Zeta (inverted SEPIC), push-pull, forward, dual active bridge (DAB), dual half-bridge, half full-bridge, or multi-port DAB. The voltage converters 120 have their outputs connected in series. The first and last voltage converter outputs are connected to the input terminals of a DC / AC converter 130. The DC / AC converter outputs an AC waveform to an inverter load 140.

[0024] Each of the voltage converters 120 receives an input signal from a controller 150. The controller 150 modulates the input signal to each converter to control when the circuit to each PV cell is completed. The input signal is modulated to optimize the power output of each individual PV cell. The voltage converters are otherwise isolated from each other. Because of this isolation, the current output of the voltage converter stack is not limited by any one particular PV cell. The controller 150 can also communicate with wired or wireless communication networks and other hardware using a communication module 160. In some examples, the controller is a dedicated PID or PI controller, a microcontroller, a microprocessor field programmable gate array (FPGA), or an ASIC-based controller.

[0025] The controller and power electronics for one or more PV cells or zones may be combined into a PV module. For example, the components may be mounted on a printed circuit board (PCB). As would be readily understood by one of ordinary skill in the art having the benefit of this disclosure, the PCB may have additional switches and diodes for each PV zone, which may be packaged with the module. The module may further include an electromagnetic interference (EMI) suppression filter at the output of the AC converter. The PV module may include integrated arc fault protection and rapid shutdown features for compliance with applicable electrical standards. Because the PV cells or zones are electrically isolated, the cells may be cooled by gas or liquid (e.g., air or water) applied to the PV cell package without creating a short circuit through the coolant.

[0026] IV. AN EXEMPLARY ZONE INVERTER SYSTEM USING FLYBACK CONVERTERS 2A and 2B are simplified diagrams of a photovoltaic converter system 200 that may be implemented in a particular example of the disclosed technology. As shown, there are three flyback converter units 210, 211, 212. Each of the converter units is coupled to a photovoltaic cell that generates an electric charge in response to incident photons received at the active layer(s) of the cell. The photovoltaic cell acts as a variable DC voltage source. This voltage source is coupled to a primary coil of a transformer. The other end of the primary coil is connected to a switch. When the switch is closed, a circuit is completed to the other terminal of the PV cell.

[0027] Each of the flyback converters 210, 211, 212 are electrically isolated from one another. As shown, each PV cell or PV zone connects only to its respective voltage converter. When a flyback converter switch is open, the respective PV cell is not electrically connected to its transformer. A controller 230 modulates the input signal to each of the flyback converter switches to open and close the switch. The controller attempts to optimize the power output of each PV cell, as described in more detail below. The controller 230 also modulates the input to the DC / AC converter. In this example, an H-bridge type DC / AC converter 220 is used, but other DC / AC converter circuits may be used, as would be readily understood by one of ordinary skill in the art. For example, a cascaded H-bridge converter may provide the DC / AC converter. The illustrated DC / AC converter includes four switches 221-224 and is coupled to an AC output load 240.

[0028] In some examples, the controller is a processor or microcontroller that executes computer readable instructions stored in a memory. In other examples, a finite state machine or other control logic is provided by custom circuitry or programmable logic. The controller may be configured to measure the combined output DC signal of the series DC / DC converters, or to measure the output voltage and / or current of each individual converter. As will be readily appreciated by one of ordinary skill in the art having the benefit of this disclosure, the controller may use any suitable technique for controlling the operation of the converters, such as a proportional integral derivative (PID) technique or a proportional integral (PI) technique.

[0029] If the controller is configured to measure the combined output DC signal, the controller may generate separate pulse width modulation (PWM) signals to each of the flyback switches. During a certain period of time, the controller will adjust the PWM signal to one of the flyback switches and measure the total output power. All other flyback switches will retain their previous PWM signals. Using a perturbation and observation algorithm, the controller system will determine the next PWM signal for another of the flybacks. In some examples, the controller will continue to adjust the PWM until the MPP is found for the current switch. Then, the controller will proceed to find a new MPP for the next flyback switch. The controller will incrementally drive to the MPP of each PV zone.

[0030] In another configuration, the controller reads the relative voltage of each zone output. Hall current sensors measure each output current, which is then read by the controller. The controller generates a control signal (e.g., PWM signal) for each flyback switch. The controller repeatedly reads the voltage and current of each zone (calculate the power). The system can then adjust the control signal for each flyback switch separately. For example, a perturb and observe technique can be used to select the control signal that will operate the converter so that the PV cell is operating at or near its maximum power point.

[0031] Referring to FIG. 2B, further details of one of the flyback converters 210 are shown. The terminal of the PV cell is coupled to a first terminal of the primary coil of the transformer 260. The second terminal of the primary coil is electrically connected to a switch 270. The switch can be, for example, a field effect transistor (FET), such as a metal oxide semiconductor FET (MOSFET), for example a depletion mode or enhancement mode FET or MOSFET. Using such a transistor may be desirable to avoid voltage loss across the source / drain (or collector / emitter) of the FET when the device is active. The source of the switch transistor connects to the second terminal of the primary coil of the transformer and the drain connects to the negative terminal of the PV cell 250. The flyback converter 210 further includes a diode 280 connected to the first terminal of the secondary coil of the transformer 260 and providing an output voltage to the individual flyback converter. A capacitor 290 is provided between the output terminals of the flyback converter. In some examples, a flyback converter may be implemented using another switch, or a diode and a switch in parallel, configured to operate in antiphase to switch 270. In some examples, switch 270 is included in the circuit in the illustrated alternative location 271 between the output of the PV cell and the upper coil of the primary input of transformer 260.

[0032] V. Exemplary Multijunction Photovoltaic Cells FIG. 3 is a cross-sectional view (not to scale) illustrating a multi-junction photovoltaic cell 300 that may be implemented in certain examples of the disclosed technology. As shown, the cell includes multiple layers of silicon dioxide 311-313 and transparent conductive oxide (TCO) 321-327. The cell also includes several active layers 331-334 that form photodiodes. In this example, the planes of the active layers form the cathode and anode terminals of the photodiodes. The terminals of the photodiodes are in electrical contact with metal conductors as shown. The conductors may be made of aluminum, silver, or copper, for example, with an anti-diffusion liner. A portion of the conductors forms trench-shaped fingers (e.g., trench-shaped fingers 341, 342 formed from at least one of aluminum, silver, or copper) within the active layers or insulating silicon dioxide layers. Bus bars (or "conductor buses") (e.g., bus bars 351, 352) are shown in dashed lines and are sandwiched between the layers as shown in FIG. 3.

[0033] The materials of the active layers are selected to have non-overlapping bandgaps. This helps improve power output since each of the active layers is sensitive to a particular frequency range of electromagnetic energy (e.g., a range of the visible or ultraviolet light spectrum). In the illustrated example, four photovoltaic active layers are shown. The first active layer 331 is a semiconductor formed from at least one of boron phosphide, selenium, La2CuO2, or gallium indium phosphide. The second active layer 332 is a semiconductor formed from at least one of gallium arsenide, cadmium telluride, or copper zinc tin sulfide (CZTS). The third active layer 333 is a semiconductor formed from at least one of silicon, tin sulfide, or Zn3As2. The fourth active layer 334 is a semiconductor formed from at least one of germanium, indium nitride, or gallium antimonide. As would be readily understood by one of ordinary skill in the art having the benefit of this disclosure, any suitable combination of active layers can be selected for a multi-junction PV cell. For example, some cells may have only one of the aforementioned active layers, or a combination of two, three, or four of the aforementioned active layers. The thicknesses of the semiconductor layers are selected to maximize light absorption in a particular frequency range and minimize reflection between the layers.

[0034] The silicon dioxide layers 311-313 provide insulation between layers disposed above and below the insulating layer. The silicon dioxide layers 311-313 further provide structural support for the active layers. The TCO layers 321-327 form a conductive plane on the surface of each active layer 331, 332, 333, 334, but also allow light to transmit through the TCO layers. In this example, the multi-junction device includes an anti-reflective coating (ARC) 361 on the top layer and a conductive planar layer 362 on the bottom layer (formed, for example, from aluminum or silver).

