There are three types of solar panels: Mono crystal, multi- or poly-crystalline, and amorphous silicon. Each of these solar panel types is estimated to last at least twenty-five years. Some estimate that forty years is a reasonable expectation. The longevity rating of a solar panel refers to the number of years before the unit starts producing only 80 percent of its original power rating. For instance, some solar panels are warranted to produce at least 80 percent of their full-rated power after twenty-five years. Instead of stopping production completely, a solar panel will gradually produce less and less power over decades. Mono solar panels are currently the most efficient type available, meaning that they produce the most power per square foot of module. The cells are fragile so they must be mounted in a rigid frame, and the solar panels usually have a polka dot or checkered pattern.

Multicrystalline solar panels are made of cells cut from multiple crystals that are grown together in an ingot. They are similar to single crystal cells in module structure but slightly less efficient since they require a bit more surface area to produce the same amount of electricity.