Space-based 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 strength 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 provide a system that can have 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] An implementation of the disclosed subject provides a system which may have at least one satellite comprising an artificial light source configured to project light onto Earth or another celestial body, and a photovoltaic array configured to power the artificial light source. In the system, a direct electrical connection may exist between one or more cells of the photovoltaic array and an untuned artificial light source. At least a portion of the photovoltaic array may be matched to the effective load impedance of the artificial light source.

[0005] An implementation of the disclosed subject provides a system having at least one satellite which may include: an artificial light source configured to project one or more light beams onto Earth or another celestial body; a photovoltaic array electrically coupled to the artificial light source and configured to supply power to the artificial light source; and a radiator panel thermally coupled to the artificial light source and configured to dissipate the heat generated by the artificial light source when projecting the one or more light beams. The system may include a ground photovoltaic array located in an area on Earth or another celestial body which is 200m-20km or larger in any one dimension in terms of size, and which is configured to receive the projected one or more light beams and to convert the received one or more light beams into electricity.

[0006] Further features, advantages, and implementations of the disclosed subject matter may be described or become apparent from the following detailed description, drawings, and review of the claims. It should also be understood that both the above summary and the following detailed description are illustrative and intended to provide further explanation without limiting the scope of the claims. [Brief explanation of the drawing]

[0007] The accompanying drawings, included to provide a further understanding of the disclosed subject matter, are incorporated into this specification and constitute part of it. The drawings also illustrate implementations of the disclosed subject matter and, together with detailed descriptions, serve to illustrate the principles of implementation of the disclosed subject matter. No attempt is made to show structural details in more detail than may be necessary for a basic understanding of the disclosed subject matter and the various methods by which it may be implemented. [Figure 1] This document provides an example of a space-based solar power (SSP) system implemented according to the disclosed subject matter. [Figure 2A] Figures 2A and 2B show examples of SSP satellites and ground photovoltaic arrays in accordance with the implementation of the disclosed subject matter. [Figure 2B] Figures 2A and 2B show examples of SSP satellites and ground photovoltaic arrays in accordance with the implementation of the disclosed subject matter. [Figure 3] Examples of current-voltage curves for solar cells and laser diodes in arbitrary current-voltage units, in accordance with the implementation of the disclosed subject matter, are shown. [Modes for carrying out the invention]

[0008] The implementations disclosed herein relate to systems, devices, and technologies for providing space-based photovoltaic 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 attracted the most attention due to the lower technical requirements understood for them. For example, there have been numerous laboratory demonstrations of microwave amplifiers with nearly the required efficiency and power density (typically at least 70% and 1000 W / kg or more), and rectenna electronics with the required efficiency (typically at least 70%). Based on these experiments and real-world ground experiments transmitting multiple kW of power over distances of multiple kilometers (km), microwave-based SSPs have traditionally been considered more mature. However, the field has been challenged by the requirement of large apertures (several kilometers in diameter) in space requiring assembly in space, large rectenna apertures on the ground, and low permissible microwave exposure limits (typically tens of W / m²). 2 Microwave-based solutions have been held back by a variety of other limitations, including safety and / or large-scale issues driven by the following: Microwave-based solutions also face 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 issues. The shorter wavelengths used by these techniques allow for smaller apertures in space, less than 1 meter, compared to the several-kilometer scale required for microwave-based approaches. This allows the system to be a group of satellites that are launched, deployed, and operated independently. Such satellites are small enough to eliminate the need to assemble large structures in space. Optical (especially near-infrared (IR)) lasers have potentially higher safe intensity limits, although they are still around 1 kW / m². 2 It is less than (in the case of long-term exposure) and limits the usefulness of small Earth apertures that are permissible with laser sources of good beam quality. That is, approximately 1 kW / m².2 Such a safety intensity limit, which is less than 1 kW / m², applies to laser sources acting as point sources, such as those used in conventional optical SSP approaches. In contrast, the laser source used in the implementation of the disclosed subject has an intensity (power per unit area) of approximately 1 kW / m². 2 It can be an extended light source (e.g., a visually extended light source) that can safely exceed a certain limit. The artificial light source used in the implementation of the disclosed subject can be extended over a larger area of ​​the sky (e.g., across multiple satellites) and it can safely provide light without damaging the eyes of humans or animals. The beam quality of such a conventional optical SSP approach can be based on the beam parameter product (BPP) value and beam divergence, etc. A low BPP value 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 alkaline lasers) to provide both high total power and relatively good beam quality using arrays that are coupled, for example, coherently or incoherently. While these systems offer moderately high efficiency and good beam quality, their wavelengths (typically greater than 1 μm for DPSSLs) require the use of expensive photovoltaic receiver cells, such as those with expensive III-V material-based cells. Thus, in these past proposals, ground efficiency and economic considerations tend to drive optical solutions toward small receiver areas. These small areas reduce the cost of receiver arrays, but require high (unsafe) intensity to obtain moderately large power, as well as extremely precise directing and tracking to ensure that the delivered beam remains on the small receiver. The relatively low efficiency of DPSSLs, expensive receivers, the need for precise directing, and the demand for high intensity have made conventional optical SSP technologies unacceptable both technically and economically.