[0035] As will be readily understood by one of ordinary skill in the art having the benefit of this disclosure, in other examples, additional electrically isolated active photovoltaic layers can be used in a multijunction cell beyond the four active layers shown in Figure 3. In some examples, a multijunction cell includes only a single active layer, a pair of active layers, or a triplet of active layers as shown in Figure 3.

[0036] 4 is a plan view of a semiconductor wafer 400 illustrating an exemplary arrangement of fingers / trenches 410 and bus bars 420 that may be implemented in certain examples of the disclosed technology. The wafer further includes an outer ring bus bar 430 as shown.

[0037] An example of the manufacture of a multi-junction cell will now be described. As will be readily understood by those of ordinary skill in the art having the benefit of this disclosure, the manufacturing process can be adapted depending on the particular cell being manufactured.

[0038] A silicon substrate is provided and cleaned.

[0039] · Resist is deposited and mechanically aligned with the wafer edge notch.

[0040] Metal trenches and busbars are mechanically patterned (e.g., using imprint lithography) Reactive ion etching (RIE) is used to transfer the pattern into the Si material. The resist and etch by-products are removed.

[0041] These etched structures are then filled with a liner / metal and the overburden metal is polished away. The liner prevents diffusion of the metal into the semiconductor material.

[0042] A transparent conductive oxide (TCO) layer is deposited.

[0043] A layer of glass is then deposited.

[0044] Next, resist is deposited. The wafer is mechanically aligned with the first trench patterning.

[0045] Metal trenches and busbars are mechanically patterned.

[0046] The pattern is transferred to the glass by reactive ion etching (RIE). The resist and etch by-products are removed. These etched structures are then filled with metal and the overburden metal is polished away.

[0047] Next, a TCO layer is deposited.

[0048] A P-doped semiconductor with a larger bandgap than the layer below is deposited, followed by the same semiconductor with N-doping. This creates a PN junction that forms the photodiode. Any of the layers described for the active layer in Figure 3 can be used to form a photodiode.

[0049] Next, resist is deposited. The wafer is mechanically aligned with the previous trench patterning. Metal trenches and busbars are mechanically patterned.

[0050] RIE is used to etch a pattern into a semiconductor. Resist and etch by-products are removed. These etched structures are then filled with a liner and metal. The overburden metal is polished away.

[0051] Next, a TCO layer is deposited.

[0052] A layer of glass is then deposited.

[0053] Higher layers can then be built up by repeating the previous steps of depositing a glass layer, forming trenches and busbars, depositing a TCO layer, and forming the photodiode active layer.

[0054] For the top layer with the largest bandgap material, an anti-reflective coating (ARC) is applied over the top TCO layer.

[0055] After the top active layer (e.g. the first three active layers described with reference to FIG. 3) has been formed, the wafer may be flipped over and the front surface cleaned again.

[0056] · Different active layers can be formed: first a TCO layer, then a glass layer is deposited.

[0057] The resist is deposited.

[0058] The wafer is mechanically aligned with the trench patterning on the other side.

[0059] Metal trenches and busbars are mechanically patterned.

[0060] The pattern is etched into the Si through the glass by RIE. The resist and etching by-products are removed.

[0061] These etched structures are then filled with a liner and metal. The overburden metal is polished away.

[0062] Another layer of glass is deposited.

[0063] The wafer is mechanically aligned with the previous trench patterning.

[0064] Metal trenches and busbars are mechanically patterned.

[0065] The pattern is etched into the glass by RIE. The resist and etching by-products are removed.

[0066] These etched structures are then filled with metal and the overburden metal is polished away.

[0067] A TCO layer is deposited.

[0068] A fourth active layer is formed by depositing an N-type doped semiconductor and then depositing the same semiconductor with P-type doping.

[0069] A metal film (e.g. aluminum or silver) is painted or deposited onto the last layer.

[0070] 5 shows a cross-sectional view of a region of a multijunction PV cell 500 with via regions used to electrically connect a bus bar (shown in dashed lines such as reference numeral 510) to the top surface of the cell so that the cell may be connected to a voltage converter. As shown, each of the vias 520 connects to a different layer of the bus bar, and thereby to a different respective terminal of the photodiode. The layers shown are constructed and arranged similarly to those described above with respect to FIG. 3. As will be readily understood by one of ordinary skill in the art having the benefit of this disclosure, the composition, number, and arrangement of the layers within a PV cell can be varied in a similar manner as described above.

[0071] 6 shows a via area 620 at the edge of a wafer 600. The vias can be formed after fabricating the PV cells by the following actions.

[0072] The wafer is flipped again and aligned.

[0073] Large vias are patterned on the wafer edge. Multi-step RIE cuts through various layers of insulating and semiconducting materials. The via etch will stop when it contacts the edge metal busbar. Other vias will continue etching until the desired edge busbar is reached.

[0074] · In an alternative example, laser etching is used to drill vias down to the various layer busbars.

[0075] The wafer is cleaned. A thin oxide is deposited on the via sides and busbars. A RIE anisotropic etch destroys the oxide on the via bottom. Metal filling of the via and electrical connection can be made to PCB metal lines.

[0076] FIG. 7 shows a cross section of a multi-junction PV cell 700. The PV cell is formed by separately fabricating sets of glass, TCO, and active photodiode layers 740-743 and combining bonding layers. In this example, each set of bonding layers 710, 711, 712, 713 is fabricated separately on a sheet of thin film. For example, bonding layer set 710 includes TCO layers 721, 722, insulating layer 725, and active photodiode layer 740. The bonding layer sets are positioned on top of each other and aligned. Similar to that discussed in FIG. 3, conductors form trench-shaped fingers (e.g., trench-shaped fingers 731 formed from at least one of aluminum, silver, or copper) in the active layers or insulating silicon dioxide layers. Bus bars (e.g., bus bar 735) are shown in dashed lines and are sandwiched between the layers as shown. External leads 750 are connected to either end of the bonding layers (e.g., as shown at 760, 761 for bonding layer set 710) or the PV cell backside (790). After the layers are aligned, a vacuum seal and adhesive sealant are applied to the PV cell. An anti-reflective coating 780 can be applied to the first bonding layer set 710.

[0077] The metal trenches in multijunction PV cells can be made from silver, aluminum, or copper. After etching the trench into the semiconductor material, the bottom of the trench can be implanted with an N-type dopant on the N-side and a P-type dopant on the P-side of the semiconductor layer before metal fill.

[0078] The insulating layers (e.g., glass, SiO2) provide electrical insulation between the semiconductor layers. Other wide bandgap dielectric materials can also be used. The dielectric constant of each insulating layer will be selected to minimize optical reflection at the interface layers.

[0079] In various examples, the disclosed multi-junction PV cells can have 4 to 6 different bandgaps. In one example, a 5-junction PV cell can be fabricated with active layer materials having a 0.73 eV bandgap (GaSb) or a 0.67 eV bandgap (Ge), a 1.12 eV bandgap (Si), a 1.43 eV bandgap (GaAs), a 1.68 eV bandgap (CuGaSe2), and a 2.1 eV (GaInP). In another example, a six-junction PV cell can be fabricated with active layer materials having a 0.73 eV bandgap (GaSb) or a 0.67 eV bandgap (Ge), a 0.91 eV bandgap (Cu2SnS3), a 1.12 eV bandgap (Si), a 1.43 eV bandgap (GaAs), a 1.68 eV bandgap (CuGaSe2), and a 2.1 eV bandgap (GaInP).

