Solar panels generate electricity using rays of light from the Sun – not its heat. But when they become too hot, their efficiency falls. This is because heat excites the panel"s electrons, which convert energy from the Sun into electricity, making the difference between the high energy and rest state smaller, which in turn decreases the voltage and the amount of electricity generated. Solar PV panels typically operate at peak efficiency between 15C and 35C (59F and 95F), but they can get as hot as 65C (149F), hindering efficiency.