SolarCity said today that it has acquired the residential solar business from GroSolar, giving it presence in four states in the eastern U.S.

Through the move, SolarCity will offer its solar panel leasing program to homeowners in New Jersey, New York, Massachusetts, and Pennsylvania starting March 1, said SolarCity CEO Lyndon Rive.

Financial terms for the cash deal were not disclosed. GroSolar will continue to operate its distribution business and installation for commercial customers.

The deal adds about 55 people to SolarCity, giving it about 1,100 employees. It now works in 10 states, including California, Arizona, Colorado, and Texas, giving it the largest footprint in its line of business, according to the company.

SolarCity is a pioneer in solar financing, through which consumers avoid the upfront cost of buying solar photovoltaic panels. The model initially took hold in California and is spreading to other states, particularly in places with high electricity prices or policies to encourage solar power.

With a solar lease, consumers have solar electric panels installed and pay a monthly fee. Between reduced electricity consumption from the grid and the leasing fee, the net result is about a 10 percent reduction in electricity bills, Rive said. SolarCity also bought an energy efficiency company and intends to offer residential efficiency services in the new states later this year.

Although not a giant acquisition, it does point to a trend of consolidation among solar installers. Whereas many residential installers have historically been small operations, Rive expects that larger companies will be able to operate with lower costs and expand further.