[0080] In some examples, the disclosed multijunction PV cells can have 2 to 6 different bandgaps. For example, a two-layer multijunction PV cell can have (1) an active layer including at least one of boron phosphide, selenium, lanthanum copper oxide, selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), aluminum antimonide, tin sulfide, zinc phosphide, cadmium telluride, copper zinc tin sulfide (CZTS), gallium arsenide, or indium phosphide, and (2) an active layer including at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium. As another example, a three-layer multijunction PV cell may include an active layer including at least one of copper oxide (I), aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (LaCuO), an active layer including at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), aluminum antimonide, tin sulfide, zinc phosphide, cadmium telluride, or copper zinc tin sulfide (CZTS), and an active layer including at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium.As another example, a four-layer multijunction PV cell may have an active layer including at least one of: boron phosphide, lanthanum copper oxide, selenium, cadmium selenide, perovskite, or copper indium gallium diselenide (CIGS); an active layer including at least one of cadmium telluride, copper zinc tin sulfide, gallium arsenide, or indium phosphide; an active layer including at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), or silver sulfide; and an active layer including at least one of gallium antimonide, indium nitride, or germanium. As another example, a five-layer multijunction PV cell may include an active layer including at least one of copper (I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (LaCuO), an active layer including at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), or aluminum antimonide, and an active layer including at least one of gallium arsenide, indium phosphide, boron phosphide, or lanthanum copper oxide (LaCuO). and / or uranium dioxide; an active layer comprising at least one of copper sulfide, copper oxide, tin sulfide, boron arsenide, silicon, or copper zinc tin sulfur selenide (CZTSSe); and an active layer comprising at least one of copper indium selenide (CIS), zinc arsenide (Zn3As2), iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium.As another example, a six-layer multijunction PV cell may have an active layer including at least one of copper (I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (LaCuO), an active layer including at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), or aluminum antimonide, and an active layer including at least one of gallium arsenide, indium phosphide, or uranium dioxide. an active layer comprising at least one of copper sulfide, copper oxide, tin sulfide, boron arsenide, silicon, or copper zinc tin sulfur selenide (CZTSSe); an active layer comprising at least one of copper indium selenide (CIS), zinc arsenide (Zn3As2), iron disulfide, copper tin sulfide (CTS), or silver sulfide; and an active layer comprising at least one of gallium antimonide, indium nitride, or germanium. As another example, a four-layer multijunction PV cell may have an active layer including at least one of: an active layer including at least one of boron phosphide, selenium, La2CuO2, or gallium indium phosphide; an active layer including at least one of gallium arsenide, cadmium telluride, or copper zinc tin sulfide; an active layer including at least one of silicon, tin sulfide, or Zn3As2; and an active layer including at least one of germanium, indium nitride, or gallium antimonide.

[0081] In another example, a two-junction PV cell can be fabricated with active layer materials having a bandgap of 1.12 eV (Si), a bandgap of 1.43 eV (GaAs), or a bandgap of 1.5-2.3 eV (perovskites).

[0082] In another example of assembling an electrically isolated multijunction cell, the following actions are performed.

[0083] For the bottom layer, an aluminium membrane is produced and cut to size.

[0084] A P-type doped semiconductor with the lowest bandgap is deposited, then the same semiconductor with N-type doping is deposited.

[0085] A resist film is then deposited. Trenches and busbars are mechanically patterned. Trenches are etched and cleaned in the semiconductor layer. These etched structures are then filled with a liner / metal. The overburden metal is polished off. Electrical leads can be connected to the edge busbars.

[0086] A TCO layer is deposited.

[0087] For all layers above the lowest layer, the following actions can be taken:

[0088] An insulating film is deposited on the substrate. The final glass film should have a dielectric constant similar to or between the dielectric constants of the adjacent semiconductors.

[0089] Resist is spun onto the glass. Trenches (fingers) and bus bars are mechanically patterned onto the glass. These standard patterns are etched into the glass and cleaned. These etched structures are then filled with metal. The overburden metal is polished away. Electrical leads can be connected to the edge bus bars.

[0090] ·Then the TCO is deposited. A P-type doped semiconductor is deposited as the active layer and then the same semiconductor doped N-type is deposited as another part of the active layer.

[0091] A resist film is then deposited. Based on previous patterning, the film can be aligned with the trenches and busbars and mechanically patterned. Trenches are etched and cleaned in the semiconductor layer. These etched structures are then filled with a liner / metal. The overburden metal is polished off. Electrical leads can be connected to the edge busbars.

[0092] Another layer of TCO is deposited.

[0093] An anti-reflective coating (ARC) is applied on top of the TCO and the highest bandgap material.

[0094] In this example, a multijunction cell is then assembled with the lowest bandgap layer at the bottom. Subsequent layers have larger bandgaps. Alignment of the trenches between the layers is important to minimize shading of the underlying layers. These separate films are permanently bonded together to avoid moisture ingress, film delamination, and misalignment between the layers.

[0095] FIG. 8 is a chart 800 taken from Kowsar et al., "Comparative Study on Solar Cell Simulators," Int'l Conf. on Innovation in Engr,and Tech. (ICIET) 1-6, (IEEE 2019), plotting the voltage across the photodiode on the x-axis and the current density on the y-axis for three different photodiode materials. Each of the PV cells is fabricated using a different active semiconductor layer, in this example germanium, gallium arsenide, and gallium indium phosphide, which can be combined into a multijunction PV cell as described above. As shown, when exposed to light, each of the materials exhibits a different current vs. voltage relationship. Thus, to provide maximum current, each of the layers must operate at a varying voltage or maximum power point (MPP). This MPP depends on the time-varying incident radiation, cell temperature, and cell defects.

[0096] FIG. 9 is a chart 900 plotting the power output of a photovoltaic cell versus the voltage across the photodiode. As shown, the maximum power output of the cell from a particular material is achieved when the converter's voltage output is within a range of about 0.75V, as shown near the dashed area 910. When the PV cell is operated at other output voltages, the power output is reduced. For example, when the voltage output is within a range of about 0.45V, as shown in the dashed area 920, the power is about 40% less than the nominal maximum power. From this range, the output voltage of the PV cell should be increased to increase its output power. When the voltage output is within a range of about 0.9V, as shown at 930, the output voltage of the PV cell needs to be reduced to increase the output power of the PV cell. The maximum power point or range can be dynamically determined by the controller using any suitable control technique. For example, the output voltage can be adjusted toward a desired power output level using a perturb and observe method as disclosed with respect to FIG. 10. For example, when the power and voltage output indicates that the power converter is operating to the left of dashed line 940, the controller attempts to increase the voltage output of the converter. When the power and voltage output indicates that the power converter is operating to the right of dashed line 940, the controller attempts to decrease the voltage output of the converter. In this manner, the controller attempts to operate the power converter near the maximum power point region 910.

[0097] VI. Example of operating a power converter with a controller FIG. 10 is a flow chart 1000 outlining an exemplary method of operating a power converter using a controller. For example, the systems described above and below may be adapted to perform the illustrated method. In general, the controller applies a "perturb and observe" approach to regulate an isolated power converter coupled to a PV cell. The optimization goal of the method is to operate the power converter such that the PV cell is at or near its maximum power point (MPP). In some examples, the controller controls a single power converter at a time. In other examples, multiple power converters may be controlled simultaneously. For ease of explanation, the method illustrates operations performed after a single power converter is selected to be regulated.

[0098] In process block 1010, the controller measures the instantaneous voltage (V(k)) and current (I(k)) generated by the power converter. Any suitable method of measuring the voltage across the output terminals of the zone power converter and the current drawn from the output may be used. In process block 1020, the controller calculates the power P(k) as the product of the voltage and current, and calculates the difference in power ΔP between the current sample and the previous sample k−1.

