Can wiring solar panels in series cause overheating?

Electrical Resistance and Overheating

When solar panels are wired in series, the voltage across each panel increases, but the current remains the same. This setup can lead to increased electrical resistance, especially if the panels are of different types or have varying efficiencies. As a result, more power is converted into heat, rather than being used to generate electricity. For example, if two 100W panels are wired in series, and each panel has a maximum power temperature coefficient of 0.05%/°C, the combined temperature coefficient would be 0.1%/°C. This means that for every degree Celsius increase in temperature, the power output of the combined system would decrease by 0.1%.

Thermal Management Considerations

To mitigate the effects of overheating when wiring solar panels in series, it’s essential to consider thermal management techniques. One approach is to use panels with higher efficiency ratings, which can help minimize the impact of increased electrical resistance. Another strategy is to implement a derating formula to account for the increased temperature coefficient of the series-connected system. For instance, if the system’s maximum temperature is expected to be 45°C, and the panels have a derating factor of 0.8/°C, the system should be derated by 36% (0.8 x 45) to ensure safe operation.