Identification of degradation mechanisms in field-tested CdTe modules.

Abstract

Field tests and accelerated ageing tests were conducted on CdTe photovoltaic modules with Sb-based back contacts. Significant performance degradation was observed during one and a half years of outdoor exposure. Small-area samples were prepared from field tested modules and characterized with current-voltage, capacitance-voltage and resistance measurements. Results show that module performance degradation in the field can be partly attributed to a decrease in doping concentration close to the CdS/CdTe junction and an increased resistance in the transparent front contact. A comparison with results in the literature indicates that bias voltage may play a role in the degradation process.