Space solar power generation system

Abstract

Implementations of the disclosed subject matter provide a system having an artificial light source disposed at a distance from the Earth or other celestial body, the artificial light source being configured to project one or more light beams onto the Earth or other celestial body. The system can include a photovoltaic array disposed over an area on the Earth or other celestial body that is 200 m to 20 km or more in any one dimension, the photovoltaic array being configured to receive one or more of the projected light beams and to convert the received one or more light beams into electricity.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the priority of U.S. Application No. 63 / 368,534, filed on July 15, 2022, the disclosure of which is incorporated herein by reference in its entirety.

Background Art

[0002] Space - based solar power (SSP) systems include microwave - based systems and optical systems. Microwave - based systems typically require a large aperture deployed in space, along with a large rectenna aperture on the ground. Such systems typically have safety issues based on acceptable microwave exposure limits. Optical SSP systems have attempted to address the problems of microwave - based SSP systems. Previously proposed optical SSP systems have potentially higher safety intensity limits than microwave - based SSP systems. However, such previously proposed optical SSP systems typically use a small Earth aperture that requires a high - beam - quality laser source and use a ground - based solar cell array made of materials different from most solar cells used for large - scale terrestrial power generation.

Summary of the Invention

[0003] Implementations of the disclosed subject matter can provide a system having an artificial light source disposed at a distance from Earth or another celestial body, the artificial light source being configured to project one or more light beams onto Earth or another celestial body. The system can include a photovoltaic array disposed in an area on Earth or another celestial body that is 200 m - 20 km or more in any one dimension, the photovoltaic array being configured to receive the one or more projected light beams and to convert the received one or more light beams into electricity.

[0004] Implementations of the disclosed subject matter can provide a system having at least one satellite that includes an artificial light source configured to project light onto the Earth or other celestial body and a photovoltaic array configured to power the artificial light source. In such a system, a direct electrical connection can exist between one or more cells of the photovoltaic array and the unregulated artificial light source. At least a portion of the photovoltaic array can be impedance matched to the effective load impedance of the artificial light source.

[0005] Implementations of the disclosed subject matter can provide a system having at least one satellite that includes an artificial light source configured to project one or more light beams onto the Earth or other celestial body, a photovoltaic array electrically coupled to the artificial light source and configured to power the artificial light source, and a radiator panel thermally coupled to the artificial light source and configured to dissipate heat generated by the artificial light source when projecting the one or more light beams. The system can include a terrestrial photovoltaic array that is sized to be greater than or equal to 200 m - 20 km in any one dimension and is disposed in an area on the Earth or other celestial body and configured to receive the one or more projected light beams and convert the received one or more light beams into electricity.

[0006] Further features, advantages, and implementations of the disclosed subject matter may be set forth or apparent from consideration of the following detailed description, drawings, and claims. It is to be understood that both the foregoing summary and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the claims.

Brief Description of the Drawings

[0007] The accompanying drawings, which are included to provide a further understanding of the disclosed subject matter, are incorporated in and constitute a part of this specification. The drawings also illustrate implementations of the disclosed subject matter and, together with the detailed description, serve to explain the principles of the implementations of the disclosed subject matter. No attempt is made to show structural details in more detail than may be necessary for a fundamental understanding of the disclosed subject matter and the various ways in which it may be implemented.

Figure 1

Figure 2A

Figure 2B

Figure 3

Best Mode for Carrying Out the Invention

[0008] The implementations disclosed herein relate to systems, devices, and technologies for providing space solar power (SSP). Conventional attempts to design or build SSP systems typically fall into two categories: microwave-based systems and optical / infrared systems. Microwave systems have received the most attention due to their perceived lower technical requirements. For example, there have been numerous laboratory demonstrations of microwave amplifiers at nearly the required efficiency and power density (typically at least 70% and over 1000 W / kg), and rectenna electronics at the required efficiency (typically at least 70%). Based on these experiments and real-world terrestrial experiments that transmit multiple kW of power over distances of multiple kilometers (km), microwave-based SSP has conventionally been considered more mature. However, the field has been hampered by a variety of other limitations, including the requirement for large apertures (several km in diameter) expanded greatly in space that require assembly in space, large rectenna apertures on the ground, safety and / or scale issues driven by low allowable microwave exposure limits (typically tens of W / m 2 2 or less). Microwave-based solutions also suffer from problems common to all conventional SSP approaches, including launch costs, assembly costs and difficulties in space, and electronics costs.

