The three main types of solar panels are differentiated by the material used to make the solar cells. These types include monocrystalline, polycrystalline, and thin film. Monocrystalline is the most expensive option, but these panels also have the best efficiency and power output to a battery or device. Thin film panels are the most affordable, though they tend to have lower efficiency and power output than both monocrystalline and polycrystalline. Polycrystalline solar panels fall midway between monocrystalline and thin film when it comes to price, efficiency, and power output.