Google will invest $300 million to help SolarCity install solar panels on 25,000 homes in the search giant’s largest renewable power deal to date, the two companies reported Thursday.

Combined with debt financing raised by SolarCity, Google’s money will form the basis of a $750 million fund to cover SolarCity’s up-front costs of installing solar arrays on customers’ homes. The San Mateo company typically leases solar arrays to its customers, who then pay monthly rather than buying the equipment outright — a model that helped revolutionize the solar industry.