[0009] Some optical SSP approaches have attempted to address these problems. The shorter wavelengths used by these technologies allow for smaller apertures in space, less than 1 m, compared to the several-kilometer scales required for microwave-based approaches, which enables the system to be a constellation of satellites that can be launched, deployed, and operated independently. Such satellites are small enough to eliminate the need for assembly of large structures in space. Optical (especially near-infrared (IR)) lasers potentially have even higher safety intensity limits, but they are still limited to less than about 1 kW / m 2 2 (for long-term exposure), limiting the usefulness of small Earth apertures allowed by good beam quality laser sources. That is, about 1 kW / m2 Such safety intensity limits that are below are for a laser source acting as a point source, such as those used in conventional optical SSP approaches. In contrast, the laser source used in implementations of the disclosed subject matter can be an extended source (e.g., a visually extended source) whose intensity (power per unit area) can safely exceed about 1 kW / m 2 The artificial light source used in implementations of the disclosed subject matter can be extended over a larger area of space (e.g., by multiple satellites), which can safely provide light without damaging the eyes of humans or animals. The beam quality of such conventional optical SSP approaches can be based on beam parameter product (BPP) values, beam divergence, etc. A low value of BPP means high beam quality.

[0010] Conventional optical SSP systems have proposed using diode pumped solid state lasers (DPSSLs) or other diode pumped lasers (e.g., diode pumped alkali lasers) to provide both high total power and relatively good beam quality, using, for example, arrays that are coherently or incoherently combined. These systems provide moderately high efficiency and good beam quality, but their wavelengths (typically greater than 1 μm for DPSSLs) require the use of expensive photovoltaic receiver cells, such as those with III-V material-based cells. Thus, in these past proposals, terrestrial efficiency and economic considerations tend to drive optical solutions towards small receiver areas. These small areas reduce the cost of the receiver array but require high (unsafe) intensities to obtain moderately large amounts of power and extremely accurate pointing and tracking to ensure that the delivered beam stays on the small receiver. The lower efficiency, expensive receivers, need for accurate pointing, and high intensity requirements of DPSSLs have led to conventional optical SSP technologies being unacceptable both technically and economically.

[0011] Conventional systems have tried to utilize lasers of relatively short wavelengths to enable small spot sizes on Earth with small apertures in space. Such a configuration would be advantageous as it could minimize the cost of the ground-based receivers and the space-based telescopes. However, in order to obtain large amounts of power, such systems face an inevitable trade-off: either dramatically exceeding safe intensities on the ground or using much larger receivers on the ground. To date, neither option has been feasible. As realized in the implementation of the disclosed subject matter discussed throughout, if maintaining safe intensities is chosen, the resulting minimum receiver size for large-scale economically interesting power levels becomes large enough that the transmission aperture in space becomes very small, or more importantly, spatial coherence (effectively, laser beam quality) becomes less important.

[0012] Typically, these conventional systems rely on diode-pumped fiber lasers or diode-pumped bulk lasers, which convert the efficient but spatially incoherent light emitted by a large array of laser diodes (whether fiber-coupled or not) into a much smaller number of highly coherent beams for projection onto the Earth. The use of this pumping unfortunately typically results in a laser wavelength greater than 1 μm, which means that the solar cell receiver array has to use relatively new types of materials and cannot use the photovoltaic arrays in existing solar power plants (solar farms). Specifically, such receivers generally cannot be based on silicon, copper indium gallium selenide (CIGS), cadmium telluride (CdTe), and / or perovskite, or other common low-cost receiver materials and architectures. Other conventional diode-pumped systems (e.g., diode-pumped alkali laser (DPAL) systems) use shorter wavelengths but have efficiency losses and cost and complexity issues similar to those of the aforementioned diode-pumped systems and / or diode-pumped solid-state systems.

[0013] Implementations of the disclosed subject matter may use fiber-coupled diode laser arrays since the importance of spatial coherence decreases when using a sufficiently large terrestrial receiver. This configuration may increase electro-optical efficiency by avoiding intermediate optical-optical lasing conversion and may reduce system mass. Implementations of the disclosed subject matter can use larger receiver apertures of terrestrial photovoltaic arrays that may be provided by equivalently sized solar power plants and receivers. Implementations of the disclosed subject matter can use artificial light sources in space that output beams with low coherence, such as, for example, by using directly fiber-coupled, incoherently combined diode lasers. The disclosed subject matter may improve system efficiency, thereby reducing thermal requirements and enabling operation at lower temperatures. The ability to operate at lower temperatures can further increase the efficiency of artificial light sources (e.g., laser efficiency). Implementations of the disclosed subject matter can shift the wavelength of the artificial light source to regions that can easily pass through the atmosphere and can be efficiently converted by conventional solar arrays.

