Influences of lamination condition on device durability for EVA-encapsulated PV modules

PV modules rely on their encapsulation to provide durability. The pottant is predominantly ethylene vinyl acetate (EVA). It is protected by foils and glass to minimise encapsulant related degradations such as delamination, decomposition and corrosion. Types of EVA and/or backsheet will influence overall durability, as has been reported frequently. The lamination process as well as material handling also contributes to overall durability, but the impact is not always obvious. This paper investigates the effect of lamination temperature on encapsulation quality and its impact on module durability in accelerated ageing tests. A series of laminations is carried out at different conditions within the typical window suggested by the manufacturer as well as slightly off specifications as could occur due to insufficient temperature control. The samples were exposed to prolonged standard ageing tests for up to 7000 hours. Use of subtractive electroluminescence (EL) images demonstrates a minimum of two different ageing mechanisms are active at different time constants and of different activation energies (Ea).