Climate specific thermomechanical fatigue of flat plate photovoltaic module solder joints

• FEM simulations of PbSn solder fatigue damage are used to evaluate seven cities that represent a variety of climatic zones.
• It is shown that the rate of solder fatigue damage is not ranked with the cities' climate designations.
• For an accurate ranking, the mean max daily temp, daily temp change and number of clouding events are all required.
• A physics-based empirical equation is presented that calculates solder fatigue damage according to these 3 factors.
• An FEM comparison of solder damage accumulated through service and thermal cycling demonstrates an equivalent exposure.
• It is demonstrated that increasing the max cycle temp may reduce the number of thermal cycles required for an equivalent exposure.

FEM simulations of PbSn solder fatigue damage are used to evaluate seven cities that represent a variety of climatic zones. It is shown that the rate of solder fatigue damage is not ranked with the cities' climate designations. For an accurate ranking, the mean maximum daily temperature, daily temperature change and a characteristic of clouding events are all required. A physics-based empirical equation is presented that accurately calculates solder fatigue damage according to these three factors. An FEM comparison of solder damage accumulated through service and thermal cycling demonstrates the number of cycles required for an equivalent exposure. For an equivalent 25-year exposure, the number of thermal cycles (− 40 °C to 85 °C) required ranged from roughly 100 to 630 for the cities examined. It is demonstrated that increasing the maximum cycle temperature may significantly reduce the number of thermal cycles required for an equivalent exposure.