The effects of the high voltage stress and other environmental conditions on crystalline silicon photovoltaic module performance have not been included in the IEC 61215 or other qualification standards. In this work, we are to evaluate the potential induced degradation on p type crystalline silicon PV modules by three cases, one case is in room temperature, 100% relative humidity water bath, another is in room temperature, the front sheet coverage with aluminum foil and the other is in the 85°C, 85% relative humidity climate chamber. All the samples are applied with the -1000 V bias to active layers, respectively. Our current-voltage measurements and electroluminescence results showed in these modules power loss of 37.74%, 11.29% and 49.62%, respectively. These test results have shown that among high voltage effects the climate chamber is the harshest and fastest test. In this article we also showed that the ethylene vinyl acetate volume resistivity and soda-lime glass ingredients are important factors to PID failure. The high volume resistivity which is more than 10¹⁴ Ω·cm and Na less contents glass will mitigate the PID effect to ensure PID free.

In this paper, we discussed the field failures of the brownish discolored lines like snail trails in PV modules. We were successful simulation snail trails in laboratory and outdoor field. We had found out some types EVA (ethylene vinyl acetate) encapsulants and back sheets which had the serious snail trails but others were snail trails free. Furthermore, according to IEC 61215 accelerated aging testing, we also found only within 2% power loss after these modules impacted by snail trails. The main power losses over 5% were come from cell micro cracks before snail trail formation. That snail trails occurrence means solar cells should have micro cracks. In here, we contributed the snail trail effects and avoided the failures in future photovoltaic modules performance.

The more and more solar power requirements and balance of system (BOS) cost saving issues, photovoltaic power plants have increasing system voltage, in Europe, for example, the system voltage requirements up to 1000 volts to 1500 volts. Solar module reliability expose to the high voltage stress (HVS) need reassessment. It is well-known that HVS can lower the PV power significantly that means potential induced degradation (PID) effect. However, the effects of the PID and other environmental conditions on module performance have not been included in the IEC qualification standards yet. In this paper we review various PV module type, example MG-Si, poly-Si, CIGS module and encapsulant sheets performance suffer high voltage stress effect. To evaluate module durability in the presence of continuous high voltage we used four accelerated tests to qualify the HVS effect. The first one is under room temperature, 100% relative humidity (RH), second method is room temperature and aluminum foil covered the front sheet, the third method is climatic chamber test at 85℃and 85% RH and the last one is the 60°C and 85%RH with -1000V bias applied to active layer, respectively. The I-V characteristics and Electroluminescence (EL) images have been measured after several time steps to quantify the degradation process of each module. Besides the recovery characterization was also investigation.

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