Norwegian flag in sun.Bright ideas from sunny Norway (and Seattle).Photo: Rob GloverWhen you think of solar powerhouses, Seattle and Oslo do not exactly come to mind, what with their often-gray skies and location in the northern latitudes. But both have been a hotbed of green tech innovation. Now, two solar companies from those cities have created a joint venture to build photovoltaic power plants in the western United States.

The new company, NorthLight Power, is collaboration between Summit Power, a Seattle-based solar developer, and Norway’s Renewable Energy Corporation, one of the world’s biggest photovoltaic wafer and module makers.

NorthLight already has signed a contract to supply electricity to California utility PG&E from a 60-megawatt solar farm called North Star, to be built in the state’s Central Valley west of Fresno.

The joint venture is just the latest deal between American and overseas companies to tap a booming market for photovoltaic power plants in the U.S. That market is being driven by state mandates that utilities obtain a growing percentage of their electricity from renewable sources as well as 50 percent drop in the price of photovoltaic modules over the past two years. That’s made solar increasingly competitive with fossil fuels like natural gas.

A report released by GTM Research this week found that utilities have signed contracts for 5,400 megawatts’ worth of solar farms to be built by 2014, and are in negotiations for another 10,100 megawatts. California utilities, not surprisingly, account for nearly 80 percent of those contracts.

Earlier this month, SolarReserve, a solar developer based in Santa Monica, Calif., formed a joint venture with China’s largest manufacturer of polysilicon and wafers for solar modules, GCL-Poly Energy Holdings, to build photovoltaic farms in the desert Southwest. And in September, Japanese solar panel giant Sharp acquired San Francisco’s Recurrent Energy, which develops photovoltaic power plants.

For solar module makers like REC, hooking up with a power plant developer provides another source of revenue as well as a market for its products. For the developer, a potential benefit is the ability to secure a supply of solar panels on competitive terms.

Just don’t expect to see a lot of solar farms sprouting around Seattle quite yet.