It was a long-time coming, but SolarReserve received unanimous approval from the California Public Utilities Commission for an amended power purchase agreement for its 150-megawatt solar thermal project with storage in Riverside County.

SolarReserve started work on The Rice Solar Energy Project in 2008. Issues with transmission held up development. But a new PPA with Pacific Gas and Electric was met with a lot of enthusiasm earlier this week.

There are a lot of large-scale solar projects going in throughout California right now. But this is the first project with energy storage, according to a release from SolarReserve.

The project will generate 450,000 megawatt hours of electricity, enough to power 65,000 homes during peak periods. But it will hold up to eight to 10 hours of electricity stored in molten salts for the utility to deploy when it’s most needed.

“What’s of note here, is that every single commissioner said something about the value of storage,” said Tom Georgis, vice president of business development for SolarReserve. “The issue for California and a lot of other states with heavy reliance on intermittent power generation is the continued need for power plants.”

Georgis said states like Claifornia with growing renewable energy portfolios have to keep their outdated power plants online as backup that they can fire up quickly when there are lulls in renewable generation.

SolarReserve’s system with storage can meet the demand for deployable power and genuinely replace coal-fired power plants.

“There’s no method now for quantifying the value of energy storage,” Georgis said. “It’s more expensive than standard PV, but it’s also more valuable.”

He SolarReserve is working on identifying just how valuable that storage is. If it can be quantified it could help future SolarReserve projects gain financing and utility approval more quickly and affordably.

SolarReserve is currently constructing a project in Nevada, the Crescent Dunes project, which will supply power to California. It also has started development work on two projects in Colorado.

The Rice project is expected to break ground in early 2014 and be completed in mid-2016. It will employ more than 670 worker during construction.