Contribution of PV Encapsulant Composition to Reduction of Potential Induced Degradation (PID) of Crystalline Silicon PV Cells
| Autor: | Reid, C., Ferrigan, S., Fidalgo, I., Woods, J. |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: | |
| DOI: | 10.4229/28theupvsec2013-4av.5.49 |
| Popis: | 28th European Photovoltaic Solar Energy Conference and Exhibition; 3340-3346 This paper reports the results of evaluation of several photovoltaic (PV) encapsulant compositions based upon EVA (ethylene vinyl acetate copolymer), and POE (polyolefin elastomer) that have been studied for PID resistance with crystalline silicon PV cells. The laboratory screening method utilized is a single PV cell module with an electrical circuit that applies negative bias to the PV cell and continuously monitors the shunt resistance through the PV cell during exposure to stress factors. Full-size 60 cell modules have also been manufactured and tested with methods to force PID behavior. During both the laboratory and full-scale module tests, several key encapsulant compositional variables were found that control PID. Of greatest importance for PID resistance is the volume resistivity (VR) of the encapsulant and stability of volume resistivity (or wet insulation resistance) during the aging protocol used for the PID test. Moisture vapor transmission rate (MVTR) is also a significant variable for PID. High temperatures (60°C or 85°C) are used to accelerate the transfer of positive charges from glass to the PV cell. It is expected that encapsulants with higher VR and lower MVTR at the elevated test temperature will yield less charge transfer through the encapsulant. Volume resistivity above 1015 ohm•cm has not been routinely achieved with earlier generation EVA-encapsulants. New-generation EVA formulations are described here with volume resistivity above 1015 ohm•cm that offer improved PID resistance for PV modules. Other encapsulants based upon ethylene copolymers with high VR and lower MVTR show further improvement of resistance to PID effects. This work demonstrates that a combination of improved PV cells and high volume resistivity encapsulant is required to achieve very robust PID resistance of a PV module. |
| Databáze: | OpenAIRE |
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