Performance evaluation of CLEFT GaAs/CuInSe2 tandem cell circuits through solar simulator testing and computer modeling

CLEFT GaAs/CuInSe₂ (CIS) tandem cell development has proceeded to circuit fabrication and testing. Solar simulator tests have been conducted to characterize tandem cell circuits under various environments and configurations. Three test panels were fabricated. each containing up to 30 tandem cell modules. These panels contained circuits with the ratio of CIS cells in series to each series GaAs cell from 2:1 to 3:1 (defined as a series ratio), and circuits with 0% to 6% Imp mismatch between two substrings in series, where each substring consisted of three CIS cells in series to three GaAs cells in parallel. One panel contained a single circuit of ten closely matched 3:1 substrings in series. The electrical performance of these circuits was measured over 18°C to 55°C. Electrical performance test results demonstrated that a 3:1 series ratio maximizes circuit output at 28°C and that current mismatch between substring circuits must be tightly controlled to prevent reverse voltage bias operation