[0099] If in decision block 1030 the power difference ΔP is greater than 0 (indicating an increase in power output over the previous sample), the method proceeds to decision block 1040 where the current voltage measurement is compared to the previous voltage sample(s). Referring to the example of FIG. 9, if the voltage is increasing (ΔV is greater than 0), this suggests that the converter is operating to the left of its MPP region (as an example, when the converter is operating near the dashed region 920). The controller proceeds to process block 1050 to increase the module output voltage toward the MPP by appropriately modulating the converter's control signal. For example, the module voltage of a flyback converter can be increased by increasing the portion of the duty cycle that the switch is open. On the other hand, if the voltage is decreasing (ΔV is less than 0), this suggests that the converter is operating to the right of its MPP region 910 (as an example, when the converter is operating near the dashed region 930). Therefore, the controller proceeds to process block 1060 to decrease the module output voltage by appropriately modulating the controller's control signal in process block 1060.

[0100] At decision block 1030, if the power difference ΔP is less than 0 (indicating a decrease in power from the previous sample), the method proceeds to decision block 1045 where the current voltage is compared to the previous voltage sample. Referring to the example of FIG. 9, if the voltage is decreasing, this suggests that the converter is operating to the left of its MPP (e.g., the converter is operating near the dashed region 920), then the controller proceeds to process block 1050 to increase the module voltage using a method similar to the previous paragraph. Conversely, if the voltage is increasing, the converter is operating to the right of the MPP, and the controller proceeds to process block 1060 to decrease the module voltage.

[0101] After updating the module output voltage by appropriate adjustment of the converter control signal, the method proceeds to process block 1070 where the controller updates the historical information by storing the current voltage and power for comparison. The controller then proceeds to process block 1010 where it repeats the illustrated method by again measuring voltage and current, etc.

[0102] Note that the illustrated method shows the operations performed to adjust one of the converters to output closer to its maximum power point. The controller can then proceed to perform the illustrated method for another converter in the circuit, adjusting the control signal until the maximum power point for the next converter is found.

[0103] In another example, the controller measures the voltage at each zone output and measures the output current, for example using a Hall current sensor, and the controller can simultaneously adjust the signal to each zone to continuously maintain the MPP of each zone.

[0104] VII. Exemplary Computing Environment 11 illustrates a generalized example of a suitable computing environment 1100 in which the described embodiments, techniques, and technologies may be implemented, including implementing a microcontroller for a power inverter. For example, the computing environment 1100 may be used to implement either a microcontroller or a processor, as described herein.

[0105] The computing environment 1100 is not intended to suggest any limitation as to the scope of use or functionality of the technology, as the technology may be implemented in a variety of general purpose or special purpose computing environments. For example, the disclosed technology may be implemented with other computer system configurations, including handheld devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. The disclosed technology may also be implemented in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

[0106] Referring to FIG. 11, a computing environment 1100 includes at least one central processing unit 1110 and memory 1120, 1125. In FIG. 11, this most basic configuration 1130 is included within the dashed line. The central processing unit 1110 executes computer-executable instructions and may be a real or virtual processor. The central processing unit 1110 may be a general-purpose microprocessor, a microcontroller, or other suitable processor. In a multiprocessing system, multiple processing units execute computer-executable instructions to increase processing power, and thus multiple processors may operate simultaneously. The memory 1120, 1125 may be volatile memory (e.g., registers, cache, RAM), non-volatile memory (e.g., ROM, EEPROM, flash memory, etc.), or some combination of the two. The memory 1120, 1125 stores, for example, software 1180, parameters, and other data that may implement the techniques described herein. The computing environment may have additional features. For example, computing environment 1100 includes storage 1140, one or more input devices 1150, one or more output devices 1160, and one or more communication connections 1170. Computing environment 1100 may be coupled to power inverter 100 as described in further detail above. An interconnection mechanism (not shown), such as a bus, controller, or network, interconnects the components of computing environment 1100. Typically, operating system software (not shown) provides an operating environment for other software executing in computing environment 1100 and coordinates the activities of the components of computing environment 1100.

[0107] Storage 1140 may be removable or non-removable and may include magnetic disks, magnetic tapes or cassettes, CD-ROMs, CD-RWs, DVDs, or any other medium that can be used to store information and that can be accessed within computing environment 1100. Storage 1140 stores instructions for software 1180 that can be used to implement the techniques described herein. As used herein, computer-readable storage media includes tangible media, including memory and storage devices, but does not consist of non-transitory media or signals.

[0108] The input device(s) 1150 may be a keyboard, keypad, mouse, touch screen display, touch input device such as a pen or trackball, a voice input device, a scanning device, or another device that provides input to the computing environment 1100. In the case of audio, the input device(s) 1150 may be a sound card or similar device that accepts audio input in analog or digital form, or a CD-ROM reader that provides audio samples to the computing environment 1100. The input device(s) 1150 may also include sensors and other suitable transducers for generating data regarding the PV cells or converters, such as voltage measurements, frequency measurements, current measurements, temperature, and other suitable sensor data. The output device(s) 1160 may be a display, printer, speaker, CD writer, or another device that provides output from the computing environment 1100. The output device(s) 1160 may also include interface circuitry for sending commands and signals to the generator, for example, to increase or decrease the generator's field excitation voltage or output voltage.

[0109] The communication connection(s) 1170 enable communication to another computing entity over a communication medium (e.g., a connected network). The communication medium conveys information such as computer-executable instructions, compressed graphic information, video, or other data in a conditioned data signal. The communication connection(s) 1170 include, but are not limited to, wired connections (e.g., megabit or gigabit Ethernet, InfiniBand, Fibre Channel over electrical or optical fiber connections), but also wireless technologies (e.g., Bluetooth, WiFi (IEEE 802.11a / b / n), WiMax, cellular, satellite, laser, RF over infrared connections), and other suitable communication connections for providing network connectivity to the disclosed controllers and coordinators. Both wired and wireless connections may be implemented using network adapters. In a virtual host environment, the communication connection(s) may be a virtualized network connection provided by the virtual host. In some examples, communication connection(s) 1170 are used to complement or in place of input device(s) 1150 and / or output device(s) 1160 to communicate with a DC / DC converter, a DC / AC converter, or other controlled devices.

[0110] Some embodiments of the disclosed methods may be performed in a computing cloud 1190 using computer-executable instructions implementing all or part of the disclosed techniques.

[0111] Computer-readable media are any available media that can be accessed within computing environment 1100. By way of example, and not limitation, in computing environment 1100, computer-readable media include memory 1120 and / or storage 1140. As should be readily understood, the term computer-readable storage media includes media for data storage, such as memory 1120 and storage 1140, as well as transmission media, such as conditioned data signals.

[0112] VIII. Additional Exemplary Zone Inverter Systems Including Multiple Input Transformers FIG. 12 is a simplified diagram of a photovoltaic converter system 1200 including a multi-input transformer 1202 that may be implemented in certain examples of the disclosed technology. Similar to the photovoltaic converter system 200 described above with respect to FIGS. 2A-2B, each of the converter units 1210, 1211 is coupled to a photovoltaic cell that generates an electric charge in response to incident photons received at the active layer(s) of the cell. The photovoltaic cell functions as a variable DC voltage source. The output of each of the converter units is coupled to a different respective input of a primary coil of the multi-input transformer 1202. The multi-input transformer shown in FIG. 12 has multiple windings on the primary coil. The other end of the primary coil input is coupled to a switch (e.g., switch 1270 of converter unit 1210). When the switch is closed, a circuit is completed to the other terminal of the PV cell. The dashed lines show an alternative configuration 1271 for positioning the switching between the output of the photovoltaic cell and the respective input of the converter to the transformer 1202.

[0113] Each of the flyback converter units 1210, 1211 are electrically isolated from each other. As shown, each PV cell or PV zone connects only to its respective voltage converter. When a flyback converter switch is open, the respective PV cell is not electrically connected to its transformer. A controller 1230 modulates the input signal to each of the flyback converter switches to open and close the switch. The controller synchronizes the operation of the switches to optimize the total power output of each PV cell, as described in more detail below. The multi-input transformer 1202 has a secondary coil connected to the input of a diode 1280. The output of the diode 1280 is coupled to a capacitor 1290 and to the input of the DC / AC converter 1220.