[0011] Conventional systems have attempted to utilize relatively short-wavelength lasers to enable small spot sizes on Earth with small apertures in space. Such configurations would be advantageous because they could minimize the cost of ground-based photodetectors and space-based telescopes. However, in order to obtain large amounts of power, such systems face an inevitable trade-off: either dramatically exceeding safe intensity on Earth or using much larger photodetectors on Earth. To date, neither option has been feasible. If maintaining safe intensity is chosen, as will be realized in the implementation of the disclosed subject discussed throughout, the resulting minimum photodetector size for large, economically interesting power levels becomes large enough, resulting in very small transmission apertures in space, or, more importantly, spatial coherence (effectively, laser beam quality) becomes less critical.

[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 Earth. Unfortunately, the use of this pumping results in laser wavelengths typically larger than 1 μm, meaning that solar cell receiver arrays must use relatively new materials and cannot utilize existing photovoltaic arrays in solar farms. Specifically, such receivers 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 alkaline laser (DPAL) systems) use shorter wavelengths but suffer from efficiency losses, as well as similar cost and complexity problems to the aforementioned diode-pumped and / or diode-pumped solid-state systems.

[0013] Implementations of the disclosed subject matter may utilize fiber-coupled diode laser arrays, as the importance of spatial coherence decreases when using sufficiently large ground receivers. This configuration can increase electrical-optical efficiency by avoiding intermediate optical-optical lathing conversions and can also reduce system mass. Implementations of the disclosed subject matter can utilize larger receiver apertures of ground photovoltaic arrays that may be provided by comparable-sized solar power plants and receivers. Implementations of the disclosed subject matter can use artificial light sources in space that emit beams with low coherence, 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 the artificial light source (e.g., laser efficiency). Implementations of the disclosed subject matter can shift the wavelength of the artificial light source to a region that can easily penetrate the atmosphere and can be converted with high efficiency by conventional solar arrays.

[0014] Figure 1 shows a schematic representation of a space-based solar power system 10 according to an implementation of the disclosed subject matter. One or more photovoltaic (PV) arrays 110 may be placed 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 it to a receiver 130 on Earth or another celestial body. The satellite 200 may include artificial light sources (e.g., diode lasers 120) that can be powered by the electrical energy from the PV arrays 110. The diode lasers 120 can be coupled to the PV arrays 110 and used to transmit the received and / or stored power to a ground-based photovoltaic array (e.g., receiver 130) via one or more beams 300. In some implementations, the diode lasers 120 may be directly coupled to the PV arrays 110, as described in detail below. The receivers 130 may be configured to be sized to accommodate broad or incoherent beam patterns from the diode lasers 120. The receiver 130 can use a conventional PV array, which is common in modern solar power plants. The wavelengths of one or more beams 300 output from the laser diode 120 can be selected to match the most efficient absorption wavelengths (one or more) of the receiver 130, as will be 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, for example, via a conventional power grid 140, a battery-based or similar storage system 150, or something similar. Although one satellite 200 is shown in Figure 1, there may be multiple satellites 200 capable of outputting beams 300 to one or more receivers 130.

