More utilities are looking to build large solar power plants that can put out as much electricity as coal- or gas-fired plants, but run much cleaner.

"We're at the start of something," said Julia Judd, executive director at the Solar Electric Power Association.

Most of the buzz around solar energy has focused on smaller-scale projects, such as solar panels on rooftops. Several solar companies with highflying stocks, such as SunPower SPWR and JA Solar JASO , are in this field.

But interest is building for large, utility-scale solar projects. Such plants offer utilities a way to meet regulatory demands for more renewable energy. Governments worldwide are providing financial incentives for such projects.

"I don't think (the large projects) are a pipe dream for utility scale renewable energy," said Reese Tisdale, an analyst with Emerging Energy Research.

Larger-scale solar projects aren't new. Some of these so-called solar thermal plants were built in the 1970s and 1980s. But these projects petered out in the 1990s as the price of traditional power fell and tax incentives dried up. In the U.S., a few solar thermal plants in Southern California remain today.

Times, though, again are changing.

"You're weighing costs vs. environmental benefits," said Keely Wachs, a spokesman with Pacific Gas & Electric. "Now, natural gas prices have gone up considerably. So solar is becoming more and more cost-effective."

Essentially, solar thermal plants use mirrors to concentrate the heat of the sun on water or another liquid -- which turns to steam, and, in turn, cranks turbines to produce electricity.