4. 1 PV Module Design, Manufacture, Performance and Reliability
Summary / Abstract:
For photovoltaics (PV) to be cost competitive with traditional energy sources, reliability is of critical importance. Historically, PV reliability has focused on the module packaging because degradation and failure modes were directly linked to the packaging. Today, in addition to module packaging, cell related reliability issues can increasingly be observed. We have investigated PV systems of high-efficiency modules such as silicon heterojunction (HJ) and passivated emitter and rear cell (PERC). System degradation of these technologies is found to be no worse than systems using conventional cell technologies. Module performance loss, for HJ and PERC technologies, shows open-circuit voltage reduction indicative of cell level changes. For HJ modules, possible hydrogen concentration changes and a rougher interface between the amorphous silicon and the silicon is observed, although more samples are needed to confirm these findings. The PERC modules show hydrogen changes in the front and rear of the cell with more changes pronounced at the front. Importantly, these two case studies demonstrate that cell level understanding is required to accurately predict module and system performance for high-efficiency technologies.