[0015] The efficiency of diode laser 120 may be inversely correlated with junction temperature. In laboratory tests, laser diodes with room-temperature efficiencies of 60-65% can approach 75-85% efficiencies when cooled to temperatures below 0°C. Some laboratory tests yield 85% diode efficiency at -40°C, while others establish efficiencies of >70% at around 0°C.

[0016] The inverse correlation between efficiency and temperature has little effect on typical laser diode systems because the energy cost of refrigeration and / or cooling the laser diode is greater than the energy savings from increased efficiency. However, this inverse correlation between efficiency and temperature becomes important when operating laser diodes in space applications, as in the implementation disclosed herein. In space, the background temperature is extremely low, provided that thermal inputs from the sun, Earth, and / or other celestial bodies are adequately addressed. These thermal inputs to the SSP according to the disclosed subject can be addressed through shielding, blocking, and / or high emissivity / low absorptive coatings or materials. Thus, virtually any low temperature in space can be limited only by solar exposure, materials, and heat flux per unit area. For example, materials can be selected to achieve an economically sufficiently low mass. That is, if low-cost, highly conductive materials are selected, there will be more radiator panels per unit waste heat, allowing the diode laser 120 to operate at lower temperatures. The lighter the radiator panel (for example, the higher the conductivity per unit mass of the fins), the lower the temperature of the laser (e.g., diode laser 120) can be. This can reduce both the required power and the size of the PV array (e.g., PV array 110).

[0017] Therefore, when using diode lasers in space, particularly in power beam applications, this temperature-dependent efficiency effect can be utilized, along with low-mass, low-temperature radiators and advanced low-absorption and / or high-emissivity coatings, to achieve substantially higher efficiencies than those of conventional laser diodes. While this effect is generally known for terrestrial laser applications, it has not been applied to space applications to date, particularly to power beam applications in space using diode lasers.

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

[0019] By selecting an artificial light source (e.g., a laser) that efficiently generates wavelengths close to the bandgap of conventional solar array materials, the overall system efficiency can be increased and / or maximized. Since the receiver technology of the disclosed subject implementation utilizes existing mass-produced large-area solar cells / modules / farms, the need for narrow beams to reduce system costs is reduced and / or eliminated. This combination offers two advantages. While diode-pump lasers have better beam quality than direct diode lasers, their longer wavelengths require new types of receiver cell technology (e.g., solar arrays fabricated from materials different from conventional ones), and their overall transmission efficiency is lower. Therefore, the disclosed implementation can use a diode laser as the artificial light source without using an intermediate step for pumping different materials.

[0020] An implementation of the disclosed subject matter can directly utilize a diode laser by incoherently coupling light from multiple diodes into a transport fiber. The beams from the laser and transport fiber can be combined and then directed, or simply directed to a ground receiver through an optical system. This configuration can enable improvements in beamed solar power, as will be discussed later in relation to Figures 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 a virtually flat section 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 particular point where the current rapidly drops 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 the maximum power.

[0023] In both the case of lasers and the case of solar cells, 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 solar cells and diode lasers effectively at a constant level for beamed space solar power, implementations of the disclosed subject matter can eliminate both sets of power electronics (i.e., power electronics for lasers and power electronics for solar cells).

[0024] By matching the number of series-parallel arrangements of solar cells and laser diodes, 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 that was conventionally required for stability by matching the I-V curves of the two devices and by matching the number of series-parallel arrangements of solar cells and laser diodes 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 may be stable over time but output slightly less power may be used.

