A hot spot is a cell in a solar panel that gets very hot because it cannot compete with the other cells that are producing power as usual. This cell then, instead of producing energy, starts to absorb energy, and therefore becomes hot. The cause dirt, shadow concentrated in one spot, microcrack(s) or a manufacturing defect. A hot spot that exists for a long time eventually causes the entire panel to fail and there is a risk of fire. Both are not desirable.
Prevention is better than cure so a quality check of the solar panels before installation is recommended. Of course, engineering without shade is desirable. But even then, the problem may arise or become significant further up in the lifetime of the solar system. To track this, Everday is working with a drone equipped with a thermo-graphic camera.
After investigation, it is clear if and if so where hotspots are present in a solar system. It is determined whether these have a direct significant effect on the yield of the system. From this follows a consideration of what measures are proportional, necessary and/or desirable. Cleaning is often not an issue; replacing panels is much more invasive. Another choice may be to monitor the system especially well and make concrete interventions at a later time. Thus, we seek the best balance between safety, production and investment.
Typical causes of hot spots are bird droppings or a fallen leaf from a tree, or the concentrated shadow from a very thin pipe on the roof, or from a sprite from lightning rods.