[0114] The controller 1230 also modulates the input to the DC / AC converter 1220. In this example, an H-bridge DC / AC converter with four drivers Q1 1221, Q2 1222, Q3 1223, and Q4 1224 is used, but other DC / AC converter circuits may be used as would be readily understood by one skilled in the art. For example, a cascaded H-bridge converter may provide the DC / AC converter. The DC / AC converter 1220 is configured to drive an AC load 1240 at its output.

[0115] IX. ADDITIONAL ILLUSTRATIVE ZONE INVERTER SYSTEMS INCLUDING GROUPS OF CONVERTERS FIG. 13 is a simplified diagram of a photovoltaic converter system 1300 including multiple driver groups 1301, 1302, which may be implemented in certain examples of the disclosed technology. Similar to the photovoltaic converter system 1200 described above with respect to FIG. 12, group i 1301 includes multiple converter units 1310, 1311, each coupled to a respective photovoltaic cell that generates an electric charge in response to incident photons received at the active layer(s) of the cell. The photovoltaic cell functions as a variable DC voltage source. The output of each of the converter units 1310, 1311 is coupled to a different respective input of a primary coil of a multi-input transformer 1314. The other end of each respective primary coil input is coupled to a respective switch (e.g., switch S i1 Or switch S i2 ) is connected to the synchronous switch S i1 , S i2 etc. is closed, a circuit is completed to the other terminal of the PV cell. In the alternative, the switches may be positioned between the output of the photovoltaic cell and the input of each of the converters to the multi-input transformer 1314. In an alternative configuration, each PV cell or zone is connected to a separate transformer, and the outputs of these transformers are connected in series.

[0116] Group j 1302 includes multiple converter units 1315, 1316, each coupled to a respective photovoltaic cell that generates charge in response to incident photons received at the active layer(s) of the cell. The output of each of the converter units 1315, 1316 is coupled to a different respective input of a primary coil of a multi-input transformer 1319. The photovoltaic cells coupled to each group may be selected to have similar IV characteristics (e.g., semiconductor band gap, illuminance, and / or temperature). The input switches of the converters in each respective group 1301, 1302 are synchronized together. As shown in FIG. 13, the transformer outputs of group j 1302 are connected in series with the same diodes / capacitors and loads, which are then coupled to respective DC / AC converters 1320, 1325 to deliver power to the AC load 1340. In the inverter system, the groups may be configured to deliver and convert their DC power to the AC load 1340 at a selected maximum power point. These loads may be the same load and phase as shown in Figure 13. In other examples, the output of each group is applied to the same load but different phases, or to different loads but different phases. In an alternative configuration, each PV cell or zone is connected to a separate transformer, and the outputs of these transformers are connected in series.

[0117] Each of the flyback converters in group 1301 (converter units 1310, 1311) and group 1302 (converter units 1315, 1316) are electrically isolated from each other. As shown, each PV cell or PV zone connects only to its respective voltage converter. When a flyback converter switch is open, the respective PV cell is not electrically connected to its transformer. A controller 1330 modulates the input signal to each of the flyback converter switches to open and close the switch. The controller attempts to optimize the power output of each PV group, as described in more detail below. The multi-input transformer has a secondary coil connected to the input of a diode. For group i, the output of the diode is coupled to the input of a capacitor and DC / AC converter 1320. For group j, the output of the diode is coupled to the input of a capacitor and DC / AC converter 1325.

[0118] The controller 1330 also modulates the input to the DC / AC converter 1320. In this example, a group i 1301 is used that includes an H-bridge type DC / AC converter with four drivers Q1 1321, Q2 1322, Q3 1323, and Q4 1324, but other DC / AC converter circuits may be used as would be readily understood by one skilled in the art. For example, a cascaded H-bridge may provide the DC / AC converter. The four drivers Q1 1321, Q2 1322, Q3 1323, and Q4 1324 of group i are coupled to its multi-input transformer 1314. Similarly, group j 1302 includes an additional four drivers Q1 1351, Q2 1352, Q3 1353, and Q4 1354 coupled to the output of its multi-input transformer 1319. The driver is modulated 1330 by a controller to drive an AC load 1340 .

[0119] X. Additional Examples of Disclosed Technology Additional examples of the present technology are disclosed herein as follows. In some examples, one or more computer systems may be configured to perform certain operations or actions by installing software, firmware, hardware, or combinations thereof on the system that cause the system to perform an action during operation. One or more computer programs may be configured to perform certain operations or actions by including instructions that, when executed by a data processing device, cause the device to perform an action. One general aspect includes an apparatus that may include a zone power inverter: The apparatus also includes a power inverter that may include a plurality of voltage converters, each of the plurality of voltage converters having input terminals that may include a positive input terminal and a negative input terminal, output terminals that may include a positive output terminal and a negative output terminal, a switch having a control input and a first switch terminal, the control input opening and closing the switch in response to a signal received by the control input, the first switch terminal being electrically connected to the positive output terminal or the negative output terminal, the output terminals of the voltage converters being connected in series, and each of the voltage converters being electrically isolated from each other except for the output terminals of the voltage converters being connected in series. The apparatus also includes a dc / ac converter coupled to a positive output terminal of one of the voltage converters and a negative output terminal of one of the voltage converters. The apparatus also includes a plurality of photovoltaic (PV) cells, each of the PV cells having a cathode coupled to a positive input terminal of a respective one of the voltage converters and an anode coupled to a negative input terminal of a respective one of the voltage converters. The apparatus also includes a controller coupled to a respective control input of the voltage converter switches, the controller being programmed to modulate each of the respective control inputs to regulate an output voltage at a respective output terminal of the voltage converters. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the method. Implementations may include one or more aspects according to the following clauses.

[0120] Clause 1. A zone power inverter, the power inverter comprising a plurality of voltage converters, each of the plurality of voltage converters connected to a positive input terminal (+V in ) and the negative input terminal (-V in ) with input terminal, positive output terminal (+V out ) and the negative output terminal (-V out ), a control input and a first switch terminal, the control input opening and closing the switch in response to a signal received by the control input, the first switch terminal connecting a positive output terminal (+V out ) or negative output terminal (-V out ), the output terminals of the voltage converters are connected in series, and each of the voltage converters is electrically isolated from each other except for the output terminals of the voltage converters being connected in series; out ) and the negative output terminal of one of the voltage converters (-V out ), and a plurality of photovoltaic (PV) cells, each of the PV cells being coupled to a respective one of the +V in a cathode coupled to the input terminal of each of the voltage converters, and a -V in An apparatus comprising: a plurality of photovoltaic (PV) cells having anodes coupled to input terminals; and a controller coupled to respective control inputs of voltage converter switches, the controller being programmed to modulate each of the respective control inputs to regulate output voltages at respective output terminals of the voltage converter.

[0121] Clause 2. The apparatus of clause 1, wherein at least one of the voltage converters is selected from at least one of the following types: flyback DC / DC converter, isolated CUK, isolated SEPIC (single-ended primary inductor converter), Zeta (inverted SEPIC), push-pull, forward, dual active bridge (DAB), dual half-bridge, half full-bridge, or multi-port DAB.

[0122] Clause 3. At least one voltage converter further comprises a transformer having a primary coil and a secondary coil, and a terminal of the primary coil is connected to (+V in ) terminal and a second terminal of the switch, electrically connecting the first terminal and the second terminal of the switch when the switch is closed in response to the control input.

[0123] Clause 4. A first terminal of the secondary coil is connected to the positive output terminal (+V out ), and a second terminal of the secondary coil is electrically coupled to the negative output terminal (-V out 4. The apparatus of claim 3, wherein the apparatus is electrically coupled to a

[0124] Clause 5. The method further includes a diode having an anode and a cathode, wherein a first terminal of the secondary coil is connected to the anode of the diode, and a second terminal of the secondary coil is connected to the negative output terminal (-V out 5. The apparatus of claim 4, electrically connected to a

[0125] Clause 6. The apparatus of clause 4, wherein the switch is a first switch, and the apparatus further comprises a second switch coupled to a first terminal of the secondary coil, the second switch configured to operate in anti-phase with the first switch.

