Feb. 18--The home solar installation market will see fewer but larger players as the pace of mergers and acquisitions accelerates, industry insiders forecast.

Wednesday, a New England solar installer announced an aggressive move into sunny California, acquiring the residential-installation portion of Borrego Solar Systems, a San Diego County company with three Northern California offices.

GroSolar, based in White River Junction, Vt., will emerge from the deal as the fourth-largest residential solar installer in the United States, and its chief executive said it hopes to rival industry leaders Solar City of Foster City, Akeena Solar of Los Gatos and REC Solar of San Luis Obispo.

"California is 70 percent of the solar market," said Jeff Wolfe, GroSolar's CEO. "We've very consciously grown our business. We wanted to be firmly established before we entered the fray here."

The move follows the recent merger of two other solar companies, Regrid Power of Campbell and Real Goods Solar of Hopland.

"The market is definitely showing signs of commoditization," said Tom McCalmont, the Regrid Power executive who is now CEO of Real Goods Solar. "This happens in all markets as they mature."

Installing rooftop solar systems continues to be a booming business in the state. Twice as many megawatts of solar power went online in 2008 as in 2007, according to a recent report by the California Public Utilities Commission.

In all, 158 megawatts

of solar power were installed in 2008, up from 78 megawatts in 2007. Since the California Solar Initiative was launched in early 2007, the state program has received 18,290 applications for solar project rebates.

GroSolar started as an installer in 1998, and began distributing panels to other installers in 2004, Wolfe said. It received venture funding in 2006, and added commercial installations to its residential and distribution business in 2008.

The company now does home solar installations in nine states and has 200 employees. It will absorb 65 workers from Borrego.

Borrego Solar Systems, based in El Cajon, will move away from residential installations to concentrate on commercial and government solar projects, which make up 75 percent of its business, CEO Mike Hall said.

"When we looked forward at how to scale the business, we needed to start thinking about megawatts, not kilowatts," Hall said.

Borrego will focus on projects generating from 200 kilowatts to 3 megawatts, with a special emphasis on schools and low-income and multiunit housing projects. It will keep a Bay Area presence, opening an office in the East Bay in the near future, Hall said.