Quantifying the optical losses in back-contact solar cells

A procedure to quantify the optical loss mechanisms in back-contact solar cells is presented. It incorporates recent developments in optical simulation that yield rapid and precise results. The procedure includes spectrophotometry, ellipsometry, quantum efficiency measurements, ray tracing, and the thin-film matrix method. The paper shows how experiments and simulation can be combined to quantify reflection from the front surface, absorption in the antireflection coatings, non-ideal light trapping, and free-carrier absorption-all in terms of a `lost generation current'. The procedure is demonstrated on a back-contact solar cell with single-layer and double-layer antireflection coatings. It is extendable to other cell structures.