[0026] Figures 2A-2B show an example of the SSP satellite 200 and ground receiver 130 of Figure 1, according to an implementation of the disclosed subject matter. The satellite 200 may have a plurality of modules 202, which 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. One or more PV arrays 110 can convert sunlight into electricity. One or more laser diode modules 120 can convert the electricity into optical power and deliver the optical power to the fibers. For example, as shown in Figure 2A, the output of one or more laser diode modules 120 can be provided to the output fibers 215, and one or more of the output fibers 215 may be coupled using a fiber combiner 220 to form one or more delivery fibers 230. Alternatively, the output from 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, Figure 2B shows that the outputs of one or more laser diode modules 120 are supplied to a delivery fiber 216, and the beams from the delivery fiber are combined by a free-space beam combiner 217 and supplied to a delivery telescope 240.

[0027] As shown in Figures 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 to one or more ground receivers 130 in a divergence that can be matched. The laser diode module 120 and receivers 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, one or more output fibers 215 from the laser module 120 can be coupled to a smaller number of delivery fibers 230 using a fiber combiner 220, as shown in Figure 2A. As shown in Figure 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 Figures 2A-2B, the coarse aiming mirror 250 can be used to redirect the output beam 300 of the transmission telescope 240 toward the Earth and / or other celestial bodies, providing a coarse aiming of those beams toward one or more receivers 130 which may be part of a solar power plant on Earth and / or other celestial bodies.

[0028] As described above, the implementations disclosed herein benefit from developments and insights that were not available or fully utilized in conventional SSP systems. The receiving ground arrays used in the implementations of the disclosed subject matter do not need to be very small and can be about the size of a modern solar power plant. Using a large receiving spot size (e.g., the area of ​​a solar power plant receiver) can allow the energy involved to be exceptionally safe compared to conventional approaches. A large receiving spot size can allow a relatively inexpensive but efficient incoherently coupled diode laser array to transmit orbital power to a ground receiver. The artificial light sources used in the implementations of the disclosed subject matter can extend over a larger area of ​​the sky (e.g., across multiple satellites), which can safely deliver light to a large receiving spot size (e.g., a ground receiver) without damaging the eyes of humans or animals. Existing solar power plants can be used, as some implementations may utilize highly efficient NIR wavelength lasers, such as those described throughout in relation to the disclosed implementations. For example, illuminating existing solar power plants with wavelengths that match those that conventional solar cells can efficiently receive and convert into electricity can lead to efficiency increases that were not achievable with conventional systems. Operating laser diodes using orbital solar panels can be self-current-limited and eliminate the need for most power electronics, further reducing system complexity and cost without sacrificing efficiency.

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

[0030] The artificial light source may be the diode laser 120 shown in Figures 1-2B. The peak wavelength range of one or more light beams of the artificial light source may be 750 nm-2000 nm. For example, the artificial light source for the system may 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 peak wavelength ranges for the artificial light source may include wavelengths of 808 nm, 915 nm, and / or 976 nm. In some implementations, the minimum beam parameter product (BPP) of the artificial light source may 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 may have a range of 10-100 mm-mrad.

[0031] Artificial light sources may be selected based on the efficiency range of the ground photovoltaic array, along with its peak wavelength range. The ground photovoltaic array may be the ground receiver 130 shown in Figures 1-2B. For example, the ground photovoltaic array may 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 to electricity. Based on the efficiency of one or more materials forming the ground photovoltaic array, artificial light sources may be selected that have a peak wavelength range that matches the efficiency of the one or more materials in the ground photovoltaic array. That is, the band gap of the materials forming the ground photovoltaic array may be matched to a range of wavelengths of light configured to be output by the artificial light source, such that the band gap of the materials forming the ground photovoltaic array is not longer than the wavelength corresponding to the band gap of the materials in the ground photovoltaic array, as described in detail above.

[0032] Artificial light sources include laser diodes, fiber lasers, and diode pump solid-state lasers. This can be multiple lasers, including several similar lasers. In some implementations, the laser of the artificial light source may be multimode and may have lower coherence than a single-mode laser. Coherent light is light that has photons that vibrate at the same frequency and have wavelengths that are in phase. In contrast, the photons of incoherent light vibrate at different frequencies and their wavelengths are not in phase with each other. The beam of an artificial light source with a multimode laser can be said to be less coherent than, for example, a coherent beam from a single-mode laser.

