First Solar has acted as an engineering, procurement and construction (EPC) firm for large ground-mounted solar farms, but they have never been in the rooftop s

First Solar has acted as an engineering, procurement and construction (EPC) firm for large ground-mounted solar farms, but they have never been in the rooftop solar installation business like SolarCity. First Solar's panels would also be an unusual choice for a rooftop installation even if a different installer handled the work. Rooftop solar installations typically call for high efficiency panels. First Solar makes lower efficiency, lower cost panels that maintain performance at elevated temperatures. Their panels are good for solar farms, particularly in hot climates. They don't have anything special to recommend their use in rooftop projects.