[0126] Clause 7. The apparatus of clause 6, further comprising a diode connected in parallel with the second switch.

[0127] Clause 8. An apparatus as described in any one of clauses 1 to 7, wherein the DC / AC converter is an H-bridge converter controlled by the controller.

[0128] Clause 9. An apparatus as described in any one of clauses 1 to 7, wherein the controller is programmed to modulate each of the respective control inputs by modulating the duty cycle of the respective control input.

[0129] Clause 10. The apparatus of any one of clauses 1 to 7, wherein the PV cell is a region within a multi-junction electrically isolated PV cell.

[0130] Clause 11. The apparatus of clause 1, wherein the controller is programmed to measure the output voltage across the output terminals of each of the voltage converters and the current output of each of the voltage converters, and to drive, in response to the output power and output voltage of each of the voltage converters, modulate the switch control inputs of each of the voltage converters to maintain maximum output power.

[0131] Clause 12. The apparatus of clause 11, wherein the controllers are further programmed to modulate respective switch control inputs to maintain the output voltages based on a desired power output level of the respective electrical controller.

[0132] Clause 13. The apparatus of clause 11, wherein the controller is further programmed to modulate each switch control input to maintain an output power at a maximum power point of each PV cell.

[0133] Clause 14. The apparatus of clause 11, wherein the output voltage is based on a type of PV cell coupled to the voltage converter.

[0134] Clause 15. The apparatus of clause 14, wherein the switch is a microelectromechanical (MEM) switch, a depletion mode field effect transistor (FET), a depletion mode metal oxide semiconductor FET (MOSFET), an enhancement mode FET, an enhancement mode MOSFET, a mechanical switch, or a relay.

[0135] Clause 16. A method comprising: modulating, by a controller, an input signal to a plurality of voltage converters coupled in series, each of the plurality of voltage converters being electrically isolated except for the series coupling and configured to receive power from a respective photovoltaic (PV) cell of a plurality of photovoltaic cells.

[0136] Clause 17. The method of clause 16, wherein modulating the input signal includes measuring the voltage and current at the output of each voltage converter.

[0137] Clause 18. The method of clause 16, further comprising providing a plurality of voltage converters and a plurality of PV cells.

[0138] Clause 19. The method of clause 16, wherein modulating the input signal is effected using pulse width modulation (PWM).

[0139] Clause 20. The method of clause 16, wherein the controller is a proportional-integral-derivative (PID) controller, a microcontroller, or a field programmable gate array (FPGA).

[0140] Clause 21. The method of clause 16, wherein the controller is a proportional-integral (PI) controller, a microcontroller, a field programmable gate array (FPGA), or an ASIC-based controller.

[0141] Clause 22. The method of clause 16, further comprising applying a liquid or gas to the substrate of at least one of the plurality of photovoltaic cells.

[0142] Clause 23. The method of clause 16, further comprising coupling the voltage converter and the PV cell to a controller.

[0143] Clause 24. The method of clause 16, further comprising manufacturing a PV module comprising the controller and the PV cell.

[0144] Clause 25. The method of clause 16, further comprising transmitting power generated by the PV cell to a power grid using the controller and a voltage converter.

[0145] Clause 26. A computer readable storage medium storing computer readable instructions which, when executed by a computer, cause the computer to perform a method according to any one of clauses 16 to 25.

[0146] Clause 27. The computer-readable storage medium of clause 26, wherein the computer comprises a processor, a memory, and an input / output (I / O) interface to the voltage converter.

[0147] Clause 28. An insulated multijunction photovoltaic (PV) cell comprising a plurality of photosensitive semiconductor active layers, each of the active layers being electrically insulated from the other active layers and formed from a respective material having a different bandgap than the other active layers.

[0148] Clause 29. The PV cell of clause 28, wherein the active layer comprises at least one of the following: boron phosphide, selenium, lanthanum copper oxide, selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), aluminum antimonide, tin sulfide, zinc phosphide, cadmium telluride, copper zinc tin sulfide (CZTS), gallium arsenide, or indium phosphide; and an active layer comprising at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium.

[0149] Clause 30. The active layer comprises at least one of the following: copper(I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (La2CuO2), and at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), aluminum antimonide, tin sulfide, zinc phosphide, cadmium telluride, or lanthanum copper oxide (La2CuO2). 29. The PV cell of clause 28, comprising at least one of: an active layer comprising at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium.

[0150] Clause 31. The PV cell of clause 28, wherein the active layer comprises at least one of the following: an active layer comprising at least one of boron phosphide, lanthanum copper oxide, selenium, cadmium selenide, perovskite, or copper indium gallium diselenide (CIGS); an active layer comprising at least one of cadmium telluride, copper zinc tin sulfide, gallium arsenide, or indium phosphide; an active layer comprising at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), or silver sulfide; and an active layer comprising at least one of gallium antimonide, indium nitride, or germanium.

[0151] Clause 32. An active layer comprising at least one of the following: copper (I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (La2CuO2); an active layer comprising at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), or aluminum antimonide; and an active layer comprising at least one of gallium arsenide, indium phosphide, or diphosphide. 29. The PV cell of clause 28, comprising at least one of: an active layer comprising at least one of uranium oxide; an active layer comprising at least one of copper sulfide, copper oxide, tin sulfide, boron arsenide, silicon, or copper zinc tin sulfur selenide (CZTSSe); and an active layer comprising at least one of copper indium selenide (CIS), zinc arsenide (Zn3As2), iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium.

[0152] Clause 33. An active layer comprising at least one of the following: copper(I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (La2CuO2); at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), or aluminum antimonide; and at least one of gallium arsenide, indium phosphide, or uranium dioxide. 29. The PV cell of clause 28, comprising at least one of: an active layer comprising at least one of copper sulfide, copper oxide, tin sulfide, boron arsenide, silicon, or copper zinc tin sulfur selenide (CZTSSe); an active layer comprising at least one of copper indium selenide (CIS), zinc arsenide (Zn3As2), iron disulfide, copper tin sulfide (CTS), or silver sulfide; and an active layer comprising at least one of gallium antimonide, indium nitride, or germanium.

[0153] Clause 34. The PV cell of clause 28, wherein the active layer comprises at least one of the following: an active layer comprising at least one of boron phosphide, selenium, La2CuO2, or gallium indium phosphide; an active layer comprising at least one of gallium arsenide, cadmium telluride, or copper zinc tin sulfide; an active layer comprising at least one of silicon, tin sulfide, or Zn3As2; or an active layer comprising at least one of germanium, indium nitride, or gallium antimonide.

[0154] Clause 35. The PV cell of any one of clauses 29 to 34, further comprising a layer of transparent conductive oxide (TCO) disposed on a surface of at least one active layer and forming an electrical junction with a collector or emitter of the active layer.

[0155] Clause 36. The PV cell of any one of clauses 29 to 34, further comprising a first layer of transparent conductive oxide (TCO) disposed on a first surface of the at least one active layer and forming an electrical junction with an emitter of the active layer, and a second layer of TCO disposed on a second front surface of the at least one active layer and forming an electrical junction with a collector of the active layer.

[0156] Clause 37. The PV cell of any one of clauses 29 to 35, wherein at least one of the active layers is disposed on a transparent insulating substrate.

[0157] Clause 38. The PV cell of any one of clauses 29 to 35, wherein at least one of the active layers is disposed on a silicon dioxide substrate.

[0158] Clause 39. The PV cell of any one of clauses 29 to 35, further comprising a first conductor in contact with a first surface of at least one of the active layers and a second conductor in contact with a transparent conductive oxide disposed on a second front surface of at least one of the active layers, wherein at least one of the active layers is electrically connected to a conductor bus in contact with at least one of the active layers and a layer of transparent conductive oxide (TCO) disposed on the at least one active layer.