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

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

[0035] Light from multiple light sources can be coupled coherently or incoherently. When light is coupled coherently, the coupled light may have photons that vibrate at the same frequency and have the same phase waveform. When light is coupled incoherently, the coupled light may have photons that vibrate at different frequencies and have waveforms that are out of phase with each other.

[0036] In Figure 2A, the delivery fiber 230 can be coupled to multiple delivery telescopes 240. In Figure 2B, the output of the free-space beam combiner 217 can be supplied to the delivery telescopes 240. In Figures 2A-2B, the beam output from the delivery telescopes 240 can be reflected by the mirrors 250 to form the output beam 300. In some implementations, the optical beam projected by the artificial light source may have reduced coherence when a multimode diode laser is used as the artificial light source.

[0037] The output beam can be directed to a ground-based photovoltaic array (e.g., receiver 130) located on Earth or in an area on another celestial body. In some implementations, the ground-based photovoltaic array can be part of a solar power plant that can receive one or more of the output beams 300.

[0038] As shown in Figures 1-2B, the system may include a satellite having an artificial light source (e.g., a diode laser 120), a photovoltaic array (e.g., a 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., a radiator panel 210). The satellite's photovoltaic array may 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 multijunction cell, capable of converting light into electricity.

[0039] The size of the satellite can be less than 1000m, less than 1200m, less than 1500m, less than 1800m, less than 2000m, and / or any other preferred distance in any direction. The artificial light source can be thermally coupled to at least one radiator panel, which dissipates heat from the artificial light source when it is operating. That is, the at least one radiator panel can be configured to dissipate the heat generated by the artificial light source into 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, at least one of the radiator panels may be configured to increase the efficiency of the artificial light source and / or 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 heat, the radiator panel can increase the operating efficiency of the artificial light source and / or increase the light power of the light output by the artificial light source.

[0041] The selection of the size and / or mass of the at least one radiator panel reduces the amount of artificial light source power used in the system of a given optical output power. The selection of the size and / or mass of the at least one radiator panel may also 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 between the mass of the at least one radiator panel and the temperature of the at least one radiator panel and the efficiency of the rest of the satellite may reduce the total mass of the satellite's photovoltaic array and the at least one radiator panel combined. That is, the radiator panel may be configured to radiate the power remaining from the inefficiency of the artificial light source. The selected mass of the radiator panel per unit power output and the mass of the satellite's photovoltaic array per unit power output may allow for a lower total mass of the satellite, including the radiator panel, photovoltaic array, and artificial light source, and / or higher efficiency. That is, the configuration and temperature of the radiator panel may allow for a lower total mass of the satellite and / or higher efficiency.

[0043] An implementation of the disclosed subject provides a system that may have a satellite (e.g., satellite 200 shown in Figures 1-2B) comprising an artificial light source (e.g., diode laser 120 shown in Figures 1-2B) configured to project light onto the Earth or another celestial body, and a photovoltaic array (e.g., PV array 110 shown in Figure 1) configured to power the artificial light source. The artificial light source may include at least one module having multiple delivery fibers (e.g., delivery fiber 215 shown in Figure 2A, and / or delivery fiber 216 shown in Figure 2B), each delivery fiber being coupled to one or more laser diodes. In the system, a direct electrical connection may exist between one or more cells of the photovoltaic array (e.g., PV array 110) and an untuned artificial light source (e.g., laser diode 120).

[0044] The power supplies for the maximum power point tracking (MPPT) for the solar array and 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) via a switching power supply or similar device. In some implementations of the disclosed subject matter, no active elements (such as a switching power supply) are present between the satellite's photovoltaic array and the artificial light source. The above direct electrical connection may be a bandwidth shunt and / or a fixed shunt (e.g., a bypass), as described in detail 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 described in detail above, the source impedance curve of a series-parallel arrangement of the satellite's photovoltaic array may be matched to the load impedance curve of the artificial light source. In some implementations, the matching may use the current output of the satellite's photovoltaic array to provide current limiting to the artificial light source. In some implementations, as shown in Figure 3 and described in detail above, the matching may use the current-voltage response of the artificial light source to extract maximum power from the photovoltaic array.

