SolarCity has presented data and information supporting the claim that the photovoltaic (PV) modules used in its residential and commercial systems have useful lives of 35 years or longer. DNV GL, a world-renowned independent and certified third-party testing laboratory conducted accelerated stress testing at and beyond the IEC 61215 industry standard and found that power degradation of modules supplied to SolarCity by its key external suppliers is as much as 35% lower than for a comparable industry-wide selection of non-SolarCity modules, which are typically warranted for 25 years.
The greater longevity of modules fabricated for SolarCity is due to SolarCity’s stringent and industry-leading Total Quality Program, which was adopted in early 2014 and is based on similar programs in the automotive industry.
SolarCity requires its third-party suppliers to maintain effective quality assurance programs and refined manufacturing processes, and to demonstrate reliable product and manufacturing quality. Rigorous tests performed by a qualified third-party lab need to be passed on an on-going basis.