The Influence of Incidence Angle on the Reliability of Photovoltaic Modules: Lessons Learned

Abstract

To maximize energy yield, photovoltaic (PV) system designers optimize parameters that enhance plane-of-array irradiance, with module tilt angle being a key factor. However, higher irradiation also raises operating temperatures, accelerating degradation mechanisms. While simulations offer insight, experimental validation is essential to assess tilt angle impacts on long-term reliability. This study presents an indoor accelerated aging test replicating variations in UV exposure linked to tilt angle. passivated emitter and rear contact (PERC) c-Si mini-modules underwent controlled UV soaking, elevated temperatures, and humidity to replicate prolonged outdoor conditions. Degradation was monitored through I-V curve measurements and electroluminescence imaging. Encapsulant discoloration and photobleaching primarily reduced short-circuit current (I SC), while boron-oxygen light-induced degradation (BO-LID) and light and elevated temperature-induced degradation (LeTID) contributed to I SC and open-circuit voltage (V OC) losses. Further UV doses of 34, 17, and 6.5 kWh/m2, representing different tilt angles, caused maximum power (P max) reductions of 0.79%, 0.61%, and 0.35%, respectively. These results highlight the need for further study of BO-LID and LeTID in PERC and other c-Si PV technologies. The observed tilt angle effects cannot be generalized to long-term degradation. Further investigation into long-term impact by applying stabilization methods to the modules and afterward fitting the data to degradation models is needed to draw final conclusions.