Over 30% efficient InGaP/GaAs/GaSb cell-interconnected-circuits for line-focus concentrator arrays

While monolithic multi-junction cells are preferred for flat plate arrays, mechanically stacked multi-junction cells have significant advantages for solar concentrator applications. Reasons for this are that the mechanical stacked configuration with high efficiency gallium antimonide cells allows utilization of a much wider range of the solar energy spectrum and the ability to use voltage matched interconnects resulting in full use of low bandgap cell currents. With the success of the 2.5 kW line-focus concentrator array on NASA's Deep Space 1 mission, cell performance under concentration has become an important issue. Data is presented showing 30% efficiency for the InGaP/GaAs/GaSb stacked cell, and a simple two terminal voltage-matched circuit that mounts into a line-focus array is described.