[0014] FIG. 1 shows a schematic representation of a space solar power generation system 10 according to an implementation of the disclosed subject matter. One or more photovoltaic (PV) arrays 110 can be deployed in orbit as part of a satellite 200. The PV arrays 110 can collect solar energy, convert the collected solar energy into electrical energy, store the energy, and / or transmit the energy to a receiver 130 on Earth or on another celestial body. The satellite 200 can include an artificial light source (e.g., a diode laser 120) that can be powered by the electrical energy from the PV arrays 110. The diode laser 120 can be coupled to the PV arrays 110 and used to transmit the received and / or stored power to a terrestrial photovoltaic array (e.g., the receiver 130) via one or more beams 300. In some implementations, the diode laser 120 can be directly coupled to the PV arrays 110, as described in detail below. The receiver 130 can be configured to be sized to accept a broad or incoherent beam pattern from the diode laser 120. The receiver 130 can use conventional PV arrays common in modern solar power plants. The wavelength of one or more beams 300 output from the laser diode 120 can be selected to match the most efficient absorption wavelength(s) of the receiver 130, as disclosed in more detail below. The receiver 130 can convert the laser light received from one or more beams 300 into electricity for use and / or storage via, for example, a conventional power grid 140, a battery-based or similar storage system 150, or the like. Although FIG. 1 shows one satellite 200, there can be multiple satellites 200 that can output beams 300 to one or more receivers 130.

[0015] The efficiency of the diode laser 120 can have an inverse correlation with the junction temperature. In laboratory tests, a laser diode with a room temperature efficiency of 60 - 65% can approach an efficiency of 75 - 85% when cooled to temperatures below 0°C. Some laboratory tests produce a diode efficiency of 85% at -40°C, while others establish an efficiency of >70% at approximately 0°C.

[0016] This inverse correlation between efficiency and temperature has little impact on typical laser diode systems because the energy cost of refrigerating and / or cooling the laser diode is greater than the energy savings due to the increased efficiency. However, this inverse correlation between efficiency and temperature becomes important when operating a laser diode in space applications such as those disclosed herein. In space, the background temperature can be extremely low when appropriately dealing with the heat input from the sun, the earth, and / or other celestial bodies. These heat inputs to the SSP according to the disclosed subject matter can be addressed through shielding, blocking, and / or coatings or materials with high emissivity / low absorptivity. Thus, virtually any low temperature in space can be limited only by solar exposure, materials, and the heat flux per unit area. For example, materials can be selected to achieve an economically low enough mass. That is, if a low-cost and highly conductive material is selected, there will be more radiator panels per unit of waste heat, enabling the diode laser 120 to operate at a lower temperature. The lighter the radiator panel (e.g., the higher the conductivity per unit mass of the fins), the lower the temperature the laser (e.g., the diode laser 120) can reach. This can reduce both the power required and the size of the PV array (e.g., the PV array 110).

[0017] Therefore, when using diode lasers in space, especially for power beam applications, this temperature-dependent efficiency effect can be utilized with low mass, cryogenic radiators, and state-of-the-art low-absorption and / or high-emissivity coatings to achieve efficiencies substantially higher than those of normal laser diodes. This effect is generally known for terrestrial laser applications but has not been applied to space applications until now, and in particular, not to space power beam applications using diode lasers.

[0018] Near-infrared (NIR) lasers can have high efficiency and can use existing solar cell technology as a receiver, so they can be used for power beam applications. In typical existing mass-produced solar cell technologies, including III-V cells (such as gallium arsenide (GaAs) cells), cadmium telluride (CdTe) cells, copper indium gallium selenide (CIGS) cells, and silicon cells, the NIR wavelength can maximize the conversion efficiency. This is because the photon energy is close to, but not lower than, the bandgap energy of these materials. This effect can improve and / or maximize the quantum efficiency (the ratio of generated electrons to absorbed photons), and since the energy of photons greater than the bandgap energy is wasted as heat, it can also improve and / or maximize the power efficiency.

[0019] By selecting an artificial light source (e.g., a laser) that efficiently generates wavelengths close to the bandgap of the materials of a conventional solar array, the overall system efficiency can be increased and / or maximized. The receiver technology of the disclosed subject matter uses existing mass-produced large-area solar cells / modules / farms, thus reducing and / or eliminating the need for a narrow beam to reduce system cost. There are two advantages to this combination. Diode-pumped lasers have better beam quality than direct diode lasers, but their longer wavelengths require new types of receiver cell technologies (e.g., solar arrays made from materials different from conventional ones), and their overall transmission efficiency is lower. Thus, the implementations disclosed herein can use diode lasers as the artificial light source without using an intermediate stage for pumping different materials.

