Spectral Analysis of Various Thin-Film Modules Using High Precision Spectral Response Data and Solar Spectral Irradiance Data

This paper presents the results of high-precision indoor and outdoor measurements of different PV module technologies performed at the TÜV Rheinland PV test laboratory, Cologne, from May 2010 to September 2012. Modules based on CdTe, CI(G)S, a-Si, a-Si/μ-Si, a-Si/a-Si and c-Si (mono and poly) semi-conductors were analysed non-destructively as to their spectral behaviour by means of a new test apparatus and differences specific to the technology determined. Following indoor testing the modules were exposed outdoors for one year, with the maximum power point PMPP and the I/V-curves continually measured with the corresponding solar spectrum. This extensive database allows a description of the spectral conditions at the test-site in Cologne with the APE method. As the next step we analysed the module performance and energy yield for the different technologies. We theoretically calculated the photo-current by integrating the spectral response data and spectral measurements and compared the results against the data from real outdoor measurements corrected for temperature and irradiance.