This article highlights the difficulty that installers can face when choosing a suitable PV module to offer to their customers. The lack of a universal test of panel quality remains an issue. The range in quality that exists out in the market is truly astonishing. Many of the lower quality manufacturers have exited the market in recent years but there are still many still operating which remains a concern. I know when I used to work for a PV installer, I would come across many a PV module datasheet claiming dubious 25 year performance guarantees. Installers must make sure they do their due diligence when selecting their product offering for their clients. With panel prices plummeting recently, the gap in price between tier one and tier three is that much smaller now. Is compromising on the quality really worth the small financial gain?
One of the leaders in independent testing is DNV-GL, and its “PV Module Reliability Scorecard Report 2016” provides illuminating reading for anyone interested in product longevity. DNV-GL’s report summarises the various studies on panel degradation rates, and provides a great summary illustration on the many ways which panels can fail or wear out, shown below. The report highlights an NREL study that shows the median panel degradation rate is 0.4-0.5%/year for high quality panels, but 0.9-1.0%/year for all panels tested. Solar panels are commonly sold as having a 25+ year performance warranty and a 10+ year product warranty. But considering “85% of the 234 GW of installed global PV capacity has been in the field for less than five years” how confident can you be that the solar panels you’re buying (or selling) will last the distance? – DNV-GL