[0020] The implementations of the disclosed subject matter can directly utilize diode lasers by incoherently coupling light from multiple diodes to an optical fiber. The beams from the laser and the optical fiber can be combined and then directed, or simply directed through an optical system to a ground-based receiver. This configuration can enable improvements in beamed solar power, as will be described later in connection with FIGS. 2A-2B.

[0021] Laser diodes typically require driver electronics to prevent overcurrent damage. This is because, being diode devices, their current-voltage curves appear as effectively flat sections with little slope up to the threshold voltage / current, at which point the slope of the current / voltage curve rises dramatically. As shown in Figure 3, the current-voltage curve of a diode laser has a low slope (i.e., is effectively flat) up to the threshold point (e.g., the point at 0.8 arbitrary voltage units shown in Figure 3), at which point the current / voltage curve rises with an increased slope. This slope depends on the temperature of the device, manufacturing variations, device age, and other factors. Due to the steepness of this curve, a current-regulated power supply with a low source impedance can be used, but such power supplies are typically complex, heavy, and / or expensive and reduce overall efficiency.

[0022] Similarly, the current-voltage curve of a solar cell is typically a nearly flat section (i.e., a constant current as the voltage increases starting from the short-circuit current) up to a specific point where the current drops rapidly to zero when the voltage reaches the open-circuit voltage of the cell. As shown in Figure 3, the current-voltage curve of a solar cell can be nearly flat up to the threshold point (e.g., the point at 0.85 arbitrary voltage units shown in Figure 3), at which point the voltage / current has a significant decrease (i.e., the negative slope gradually increases to zero). In normal operation, a maximum power-point tracker (MPPT) circuit is used to adjust the effective load impedance to operate the power supply at the bend in the solar cell curve (e.g., starting at the point at approximately 0.85 arbitrary voltage units as shown in Figure 3) to extract maximum power.

[0023] In both the case of a laser and the case of a solar cell, power electronics typically takes the form of a high-frequency switching DC-DC converter and sometimes includes a smoothing stage and / or a linear stage to provide precise current control or current limiting. When operating a solar cell and a diode laser effectively constant for beamed space solar power, implementations of the disclosed subject matter can eliminate both sets of power electronics (i.e., power electronics for the laser and power electronics for the solar cell).

[0024] By matching the number of series-parallel arrangements of a solar cell and a laser diode, implementations of the disclosed subject matter can match the current-voltage (I-V) curves of the two devices. That is, when the I-V curves of the solar cell and the diode laser are properly matched, the nearly constant current output of the solar cell can provide a current limit for safe laser diode operation and can extract the maximum possible power from the solar cell using the threshold voltage of the laser diode and / or diode-like impedance behavior.

[0025] Implementations disclosed herein can operate without the intervention of power electronics conventionally required for stability by matching the I-V curves of the two devices and by matching the number of series-parallel arrangements of the solar cell and the laser diode as described above. That is, by using this matching, implementations of the disclosed subject matter do not use conventional high-bandwidth electronics (e.g., conventional power electronics). In some implementations, very low-bandwidth shunt and / or fixed shunt (e.g., bypass) current control can be used to accommodate device manufacturing variations and / or to accommodate the start of designed overcurrent operation, and thus can address aging degradation. The use of this low-bandwidth or fixed shunt (bypass) may be used not for stability or safety, but to maximize output power over time. That is, a conservative fixed-setpoint that can be stable over time but output slightly less power may be used.

[0026] Figures 2A-2B illustrate examples of the SSP satellite 200 and the ground receiver 130 of FIG. 1, in accordance with implementations of the disclosed subject matter. The satellite 200 may have a plurality of modules 202 that may include one or more PV arrays 110, one or more laser diode modules 120, one or more radiator panels 210, and / or one or more output fibers 215. The one or more PV arrays 110 can convert sunlight into electrical power. The one or more laser diode modules 120 can convert electrical power into optical power and deliver the optical power to a fiber. For example, as shown in FIG. 2A, the output of the one or more laser diode modules 120 can be provided to the output fiber 215, and one or more of the output fibers 215 can be combined using a fiber combiner 220 to form one or more delivery fibers 230. Alternatively, the output from the one or more laser diode modules 120 may be provided directly to a delivery telescope 240 for transmission to one or more receivers 130 on Earth and / or other celestial bodies. In another example, FIG. 2B shows that the output of the one or more laser diode modules 120 can be provided to a delivery fiber 216, and the beams from the delivery fiber can be combined by a free-space beam combiner 217 and provided to the delivery telescope 240.

