Real-world PV Module Degradation across Climate Zones Determined from Suns-Voc, Loss Factors and I-V Steps Analysis of Eight Years of I-V, Pmp Time-series Datastreams

Abstract

We report here on performance and mechanistic degradation analysis of 8 years of I-V, Pmp time-series for eight commercial crystalline silicon photovoltaic (PV) modules, located in three distinct climate zones. A data-driven algorithm has been applied to extract I-V features and detect steps in 3.2 million I-V curves. Using the Y ear-on-Y ear determined linear PLR, we found that one brand F (glass-backsheet) module has a much greater (more negative) PLR than another brand G (double glass) in BWh hot desert climate zone. BSh hot semi-arid is shown to be the most aggressive climate zone of the three in which modules were fielded, the third being ET tundra climate. The mechanisms causing most significant power loss for modules in BWh, BSh and ET climate zones are current mismatch (shading), cell shunting, and series resistance, respectively based on Analytic Suns-Voc analysis derived from outdoor I-V curves. Using steps observed in the I-V curves of the systems we are also able to identify and characterize the shading of specific modules.