Assessment of ageing through periodic exposure to damp heat (85°c / 85 % RH) of seven different thin-film module types

In this paper we have investigated the accelerated ageing of seven different thin-film module types through the use of sequential damp heat (85°C/85% RH) tests. The module types [a-Si, tandem a-Si/a-Si micro-morph a-Si/¿-Si, triple junction a-Si, CIS (x2) and CdTe] were selected to cover a range of thin-film devices, materials and construction types. Sequential damp heat tests for cumulative exposure times of 250, 1000, 2000 and 3000 h have been achieved to date, with the modules subjected to visual inspection, electrical insulation measurements and electrical performance measurements (IV curves). A wide range of performance losses (P_max), from almost zero to -70%, were evident for the different technologies. Sequential damp heat exposure tests can be used to induce accelerated aging on thin-film modules. However, it is not possible to equate loss of power to a number of years of outdoor exposure due to the lack of knowledge of the acceleration factors for each PV module type.