Renewable energy has notched a small victory in Texas, with SolarCity (NASDAQ:SCTY.DL) at the forefront of the effort. The company announced that it has signed an agreement by which it will offer its products for every new residence built by CastleRock Communities, a privately held home builder headquartered in the state. The deal covers 42 of CastleRock's communities in the Austin, Houston, and San Antonio metropolitan areas. The terms of the arrangement were not disclosed.

For owners of new CastleRock residences less than 2,500 square feet in size, a four-kilowatt SolarCity array will be their solar option. Larger homes can be outfitted with a six-kilowatt system. The latter company will install the equipment for free, and the cost of the solar electricity will be bundled into the customer's mortgage payments.

Although SolarCity has been an active company of late, completing an innovative round of financing and inking an electric car recharge deal with carmaker BMW, its stock has dropped from the lofty highs of recent weeks. On Friday, it closed at $46.59 per share, down nearly $20 from its year-to-date peak of $65.30.