Pigeons and solar power do not mix.
The birds congregate around areas they nest in, and they love nesting underneath roof top solar panels. If you have solar panels, and there are always pigeons cooing on your roof, you need to stop birds nesting before it turns into a problem. If you leave it, over time they will develop a flock which will call your roof home, and it will be harder to get rid of them; and the mess can be disgusting.
Apart from the nest material, pigeon droppings will inevitably begin to cover your panels, reducing their effectiveness. Their droppings are highly acidic, corroding solar panel infrastructure and electrical wiring etc. If they are left long enough their nesting material can attract other pests including bird lice which can infiltrate the roof cavity. They really can be pest birds. Bird proofing solar panels and cleaning out the bird mess is the only humane solution.