20 years of life and more: where is the end of life of a PV module?

All commercial manufacturers of photovoltaic modules define the expected lifetime of their products through guarantees of peak power rating of the module after 10 to 25 years of operation. These estimations are based on accelerated lifetime testing such as the IEC61215 and limited field experience. As the first installed systems and arrays are reaching 20 years plus lifetime we can now for the first time begin to associate the levels of accelerated testing of type approval with actual field behaviour. The paper presents some key behaviour of several different silicon technologies, dating back to 1982. The basis of the analysis is the JRC ESTI outdoor test field where examples of diverse generations of PV technology have been exposed to long-term outdoor exposure. The effect of performance degradation on the lifetime is explored in order to quantify the impact of degradation on performance. Results indicate that current module technologies may far exceed the nominal 20 years lifetime assumed in all financial calculations.