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Large Area Solar Simulator for Next Generation Solar Panels

Description:

TECHNOLOGY AREA(S): Space Platforms 

OBJECTIVE: Develop large-area, low-cost, solar simulator capable of AM0 illumination of solar modules composed of multijunction solar cells with more than three subcells. 

DESCRIPTION: The 30% efficient InGaP/InGaAs/Ge triple junction solar cell has been considered state-of-practice among nearly all major government and commercial spacecraft for over a decade [1]. The U.S. Air Force (AF), in collaboration with the U.S. space solar cell industry, continues to drive improvements of multijunction solar cells to improve size, weight, and power (SWaP) metrics. Higher solar cell efficiency and novel array architectures provide mission enabling power levels and reduce system-level costs. To continue pushing the limits of SWaP metrics, new solar cell architectures are being developed, such as the inverted metamorphic multijuction (IMM) architecture [2]. Some of these designs contain more than three subcells and thus require new specialized characterization equipment. Accurate electrical characterization (e.g., current-voltage (I-V) measurements) of these new space solar cells require new tools such as multi-zone solar simulators that are capable of accurately simulating the AM0 spectrum and give the ability to tune the spectral intensity within certain spectral ranges [3]. In addition to testing at the cell level, panel-level integrators must use large-area solar simulators, such as a large-area pulsed solar simulator (LAPSS) [4], to characterize the output at the panel level. The measurements gained from using these tools give confidence in the electrical output at a high level of integration (i.e., including cells, interconnects, wiring, bypass/blocking diodes, etc.). In recent years, cell development has outpaced development of large-area simulators capable of testing panels that incorporate new, >3 subcell multijunction cell architectures. The Air Force is seeking to develop a large-area pulsed solar simulator capable of AM0 illumination of a 2m X 2m space solar array panel that contains solar cells with >3 subcells. The simulator should be capable of 2% areal uniformity and 2% temporal stability, allow for adjustable intensity, and be spectrally tunable to accommodate different solar cell architectures. . The pulse length should allow for a full I-V sweep or for a data point(s) to be taken per pulse so long as the panel can be adequately thermally controlled. The simulator developed under this program should be capable of satisfying the illumination requirements of the AIAA-S112 qualification for space solar array panels. Recently, LED based solar simulators have been used for characterizing CubeSat arrays [5] and show promise for large area applications. However, due to their relatively small illumination area, many LEDs must be used which adds complexity. These challenges may be overcome though with proper cooling and electrical integration and control. This call for proposals does not require a solution based on LEDs but would welcome potential ideas incorporating them. 

PHASE I: Develop large area solar simulator designs that enables characterization of large area (2m X 2m) space solar array panels under the AM0 spectrum. Perform preliminary testing and analysis of the identified options to support down select and Phase II development planning. 

PHASE II: Mature the most promising large area solar simulator design and perform required testing and analysis to determine the uniformity and stability of the electrical characterization at the panel level using the simulator as an illumination source. The goal is to have the technology matured to TRL 4 or higher at the end of the Phase II effort. 

PHASE III: Deliver full-scale AM0 solar simulator capable of illuminating 2m X 2m solar module with 2% areal uniformity and 2% temporal stability. The simulator should be capable of satisfying AIAA S-112 requirements. 

REFERENCES: 

1. King, R. R., et al. "Next-generation, high-efficiency III-V multijunction solar cells." Photovoltaic Specialists Conference, 2000. Conference Record of the Twenty-Eighth IEEE. IEEE, 2000.; 2. Pantha, Bed, Mark Stan, and Daniel Derkacs. "Inverted metamorphic multijunction solar cell." U.S. Patent Application No. 15/352,941.; 3. Montgomery, Kyle H., et al. "Characterization of a TS-Space quad-source solar simulator." Photovoltaic Specialists Conference (PVSC), 2012 38th IEEE. IEEE, 2012.; 4. Kruer, Mark A. "Large area pulsed solar simulator." U.S. Patent No. 5,984,484. 16 Nov. 1999.

KEYWORDS: High-efficiency, Solar Cell, Large Area Pulsed Solar Simulator, Inverted Metamorphic 

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