Assessing the suitability of metal-wrap-through solar cells for low-concentration PV systems

Abstract

The suitability of metal-wrap-through solar cells has been explored through a set of solar cells developed and optimized by Fraunhofer ISE for LCPV operation. Flexural strength testing and finite element modeling give evidence of the feasibility of MWT cells as a receiver for low concentration PV systems. MWT cells encapsulated as receivers withstand mechanical stresses equivalent to very large thermal loads (higher than those defined in the qualification standard) and show no fatigue effects after a number of bending loading cycles equivalent to their expected lifespan. Dark I-V curve screening and the comparison of electroluminescence images monitor cell damage. Large losses are found under nonuniform concentrated light, which implies that a strong tradeoff still lies between acceptance angle and efficiency. A redesign of the MWT cell metal grid or via spacing might be required to reduce series resistance losses under realistic concentrated spot illumination profiles.