The highest efficiency triple-junction GaAs solar cell in the world has achieved 42.3% (42.2% efficiency at 500 times of concentration) under the conditions of 406 times solar radiation spotlight (406 suns), 1.5 (AM1.5) and 25 ℃ atmospheric optical mass. The development is part of the NREL incubator subcontract at the National Renewable Energy Laboratory (NREL). The record has also been confirmed by NREL.
Gallium arsenide entered the practical stage in 1964. Gallium arsenide can be made into a semi-insulating high-resistance material with a resistivity of more than 3 orders of magnitude higher than that of silicon and germanium, which can be used to make integrated circuit substrates, infrared detectors, gamma photon detectors, etc. Because its electron mobility is 5-6 times higher than silicon, it has been importantly used in the manufacture of microwave devices and high-speed digital circuits.The theoretical best Eg value of the bottom and top batteries with current matching: Eg1=1.65–1.8 eV for the top battery, and Eg2=1.0–1.15 eV for the bottom battery. The theoretical single solar AMO efficiency of tandem solar cells with these bandgap values is about 32.5%
The efficiency is further improved by 34% (AM0, 25°C, and 15 suns (SUN) are obtained in the three-junction mechanically stacked voltage matching circuit based on the monolithic GaInP-GaAs double-junction upper cell and GaSb lower cell. In [65]. At a concentration of 15suns-AM0, the upper cell efficiency of GaInP-GaAs is 27.5%, and the lower cell efficiency is 6.5%. In order to obtain two terminal circuits, seven GaSb cells are connected in series to ensure that the output voltage (Vmp) is 7×0.375 V= 2.63 V, for two InGaP-GaAs junction units connected in parallel, slightly more than 2.4 V Vmp.
Based on these stacks in the ultra-light stretch lens array [66], the efficiency of the smallest module is estimated to be 30%, which is characterized by a total efficiency of 26% and an array power density of 350 W/m2.