As homebuilders seek to stand out in a struggling housing market, more are including green features such as energy-efficient lights, appliances and windows in their standard packages. Now, there's a push to add solar panels.

KB Home, one of the largest U.S. homebuilders, has announced that it's now adding -- as a standard feature in 10 southern California communities -- a small, 1.4 kilowatt, six-panel rooftop solar array that's capable of cutting energy costs by about 30% for a 1,800- to 2,000-square-foot home. The systems are made by SunPower Corp.

"We are raising the bar even higher and taking an important step in making our homes even more efficient and affordable for our homebuyers over the long term, especially when compared to resale homes," Jeffrey Mezger, the company's president and CEO said in Tuesday's announcement. He said if consumers like it, the company will expand the solar feature to other regions.

KB Home has offered photovoltaic systems as an option in certain California and Colorado communities for years, but this is the first time, it will make them a standard feature. It's already begun doing so at developments in Eastvale (prices start at $360,000), Temecula and Chula Vista. It plans to do so at five more communities in the next 60 days and two in the fall.

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The Los Angeles-based company unveiled in February that it's also including an EPG (Energy Performance Guide) label on each of its home, which estimates monthly energy costs. PulteGroup Inc., which includes Pulte Homes, Centex and Del Webb, plans to do the same, and Meritage Homes has been marketing all its homes -- built to Energy Star standards -- with such a label since 2009.