[0027] As shown in FIGS. 2A-2B, one or more radiator panels 210 can be used to remove waste heat from the laser diode module 120. One or more delivery telescopes 240 can project the optical power generated by the laser diode module 120 in a divergent manner that can be made to coincide with one or more ground receivers 130. The laser diode module 120 and the receiver 130 can be IV curve matched to improve power transmission efficiency. Before transferring power to one or more delivery telescopes 240 for transmission to one or more ground receivers 30, as shown in FIG. 2A, a fiber combiner 220 can be used to couple one or more of the output fibers 215 from the laser module 120 into a smaller number of delivery fibers 230. As shown in FIG. 2B, a free space beam combiner 217 can combine the beams received from the delivery fibers 216 and provide the combined beam to one or more delivery telescopes 240 for transmission to one or more ground receivers 30. As shown in FIGS. 2A-2B, a coarse alignment mirror 250 can be used to redirect the output beam 300 of the delivery telescope 240 towards the Earth and / or other celestial bodies, providing coarse alignment to one or more receivers 130 that can be part of a solar power plant on the ground and / or other celestial bodies for those beams.

[0028] As described above, the implementations disclosed herein benefit from developments and insights that were not available or fully exploited in conventional SSP systems. The receiving terrestrial arrays used in implementations of the disclosed subject matter need not be very small and can be on the order of the size of modern solar power plants. Using a large receiving spot size (e.g., the area of the receiver of a solar power plant) can allow the energy involved to be notably safer compared to conventional approaches. A large receiving spot size can enable a relatively inexpensive but efficient incoherently combined diode laser array to transmit orbital power to a terrestrial receiver. The artificial light sources used in implementations of the disclosed subject matter can extend over a larger area of space (e.g., with multiple satellites), which can safely provide light to a large receiving spot size (e.g., a terrestrial receiver) without damaging the eyes of humans or animals. In some implementations, existing solar power plants can be used since highly efficient NIR wavelength lasers, as described throughout in relation to the disclosed implementations, can be used. Illuminating an existing solar power plant at a wavelength that matches the wavelength at which a conventional solar cell can efficiently receive and convert light into electricity can result in an efficiency increase that was not achievable in conventional systems. Operating laser diodes using orbital solar panels can be current self-limiting and can eliminate most power electronics requirements, further reducing system complexity and cost without sacrificing efficiency.

[0029] As shown in FIGS. 1-3, an implementation of the disclosed subject matter can provide a system (e.g., system 10 shown in FIG. 1) having an artificial light source (e.g., diode laser 120 shown in FIGS. 1-2B) disposed at a distance from the Earth or other celestial body, and the artificial light source is configured to project one or more light beams (e.g., beam 300 shown in FIG. 1) onto the Earth or other celestial body. The system is disposed in an area on the Earth or other celestial body that is 200 m - 20 km or more in any one dimension and / or in diameter, and is configured to receive the one or more projected light beams, and can include a terrestrial photovoltaic array (e.g., receiver 130 shown in FIGS. 1-2B) configured to convert the received one or more light beams into electricity. For example, the terrestrial photovoltaic array (e.g., receiver 130 shown in FIGS. 1-2B) can be disposed in an area that is greater than 20 km in any one dimension, such as, for example, 21 - 30 km, 31 - 50 km, 51 - 70 km, 71 - 100 km, or more in any one dimension.

[0030] The artificial light source can be the diode laser 120 shown in FIGS. 1-2B. The peak wavelength range of the one or more light beams of the artificial light source can be 750 nm - 2000 nm. For example, the artificial light source for the system can have a peak wavelength range of 800 - 1020 nm. In another example, the artificial light source for the system may have a peak wavelength range of 780 - 850 nm. In yet another example, the artificial light source for the system may have a peak wavelength range of 940 - 1020 nm. Examples of the peak wavelength range of the artificial light source can have wavelengths of 808 nm, 915 nm, and / or 976 nm. In some implementations, the minimum beam parameter product (BPP) of the artificial light source can be greater than 10 mm - mrad. The BPP can be the product of the beam radius (measured at the beam waist) and the beam divergence half-angle. In some implementations, the artificial light source can have a range of 10 - 100 mm - mrad.

