A little-known fact about solar electric panels is that the hotter the panel itself, the less efficient it becomes. Studies have found a 0.05% efficiency loss for every degree of temperature that is increased. The reverse is true in that efficiency increases by 0.05% for every degree temperature decreases.

Although the numbers above are an average, efficiency change depends on the panel design and hardware used. The temperature coefficient is how solar panel manufacturers measure how well a panel handles heat or cold. It’s a range for the temperatures at which a panel can produce at its best.