Solar panels are an assembly of connecting cells that collect photons or light from the sun to generate electricity. Damage to solar panels is caused by different factors or for different reasons. There are some common causes of solar panel damage and most of these causes damage the cells as well.

...
Solar panels are damaged for different reasons.

Hail

Solar cells have a cover made of protective glass that can be damaged by hail storms. An area that is prone to hail storms determines the kind of solar panels installed. Smaller solar cells are the best kind to install even though they are more costly. The benefit of installing smaller solar cells in areas prone to hail storms is that the cells are not as expensive to replace and less energy output is lost if damage is done to the smaller cells. Hail damage to larger solar cells results in more expensive replacement or repair costs and reduces energy output dramatically.

Water

Water is another cause of damage to a solar panel. The connections and seals around the solar panel will begin to deteriorate over time, allowing water to penetrate into the solar cells and connections. Periodically resealing the connections and protective glass will ensure that water does not penetrate into the modules causing them to fail or lose energy output. Water short-circuits the connections and moisture builds up on the solar cells limiting the energy output of the panels.

Rocks and Foreign Material

Broken or damaged solar panels can result from rocks thrown at the panels or falling debris from trees. This type of damage typically breaks the protective glass of the solar panel. Replacing the entire solar panel's protective cover and assembly is the best way to repair this damage. Just replacing the glass can cause condensation to build up inside the glass allowing moisture to get into the solar cells and connections.

Fire

Damage to solar panels can also be caused by fire. There are reports that state that some of this fire damage is caused by the solar panel itself. Individual solar panels are connected together creating a high voltage line that can exceed 400 direct current (DC) volts. These wires get worn over time, animals damage the exterior of the wires or the wires are not installed properly and this can cause the wires to short-circuit creating a fire hazard. A home or building where the solar panels are located can catch fire for other reasons and cause major damage to the solar panels.