[0031] The artificial light source can be selected based on the efficiency range of the terrestrial photovoltaic array, along with the peak wavelength range. The terrestrial photovoltaic array can be the terrestrial receiver 130 shown in FIGS. 1-2B. For example, the terrestrial photovoltaic array can be formed from silicon, gallium arsenide (GaAs), indium gallium arsenide (InGaAs), aluminum gallium arsenide (AlGaAs), copper indium gallium selenide (CIGS), cadmium telluride (CdTe), perovskite, and / or other materials suitable for converting light into electricity. Based on the efficiency of the one or more materials forming the terrestrial photovoltaic array, an artificial light source having a peak wavelength range that matches the efficiency of the one or more materials of the terrestrial photovoltaic array can be selected. That is, the bandgap of the material forming the terrestrial photovoltaic array can be matched to the range of wavelengths of light configured to be output by the artificial light source, such that the bandgap of the material of the terrestrial photovoltaic array is not longer than the wavelength corresponding to the bandgap of the material of the terrestrial photovoltaic array, as detailed above.

[0032] The artificial light source can be a plurality of lasers such as laser diodes, fiber lasers, diode-pumped solid lasers and the like. In some implementations, the lasers of the artificial light source can be multimode and can have lower coherence than single-mode lasers. Coherent light has photons that oscillate at the same frequency and has wavelengths that are in phase. In contrast, the photons of incoherent light oscillate at different frequencies and their wavelengths are not in phase with each other. The beam of an artificial light source having a multimode laser can be said to be less coherent, for example, than the coherent beam from a single-mode laser.

[0033] In some implementations, the artificial light source can include a plurality of modules, each module including a plurality of laser diodes coupled to a delivery fiber. For example, the module can be the laser diode module 120 shown in FIGS. 2A-2B. One or more modules (e.g., the laser module 120 shown in FIGS. 2A-2B) can be configured to operate at a temperature of 210K - 315K.

[0034] Delivery fiber 215 can be coupled to laser diode module 120. One or more of the delivery fibers 215 from a plurality of modules 120 can be combined into a free-space beam that forms one or more optical beams (e.g., beam 300 shown in FIGS. 2A-2B) projected from the system. For example, as shown in FIG. 2A, the output fiber 215 from laser diode module 120 can be combined by fiber combiner 220 that can be coupled to delivery fiber 230. In another example, as shown in FIG. 2B, delivery fiber 216 from laser diode module 120 may have an output beam that can be combined in free space by free-space beam combiner 217. Beam combining configurations other than those shown in FIGS. 2A-2B may be used, such as polarization beam combining, further spatial combining, or spectral beam combining in one or more steps using gratings, dichroic mirrors, and / or other frequency-selective elements.

[0035] Light from a plurality of light sources can be combined coherently or incoherently. When the combination of light is coherent, the combined light can have photons that oscillate at the same frequency and have waveforms in the same phase. When the light is combined incoherently, the combined light can have photons that oscillate at different frequencies and have waveforms that are out of phase with each other.

[0036] In FIG. 2A, delivery fiber 230 can be coupled to a plurality of delivery telescopes 240. In FIG. 2B, the output of free-space beam combiner 217 can be provided to delivery telescope 240. In FIGS. 2A-2B, the beam output from delivery telescope 240 can be reflected by mirror 250 to form output beam 300. In some implementations, an optical beam projected by an artificial light source can have reduced coherence when a multimode diode laser is used as the artificial light source.

[0037] The output beam can be directed towards a terrestrial photovoltaic array (e.g., receiver 130) disposed in an area on the Earth or on another celestial body. In some implementations, the terrestrial photovoltaic array can be part of a solar power plant capable of receiving one or more of the output beams 300.

[0038] As shown in FIGS. 1-2B, the system can include a satellite having an artificial light source (e.g., diode laser 120), a photovoltaic array (e.g., PV array 110) electrically coupled to the artificial light source and configured to supply power to the artificial light source, and at least one radiator panel (e.g., radiator panel 210). The satellite's photovoltaic array can be formed from silicon, gallium arsenide (GaAs), indium gallium arsenide (InGaAs), aluminum gallium arsenide (AlGaAs), copper indium gallium selenide (CIGS), cadmium telluride (CdTe), perovskite, and / or other suitable materials, or combinations of these materials in a multi-junction cell, and can convert light into electricity.

[0039] The size of the satellite can be less than 1000 m, less than 1200 m, less than 1500 m, less than 1800 m, less than 2000 m, and / or any other suitable distance in any direction. The artificial light source can be thermally coupled to at least one radiator panel, and the radiator panel dissipates heat from the artificial light source when the artificial light source is operating. That is, the at least one radiator panel can be configured to dissipate heat generated by the artificial light source into outer space. In some implementations, one or more of the above modules can be distributed across the at least one radiator panel.