[0159] Clause 40. The apparatus of any one of clauses 1 to 15, wherein at least one of the plurality of photovoltaic cells is one of the isolated multijunction PV cells of clauses 28 to 39.

[0160] Clause 41. A zone power inverter, the power inverter comprising a plurality of voltage converters, each of the plurality of voltage converters connected to a positive input terminal (+V in ) and the negative input terminal (-V in ) with input terminal, positive output terminal +V out and the negative output terminal (-V out), a control input and a first switch terminal, the control input opening and closing the switch in response to a signal received by the control input, the first switch terminal being connected to a first output terminal having a capacitance of (-V out ) terminal of one of the voltage converters, and a switch electrically connected to the positive output terminal (+V out ) and the negative output terminal of one of the voltage converters (-V out ), and a plurality of photovoltaic (PV) cells, each of the PV cells being coupled to a respective one of the voltage converters (+V in ) input terminal of each of the voltage converters, and in 1. An apparatus comprising: a plurality of photovoltaic (PV) cells having anodes coupled to respective output terminals of a voltage converter switch; and a controller coupled to respective control inputs of a voltage converter switch, the controller being programmed to modulate each of the respective control inputs to regulate an output voltage at a respective output terminal of the voltage converter.

[0161] Clause 42. The DC / AC converter is a first DC / AC converter, the multiple-input transformer is a first multiple-input transformer, and the first DC / AC converter is coupled to a secondary output of the first multiple-input transformer; the apparatus further comprising a second DC / AC converter, the second DC / AC converter coupled to a secondary coil output of the second multi-input transformer; 41. The device according to clause 41.

[0162] Clause 43. The apparatus of clause 42, wherein the first DC / AC converter outputs to a first load and the second DC / AC converter outputs to a different second load.

[0163] Clause 44. The apparatus of clause 42, wherein the first DC / AC converter and the second DC / AC converter output to the same load.

[0164] Clause 45. The apparatus of clause 42, wherein the first DC / AC converter is configured for a different mode of operation than the second DC / AC converter with respect to at least one of an output load or an output phase.

[0165] In view of the many possible embodiments to which the principles of the disclosed subject matter may be applied, it is to be recognized that the illustrated embodiments are merely preferred examples and should not be construed as limiting the scope of the claims to those preferred examples. Rather, the scope of the claimed subject matter is defined by the following claims. Accordingly, the present invention claims everything that falls within the scope of those claims.

Claims

1. 1. An isolated multi-junction photovoltaic (PV) cell comprising a plurality of photosensitive semiconductor active layers, each of said active layers comprising: electrically isolated from other active layers, and The other active layers are formed from materials each having a different bandgap than the other active layers. Insulated multijunction photovoltaic (PV) cells.

2. The active layer is an active layer comprising at least one of the following: boron phosphide, selenium, lanthanum copper oxide, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), aluminum antimonide, tin sulfide, zinc phosphide, cadmium telluride, copper zinc tin sulfide (CZTS), gallium arsenide, or indium phosphide; an active layer comprising at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium; The PV cell of claim 1 , comprising at least one of:

3. The active layer comprises: Copper(I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (La ２ CuO ２ an active layer including at least one of an active layer comprising at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), aluminum antimonide, tin sulfide, zinc phosphide, cadmium telluride, or copper zinc tin sulfide (CZTS); an active layer comprising at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium; The PV cell of claim 1 , comprising at least one of:

4. The active layer comprises: an active layer comprising at least one of boron phosphide, lanthanum copper oxide, selenium, cadmium selenide, perovskite, or copper indium gallium diselenide (CIGS); an active layer comprising at least one of cadmium telluride, copper zinc tin sulfide, gallium arsenide, or indium phosphide; an active layer comprising at least one of tin sulfide, boron arsenide, silicon, copper zinc tin sulfur selenide (CZTSSe), copper indium selenide (CIS), zinc arsenide, iron disulfide, copper tin sulfide (CTS), or silver sulfide; an active layer comprising at least one of gallium antimonide, indium nitride, or germanium; The PV cell of claim 1 , comprising at least one of:

5. The active layer comprises: Copper(I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (La ２ CuO ２ an active layer including at least one of an active layer comprising at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), or aluminum antimonide; an active layer comprising at least one of gallium arsenide, indium phosphide, or uranium dioxide; an active layer comprising at least one of copper sulfide, copper oxide, tin sulfide, boron arsenide, silicon, or copper zinc tin sulfur selenide (CZTSSe); Copper indium selenide (CIS), zinc arsenide (Zn ３ As ２ an active layer comprising at least one of iron disulfide, copper tin sulfide (CTS), silver sulfide, gallium antimonide, indium nitride, or germanium; The PV cell of claim 1 , comprising at least one of:

6. The active layer comprises: Copper(I) oxide, aluminum arsenide, gallium indium phosphide (GaInP), zinc diphosphide, gallium selenide, selenium, boron phosphide, or lanthanum copper oxide (La ２ CuO ２ an active layer including at least one of an active layer comprising at least one of selenium, cadmium selenide, perovskite, copper indium gallium diselenide (CIGS), or aluminum antimonide; an active layer comprising at least one of gallium arsenide, indium phosphide, or uranium dioxide; an active layer comprising at least one of copper sulfide, copper oxide, tin sulfide, boron arsenide, silicon, or copper zinc tin sulfur selenide (CZTSSe); Copper indium selenide (CIS), zinc arsenide (Zn ３ As ２ an active layer comprising at least one of iron disulfide, copper tin sulfide (CTS), or silver sulfide; an active layer comprising at least one of gallium antimonide, indium nitride, or germanium; The PV cell of claim 1 , comprising at least one of:

7. The active layer comprises: Boron phosphide, selenium, La ２ CuO ２ an active layer comprising at least one of gallium indium phosphide; an active layer comprising at least one of gallium arsenide, cadmium telluride, or copper zinc tin sulfide; Silicon, tin sulfide, or Zn ３ As ２ an active layer comprising at least one of: an active layer comprising at least one of germanium, indium nitride, or gallium antimonide; The PV cell of claim 1 , comprising at least one of:

8. 8. The PV cell of claim 2, further comprising a layer of transparent conductive oxide (TCO) disposed on a surface of the at least one active layer and forming an electrical junction with a collector or emitter of the active layer.

9. a first layer of transparent conductive oxide (TCO) disposed on a first surface of the at least one active layer and forming an electrical junction with an emitter of the active layer; a second layer of TCO disposed on a second front surface of the at least one active layer and forming an electrical junction with a collector of the active layer; 8. The PV cell of claim 2, further comprising:

10. 8. The PV cell of claim 2, wherein at least one of the active layers is disposed on a transparent insulating substrate.

11. 8. The PV cell of claim 2, wherein at least one of the active layers is disposed on a silicon dioxide substrate.

12. a first conductor contacting a first surface of the at least one of the active layers; a second conductor in contact with the transparent conductive oxide disposed on the second front surface of the at least one of the active layers; the at least one of the active layers is electrically connected to a conductor bus in contact with the at least one of the active layers and a layer of transparent conductive oxide (TCO) disposed over the at least one active layer; 8. A PV cell according to any one of claims 2 to 7.