[0046] The above description is provided with reference to specific implementations for illustrative purposes. However, the illustrative descriptions above are not intended to be exhaustive, nor to limit implementations of the disclosed subject matter to the very forms disclosed. Numerous modifications and variations are possible in light of the above teachings. These implementations are selected and described to illustrate the principles of implementations of the disclosed subject matter and their practical applications, thereby enabling those skilled in the art to utilize these implementations and various other implementations with various modifications that may be suitable for specific intended uses.

Claims

1. An artificial light source configured to be positioned at a certain distance from the Earth or another celestial body, and configured to project one or more light beams onto the Earth or other celestial body, A ground photovoltaic array is located in an area on the Earth or another celestial body that is 200 m - 20 km or more in any one dimension, and is configured to receive one or more projected light beams and to convert the received one or more light beams into electricity. It has, The band gap of the material forming the ground photovoltaic array is matched to a range of wavelengths that are not longer than the wavelength corresponding to the band gap of the material in the ground photovoltaic array, where the wavelength of the light configured to be output by the artificial light source is the same as the wavelength of the light. system.

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

4. The system according to claim 1, wherein the ground photovoltaic array is formed from 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 multiple sources to form 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 one or more light beams projected from the system.

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

11. The system according to claim 8, wherein the system has at least one satellite including at least one radiator panel, and the one or more modules are distributed across the at least one radiator panel.

12. The system according to claim 11, wherein the size of the satellite is less than 2000 m in any direction.

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.

14. The system further, It is a satellite, The artificial light source, A photovoltaic array configured to be electrically coupled to the artificial light source and to supply power to the artificial light source, A satellite having at least one radiator panel configured to dissipate heat generated by the artificial light source into outer space, The system according to claim 1, having the following features.

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 to a given power.

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.

17. The system according to claim 16, wherein the selection of at least one of the size and mass of the at least one radiator panel is based on the total mass of the system.

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.

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 and the efficiency of the rest of the system reduces the total mass of the photovoltaic array and the at least one radiator panel combined.

20. It is at least one satellite, An artificial light source configured to project light onto the Earth or another celestial body, A photovoltaic array configured to supply power to the artificial light source, Includes, A direct electrical connection exists between one or more cells of the photovoltaic array and the unadjusted artificial light source. At least a portion of the photovoltaic array is matched to the effective load impedance of the artificial light source, at least one satellite A system that has

21. The aforementioned artificial light source is It is at least one module, Multiple laser diodes, A module comprising a plurality of delivery fibers, each of which is coupled to one or more of the plurality of laser diodes, The system according to claim 20, having the following features.

22. The system according to claim 20, wherein the matching of the effective load impedance of the artificial light source with respect to the photovoltaic array includes matching the source impedance curve of the series-parallel arrangement of the photovoltaic array with the load impedance curve of the artificial light source.

23. The system according to claim 20, wherein the matching uses the current output of the photovoltaic array to provide current limiting to the artificial light source.

24. The matching is performed using the current-voltage response of the artificial light source to extract maximum power from the photovoltaic array, according to claim 20.

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

26. It is at least one satellite, An artificial light source configured to project one or more light beams onto the Earth or another celestial body, A photovoltaic array configured to be electrically coupled to the artificial light source and to supply power to the artificial light source, and A satellite having at least one radiator panel, which is thermally coupled to the artificial light source and configured to dissipate the heat generated by the artificial light source when projecting one or more light beams, A ground photovoltaic array is located in an area on the Earth or another celestial body that is 200m-20km or larger in any one dimension, and is configured to receive one or more projected light beams, and to convert the received one or more light beams into electricity. It has, A direct electrical connection exists between one or more cells of the photovoltaic array and the unadjusted artificial light source. At least a portion of the photovoltaic array is matched to the effective load impedance of the artificial light source. system.

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