Yearly averaged light trapping for thin films

A light trapping method is proposed making use of non-tracking concentrators taking into account the solar resource over an entire year. The maximum concentration achievable was calculated to be 4.6 for a PV cell embedded in glass. This method was applied to thin film solar cells, in particular aSi and CIGS solar cells. The aSi stack consisted of ZnO, aSi, and ZnO, while the CIGS stack consisted of AZO, ZnO, CdS, CIGS, with a 30% Ga content. Simulations and optimisation routines were run to estimate the best thickness and CPC concentrator parameters. The parameter to be optimised was the total AmpHours collected over an entire year for a location in Southern California. It was found that the CPC needs to accept as broadly as possible and the thickness of the films were determined at 110nm for aSi and 1500nm for CIGS.