Rooftop solar panels are proving profitable when homeowners sell, according to a recent study from the Lawrence Berkley National Laboratory.

Researchers evaluated 1,894 sales of California homes that featured rooftop solar arrays between 2000 and 2009 and compared them with 70,425 sales of homes without solar arrays.

On average, homebuyers paid an extra $24,705 for homes with rooftop solar arrays, according to the study titled “Exploring California PV Home Premiums.”