Thermo-mechanical stresses of silicon photovoltaic modules

Modelling and analysis of the thermomechanical behaviour of silicon photovoltaic (PV) modules has been conducted using finite-element numerical methods (FEM). Experimentally determined material properties have been implemented in the model to represent the 6-cell mini-modules fabricated at the Centre for Renewable Energy Systems Technology (CREST). The stresses generated during indoor accelerated ageing tests and real outdoor conditions have been compared. It is found that the thermo-mechanical stresses are highest at the extreme temperatures during indoor testing. The outdoor accumulated stress generated within the interconnecting ribbons is greater than the stress generated during indoor thermal cycling programs for the same amount of temperature travelled. The results shed light on the relevance of indoor accelerated ageing programs to real outdoor conditions.