Experimental Investigation of the effects of Potential Induced Degradation of Poly-crystalline Photovoltaic Modules /

Abstract

Potential induced degradation (PID) is one of the most critical degradation phenomena, affecting the reliability of photovoltaic solar modules by causing power losses up to 30% on the system level. In this research, PID is induced on poly-crystalline modules in an environmental chamberin accelerated temperature and humidity conditions under the application of high voltage stress to investigate the degradation phenomenon. The primary focus of this paper is to quantify the degradation extent of PV modules with different encapsulant and superstrate/glass types. The encapsulant types investigated in this work are Ethylene-vinyl acetate (EVA) and newly developed Polyvinyl butyral (PVB). The superstrate types investigated are soda-lime glass and quartz. The progression and severity of degradation were determined through Current-Voltage measurements and Electroluminescence imaging, revealing losses in Maximum power and Fill-factor. The leakage current was measured during the entire PID test and no correlation between leakage current and power was observed. It was demonstrated that the PID loss is strongly depending on the electrical and physical properties of the superstrate and encapsulant types. The module with Quartz/EVA configuration experienced lower (17%) PID losses compared to the Soda-lime/EVA module (32%). Similarly, the module with Soda-lime /PVB configuration experienced lower (10%) PID losses compared to the Soda-lime/EVA module (32%). While the module having both the quartz superstrate and PVB encapsulant, experienced the lowest PID with % degradation in power up to only 1%. The extent of degradation is explained based on the electrical and ionic conductivities of the superstrate and the encapsulant.