[0040] In some implementations, the at least one radiator panel can be configured to increase the efficiency of the artificial light source and / or to increase the output power of the artificial light source. The radiator panel is thermally coupled to the artificial light source and can dissipate the heat generated by the artificial light source during operation. By dissipating the heat, the radiator panel can increase the operating efficiency of the artificial light source and / or increase the optical power of the light output by the artificial light source.

[0041] The selection of the size of the at least one radiator panel and the mass of the at least one radiator panel reduces the amount of artificial light source power used in a system with a given optical output power. The selection of the size and / or mass of the at least one radiator panel may be based on the total mass of the satellite. This selection may reduce the size of the satellite's photovoltaic array and increase the size of the radiator panel.

[0042] The relationship of the mass of the at least one radiator panel and the temperature of the at least one radiator panel to the efficiency of the rest of the satellite can reduce the total mass of the combination of the satellite's photovoltaic array and the at least one radiator panel. That is, the radiator panel can be configured to radiate the power left over from the inefficiency of the artificial light source. The selected mass of the radiator panel per unit output power and the mass of the satellite's photovoltaic array per unit output power can enable the total mass of the satellite including the radiator panel, the photovoltaic array, and the artificial light source to be less and / or the efficiency to be higher. That is, the configuration and temperature of the radiator panel can enable the total mass of the satellite to be less and / or the efficiency to be higher.

[0043] Implementations of the disclosed subject matter can provide a system having a satellite (e.g., satellite 200 shown in FIGS. 1 - 2B) that includes an artificial light source (e.g., diode laser 120 shown in FIGS. 1 - 2B) configured to project light on Earth or other celestial bodies, and a photovoltaic array (e.g., PV array 110 shown in FIG. 1) configured to power the artificial light source. The artificial light source can include at least one module having a plurality of delivery fibers (e.g., delivery fiber 215 shown in FIG. 2A and / or delivery fiber 216 shown in FIG. 2B), with each delivery fiber coupled to one or more laser diodes. In the system, there can be a direct electrical connection between one or more cells of the photovoltaic array (e.g., PV array 110) and the unregulated artificial light source (e.g., laser diode 120).

[0044] The maximum power point tracking device (MPPT) for the solar array and the power supply for the laser source are typically impedance modulators that adjust the effective load (in the case of the MPPT) or the source impedance (such as in the case of a laser diode driver, for example) via a switching power supply or similar device. In some implementations of the disclosed subject matter, there is no active element (such as a switching power supply) between the satellite's photovoltaic array and the artificial light source. The direct electrical connection can be a bandwidth shunt and / or a fixed shunt (e.g., a bypass) as detailed above. In some implementations, active power electronics may be used between the satellite's photovoltaic array and the artificial light source.

[0045] At least a portion of the photovoltaic array may be matched to the effective load impedance of the artificial light source. For example, as detailed above, the source impedance curve of the series - parallel arrangement of the satellite's photovoltaic array can be matched to the load impedance curve of the artificial light source. In some implementations, the matching can use the current output of the satellite's photovoltaic array to provide a current limit for the artificial light source. In some implementations, as shown in FIG. 3 and detailed above, the matching can use the current - voltage response of the artificial light source to draw maximum power from the photovoltaic array.

[0046] The foregoing description has been presented for purposes of illustration and description with reference to particular implementations. However, the exemplary description above is not intended to be exhaustive or to limit the implementation of the disclosed subject matter to the exact forms disclosed. Numerous modifications and variations are possible in light of the above teachings. These implementations are chosen and described in order to explain the principles of the implementation of the disclosed subject matter and their practical application, thereby enabling others skilled in the art to utilize various implementations with various modifications as are suited to the particular use contemplated.

Claims

1. An artificial light source configured to be disposed at a distance from the Earth or another celestial body, the artificial light source being configured to project one or more light beams onto the Earth or another celestial body, An on - ground photovoltaic array disposed in an area on the Earth or another celestial body that is 200 m - 20 km or more in any one dimension, the on - ground photovoltaic array being configured to receive the one or more projected light beams and to convert the received one or more light beams into electricity, A system having the above.

2. The system according to claim 1, wherein the peak wavelength range of the one or more light beams of the artificial light source is 750 nm - 2000 nm.

3. The system according to claim 1, wherein the peak wavelength range of the one or more light beams of the artificial light source is selected based on the efficiency range of the on - ground photovoltaic array.

