LAUSR

A total of five different types of photovoltaic (PV) modules were comparatively analyzed in terms of electrical output, efficiency, and relative efficiency losses, based on infield data collected in a temperate mountain climate, to outline the influence of the high relative environmental humidity on the PV conversion efficiency during time intervals with clear sky and low amounts of incident solar irradiance. The mono- and poly-crystalline silicon, cadmium telluride (CdTe), copper indium selenium (CIS), and copper indium gallium selenide (CIGS) modules mounted on a fixed tilted, South-oriented platform were individually monitored or in groups of modules using power optimizers. The electrical energy production, the PV conversion efficiency, and the relative efficiency losses were correlated with the weather data, and the analysis discusses the lower electrical energy output during periods with high relative air humidity. The analysis indicates that in a temperate climate, during days with high humidity intervals similar to the ones discussed in the paper, crystalline silicon modules have the lowest efficiency losses, followed by CdTe, CIGS, and CIS modules. The results can be useful for PV system designers, installers, and end-users of PV systems for a better system design and for a more accurate prediction of the daily energy production.