Assessment of spectral effects on outdoor characterization of PV modules using silicon reference cells with spectral filters

Abstract

This article describes outdoor temperature-controlled measurement of various photovoltaic (PV) modules fabricated using different technologies and using reference cells with spectral filters. Short-circuit current measurements of all PV modules and reference cells were recorded simultaneously using 16-bits Keysight digitizers and high-resolution Agilent multimeters. The spectral incompatibility factor was calculated considering the spectral response of each device and the spectrum measured outdoors. Corresponding spectra were also generated by the simple model of atmospheric radiative transfer of the sun SMARTS2 and were additionally used to compare the spectral incompatibility factors. The validation of the measurement method was demonstrated by comparing the incompatibility factor calculated with variation of the short-circuit current relationship between the device under test and the reference cell over time. Additionally, it was evaluated how the relationship between spectral variation of irradiance and the spectral response of different technologies affects the productivity in thin-film modules. Main observation from measurements (performed in Labsol) was that a-Si/μ-Si, CdTe, and triple a-Si junction converted 0.21%, 2.47%, and 3.65% more irradiation into electric current (in summer), respectively, compared to c-Si technology. The PV CIGS module converted on average 0.26% more irradiation into electric current in winter compared to c-Si technology. The results help to understand the spectral effects on the working of outdoor PV module and the relationships between measured and modeled spectra, as well as errors introduced by the spectral incompatibility factor.