At the National Clean Energy Summit in Las Vegas last week, Senate Majority leader Harry Reid (D-Nev.) announced that construction on the world’s first hybrid geothermal and solar power plant is underway in Nevada. The base-load power of Enel Green Power North America’s Stillwater Geothermal Plant will soon be bolstered by the peak-time power production of the 24-megawatt photovoltaic array that’s now being installed at the site in Churchill County, Nev.

The geothermal power plant is under a power-purchase agreement (PPA) with NV Energy. The contract was renegotiated to allow for the photovoltaic installation. Since it’s adjacent to the geothermal power plant, the photovoltaic array can take advantage of the same interconnection junction and transmission lines.

“The Stillwater project has not been meeting the PPA performance requirements, due to insufficient geothermal resource,” said NV Energy spokesperson Mark Severts. While geothermal power can produce continuous, base-load energy like a coal or natural-gas plant, the geothermal resource itself can lessen over time, reducing its generation output.

Once completed the project should help displace power from other fossil-fuel generating sites.

“Enel proposed adding solar photovoltaic to increase generation and meet its performance requirements,” Severts said. “NV Energy determined that the solar addition would be beneficial to our customers. NV Energy and Enel executed an amendment to the PPA to incorporate the solar addition, which was approved by [the Public Utilities Commission of Nevada] in July.”

While not common, some PPAs do allow for some changes like this, according to Severts.

“Some of our PPAs provide for the supplier to make limited adjustments—up or down—to the contractual amount,” he said. “Adjustments not provided for in the PPA would require an amendment to the PPA and would be undertaken by NV Energy only if such an amendment would be beneficial to our customers.”

Enel has developed numerous renewable energy projects around the world, including solar, wind, geothermal and hydro. But this is a first for the company.

“It’s our first solar project in the U.S.,” said an Enel spokesperson. “Bringing a solar project together with our geothermal project is a great way to bring the two renewables together. Geothermal is a base-load source. And at the same time solar is more valuable, and they kind of complement each other.”

Image courtesy of NREL.