13. 1. A zone power inverter comprising: The power inverter comprises a plurality of voltage converters, each of the plurality of voltage converters comprising: Positive input terminal (+V ｉｎ ) and the negative input terminal (-V ｉｎ ) an input terminal having Positive output terminal (+V ｏｕｔ ) and negative output terminal (-V ｏｕｔ ) an output terminal having A switch having a control input and a first switch terminal, the control input opening and closing the switch in response to a signal received by the control input, the first switch terminal being connected to the negative output terminal (-V ｏｕｔ a switch electrically connected to the the output terminals of the voltage converters are coupled to respective inputs of a multi-input transformer, each of the voltage converters being electrically isolated from one another except for their output terminals being coupled to respective windings of the primary cores of the transformers; Zone power inverter, The positive output terminal of one of the voltage converters (+V ｏｕｔ ) and the negative output terminal of one of the voltage converters (−V ｏｕｔ a DC / AC converter coupled to the a plurality of photovoltaic (PV) cells, each of the PV cells being connected to a respective one of the (+V ｉｎ ) input terminal of each of the voltage converters, and ｉｎ ) a plurality of photovoltaic (PV) cells having anodes coupled to an input terminal; and a controller coupled to the respective control inputs of the voltage converter switches, the controller being programmed to modulate each of the respective control inputs to regulate an output voltage at the respective output terminal of the voltage converter; An apparatus comprising:

14. the DC / AC converter is a first DC / AC converter, the multi-input transformer is a first multi-input transformer, and the first DC / AC converter is coupled to a secondary output of the first multi-input transformer; The device, further comprising a second DC / AC converter, the second DC / AC converter coupled to a secondary coil output of the second multi-input transformer; 14. The apparatus of claim 13.

15. 15. The apparatus of claim 14, wherein the first DC / AC converter outputs to a first load and the second DC / AC converter outputs to a different second load.

16. 15. The apparatus of claim 14, wherein the first DC / AC converter and the second DC / AC converter output to the same load.

17. 15. The apparatus of claim 14, wherein the first DC / AC converter is configured for a different mode of operation with respect to at least one of an output load or an output phase than the second DC / AC converter.

18. modulating, by a controller, input signals to a plurality of voltage converters having output terminals coupled to respective inputs of a multi-input transformer, each of the plurality of voltage converters being electrically isolated from one another except that its output terminals are coupled to respective windings of a primary core of the transformer, and each of the plurality of voltage converters being configured to receive power from a respective photovoltaic (PV) cell of a plurality of photovoltaic cells; method.

19. 20. The method of claim 18, wherein modulating the input signal comprises measuring the voltage and current at the output of the respective voltage converter.

20. The method of claim 18 , further comprising providing the plurality of voltage converters and the plurality of PV cells.

21. 20. The method of claim 18, wherein modulating the input signal is effected using pulse width modulation (PWM).

22. 20. The method of claim 18, wherein the controller is a proportional-integral-derivative (PID) controller, a microcontroller, or a field programmable gate array (FPGA).

23. 20. The method of claim 18, wherein the controller is a proportional-integral (PI) controller, a microcontroller, a field programmable gate array (FPGA), or an ASIC-based controller.

24. 20. The method of claim 18, further comprising applying a liquid or gas to a substrate of at least one of the plurality of photovoltaic cells.

25. further comprising coupling the voltage converter and the PV cell to the controller.

20. The method of claim 18.

26. manufacturing a PV module comprising the controller and the PV cell.

20. The method of claim 18.

27. and transmitting power generated by the PV cell to a power grid using the controller and the voltage converter.

20. The method of claim 18.

28. 28. A computer readable storage medium storing computer readable instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 18 to 27.

29. The computer a processor; Memory and an input / output (I / O) interface to at least one of the plurality of voltage converters; 30. The computer-readable storage medium of claim 28, comprising:

30. 1. A zone power inverter comprising: The power inverter comprises a plurality of voltage converters, each of the plurality of voltage converters comprising: Positive input terminal (+V ｉｎ ) and the negative input terminal (-V ｉｎ ) an input terminal having Positive output terminal (+V ｏｕｔ ) and negative output terminal (-V ｏｕｔ ) an output terminal having A switch having a control input and a first switch terminal, the control input opening and closing the switch in response to a signal received by the control input, the first switch terminal being connected to the positive output terminal (+V ｏｕｔ ) or the negative output terminal (-V ｏｕｔ a switch electrically connected to the Zone power inverter, The positive output terminal of one of the voltage converters (+V ｏｕｔ ) and the negative output terminal of one of the voltage converters (−V ｏｕｔ a DC / AC converter coupled to the a plurality of photovoltaic (PV) cells, each of the PV cells being connected to the +V ｉｎ a cathode coupled to the input terminal of each one of the voltage converters, and ｉｎ a plurality of photovoltaic (PV) cells having anodes coupled to an input terminal; a controller coupled to the respective control inputs of the voltage converter switches, the controller being programmed to modulate each of the respective control inputs to regulate an output voltage at the respective output terminal of the voltage converter; An apparatus comprising:

31. 31. The apparatus of claim 30, wherein at least one of the voltage converters is selected from at least one of the following types: flyback DC / DC converter, isolated CUK, isolated SEPIC (single-ended primary inductor converter), Zeta (inverted SEPIC), push-pull, forward, dual active bridge (DAB), dual half-bridge, half full-bridge, or multi-port DAB.

32. At least one voltage converter The transformer further includes a primary coil and a secondary coil, the terminal of the primary coil being connected to the positive input terminal (+V ｉｎ 32. The apparatus of claim 31 , wherein a first terminal of the switch is coupled to the first terminal of the switch and a second terminal of the switch when the switch is closed in response to the control input, electrically connecting the first terminal and the second terminal thereof.

33. A first terminal of the secondary coil is connected to the positive output terminal (+V ｏｕｔ ) of the at least one voltage converter, and a second terminal of the secondary coil is electrically coupled to the negative output terminal (-V ｏｕｔ 33. The apparatus of claim 32, wherein the first and second electrodes are electrically coupled to a first electrode.

34. The at least one voltage converter further includes a diode having an anode and a cathode, the first terminal of the secondary coil being connected to the anode of the diode and the second terminal of the secondary coil being connected to the negative output terminal (-V ｏｕｔ 34. The device of claim 33, wherein the device is electrically connected to a

35. 35. The apparatus of claim 34, wherein the switch is a first switch, and the apparatus further comprises a second switch coupled to the first terminal of the secondary coil, the second switch configured to operate in anti-phase with the first switch.

36. 36. The apparatus of claim 35, further comprising a diode connected in parallel with the second switch.

37. 37. The apparatus of any one of claims 30 to 36, wherein the DC / AC converter is an H-bridge converter controlled by the controller.

38. 37. Apparatus according to any one of claims 30 to 36, wherein the controller is programmed to modulate each of the respective control inputs by modulating the duty cycle of the respective control input.

39. 37. The apparatus of any one of claims 30 to 36, wherein the PV cell is a region within a multi-junction electrically isolated PV cell.

40. The controller: programmed to measure an output voltage across the output terminals of each of the voltage converters and a current output of each of the voltage converters, and to modulate and drive a switch control input of each of the voltage converters in response to the output power and the output voltage of each voltage converter to maintain maximum output power; 31. The apparatus of claim 30.

41. 41. The apparatus of claim 40, wherein the controllers are further programmed to modulate the respective switch control inputs to maintain the output voltages based on a desired power output level of the respective electrical controllers.

42. 41. The apparatus of claim 40, wherein the controller is further programmed to modulate the respective switch control input to maintain the output power at a maximum power point of the respective PV cell.

43. 41. The apparatus of claim 40, wherein the output voltage is based on the type of PV cell coupled to the voltage converter.

44. 31. The apparatus of claim 30, wherein the switch is a microelectromechanical (MEM) switch, a depletion-mode field effect transistor (FET), a depletion-mode metal-oxide-semiconductor FET (MOSFET), an enhancement-mode FET, an enhancement-mode MOSFET, a mechanical switch, or a relay.

45. the output terminals of the voltage converters are connected in series, and each of the voltage converters is electrically isolated from each other except for the fact that their output terminals are connected in series; 31. The apparatus of claim 30.

46. 46. ​​The apparatus of any one of claims 13 to 17, claims 30 to 36, or claims 40 to 45, wherein at least one of the plurality of photovoltaic cells is one of the insulated multijunction PV cells of claims 1 to 7.

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