4. The system according to claim 1, wherein the on - ground photovoltaic array is formed of at least one selected from the group consisting of silicon, gallium arsenide (GaAs), indium gallium arsenide (InGaAs), aluminum gallium arsenide (AlGaAs), copper indium gallium selenide (CIGS), cadmium telluride (CdTe), and perovskite.

5. The system according to claim 1, wherein the artificial light source combines light from a plurality of sources to form the one or more projected light beams.

6. The system according to claim 5, wherein the light from the plurality of sources is combined coherently or incoherently.

7. The system according to claim 1, wherein the artificial light source has a plurality of lasers.

8. The system according to claim 1, wherein the artificial light source has a plurality of modules, each module including a plurality of laser diodes coupled to a delivery fiber.

9. The system according to claim 8, wherein one or more of the delivery fibers from the plurality of modules are combined into a free - space beam that forms the one or more projected light beams from the system.

10. The system according to claim 8, wherein the one or more modules are configured to operate at a temperature of 210 K - 315 K.

11. The system according to claim 8, having at least one satellite including at least one radiator panel, wherein the one or more modules are distributed across the at least one radiator panel. **Claim 12** The system according to claim 11, wherein the size of the satellite is less than 2000 m in any direction. **Claim 13** The system according to claim 1, wherein the minimum beam parameter product (BPP) of the artificial light source is greater than 10 mm - mrad. **Claim 14** The system further includes a satellite, the artificial light source, a photovoltaic array electrically coupled to the artificial light source and configured to supply power to the artificial light source, and at least one radiator panel configured to dissipate heat generated by the artificial light source into space. The system according to claim 1, having **Claim 15** The system according to claim 14, wherein the at least one radiator panel is configured to increase at least one selected from the group consisting of the efficiency of the artificial light source and the output power of the artificial light source for a given power. **Claim 16** The system according to claim 14, wherein the selection of the size and mass of the at least one radiator panel reduces the amount of power of the artificial light source used in the system for a given optical output power. **Claim 17** The system according to claim 16, wherein the selection of at least one of the size and the mass of the at least one radiator panel is based on the total mass of the system. **Claim 18** The system according to claim 17, wherein the selection reduces the size of the photovoltaic array and increases the size of the radiator panel. **Claim 19** The system according to claim 16, wherein the relationship between the mass of the at least one radiator panel and the temperature of the at least one radiator panel with respect to the efficiency of the rest of the system reduces the total mass of the combination of the photovoltaic array and the at least one radiator panel. **Claim 20** The system according to claim 1, wherein the bandgap of the material forming the terrestrial photovoltaic array is matched to a wavelength in the range of wavelengths of the light configured to be output by the artificial light source and not longer than the wavelength corresponding to the bandgap of the material of the terrestrial photovoltaic array. **Claim 21** at least one satellite An artificial light source configured to project light onto the Earth or other celestial body, a photovoltaic array configured to supply power to the artificial light source, comprising, a direct electrical connection exists between one or more cells of the photovoltaic array and the unregulated artificial light source, at least one satellite in which at least a portion of the photovoltaic array is matched to the effective load impedance of the artificial light source, A system having.

22. The artificial light source is at least one module, a plurality of laser diodes, a plurality of delivery fibers, each delivery fiber being coupled to one or more of the plurality of laser diodes, at least one module comprising a plurality of delivery fibers, The system according to claim 21, having.

23. The matching of the effective load impedance of the artificial light source to the photovoltaic array includes matching the source impedance curve of the series-parallel arrangement of the photovoltaic array to the load impedance curve of the artificial light source, the system according to claim 21.

24. The matching uses the current output of the photovoltaic array to provide current limiting to the artificial light source, the system according to claim 21.

25. The matching uses the current-voltage response of the artificial light source to draw maximum power from the photovoltaic array, the system according to claim 21.

26. The direct electrical connection has at least one selected from the group consisting of a bandwidth shunt and a fixed shunt, the system according to claim 21.

27. at least one satellite, an artificial light source configured to project one or more light beams onto the Earth or other celestial body, a photovoltaic array electrically coupled to the artificial light source and configured to supply power to the artificial light source, and at least one satellite having a radiator panel thermally coupled to the artificial light source and configured to dissipate heat generated by the artificial light source when projecting the one or more light beams, An area on the Earth or other celestial body that is 200 m - 20 km or more in any one dimension in terms of size, configured to receive the one or more projected light beams, and configured to convert the received one or more light beams into electricity, a terrestrial photovoltaic array, A system having.

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