Sine-limiting microcell solar concentrators for space.

ABSTRACT

Microcell concentrating photovoltaics (µCPV) have the potential to improve performance and reduce the cost of solar power in space. Here, we introduce an ultracompact V-cone tailored edge ray (V-TERC) concentrator, rooted in nonimaging optics, which enables operation near the sine limit. Relative to previous space µCPV implementations, this concentrator design enables an approximate four-fold increase in concentration ratio for a given acceptance angle and specific power. We validate the design through ray tracing simulations and construction of a proof-of-concept system that consists of a 650 × 650 µm2 triple-junction microcell bonded to a 3.1 mm-thick prototype V-TERC optic. In outdoor testing on a sunny day, the system achieves a power conversion efficiency of 30% at a geometric gain of 137× with a specific power of 90 W kg-1 and an acceptance angle of ±4.5°. This is a record combination for µCPV to date and represents an important step toward increasing efficiency and lowering the cost of solar power in space.