According to Professor Alastair Buckey of the University of Sheffield, solar panels are most efficient in the spring when the weather is cool and the skies are really clear.
The fact is that solar panels work by absorbing light energy and using that energy to “excite” electrons. An electric field is then created that allows electrons to flow electrically. The greater the light intensity, the greater the electric flow. But the hotter the panel, the more electrons are already excited before the photon strikes, reducing its efficiency.
Modern hybrid solar panels are designed to be less affected by heat, but can still lose 10% of their rated efficiency on hot days.
Source: Ferra
