Lateral spectrum splitting concentrator photovoltaics: Direct measurement of component and submodule efficiency

To achieve high energy conversion efficiency, a solar module architecture called lateral spectrum splitting concentrator photovoltaics (LSSCPV) is being developed. LSSCPV can concentrate available sunlight and laterally split a single beam into bands with different spectra for absorption by different solar cells with band gaps matched to the split spectrum. Test assemblies of a sample LSSCPV architecture were constructed, each of which contains four p-n junctions and two optical pieces. Independent experiments or simulations had been implemented on the components but by using optimal assumptions. In order to examine the actual performances of all the components, which are dependent on each other and the light source, direct outdoor measurements were made. A set of self-consistent efficiency definitions was articulated and a test bed was developed to measure the parameters required by the efficiency calculation. By comparing the component efficiency items derived from the outdoor measurement and the expected values based on independent simulations, the potential opportunities for efficiency improvement are determined. In the outdoor measurement at the University of Delaware, the optical component demonstrated 89·1% efficiency. Additional assemblies were tested at the National Renewable Energy Laboratory. One assembly demonstrated 36·7% submodule efficiency, which compares favorably with the 32·6% previously reported verified submodule efficiency.