Bright, hot days and long-lit evenings are back in the Pacific Northwest until the equinox signals a return of the October cloud cover. These are the months when solar energy banks a surplus to be drawn down during the long rainy season.

Washington doesn't exactly have a reputation as a hotbed for photovoltaics, but when the sun's out it's powerful.

“We’re actually a drought-Mediterranean climate during the summertime,” said Mike Nelson, photovoltaics (PV) project director at Washington State University’s Energy Program.

On average, a one-kilowatt solar PV array in western Washington will yield about 1,000 kilowatt hours (kWh) of electricity over the course of a year, enough for a Seattle City Light customer to completely replace the amount of fossil fuel-based electricity they use, Nelson noted. While the array will produce about half of the energy used during the winter months, a south-facing array can make up to twice as much electricity as is consumed during the sunny summer months.

Nelson, who manages Washington State Univesity’s Northwest Solar Center, helped craft legislation that was recently signed into law by Gov. Christine Gregoire. Under Senate Bill 5101, homes and businesses with solar PV systems can earn up to $2,000 a year in credits at the rate of 15 cents per kWh of the electricity they generate. The credit is geared to the output of a typical 3.5 kW PV system.

The current cost of PV-produced electricity is about 18.5 cents per kWh for commercial projects, Nelson noted. By 2010, the forecast is for that rate to come down to 10 cents, dropping to 5.7 cents by 2015.

“We’ve passed some legislation that effectively reached out to 2015, grabbed the curve and dragged it back to the present,” he said. “Solar is currently cost-effective in Washington State.”

Because of the $2,000 annual cap, he said, the credit is most cost-effective for relatively small residential projects. But with some creative work it can be ramped up to be cost-effective for larger commercial applications as well, he added. 

Washington's law was the first in the nation to pay for solar energy as it is generated, instead of paying for the systems upfront, Nelson pointed out. A similar system of incentives in Germany has turned that country into one of the world’s largest markets for PV equipment. Nickerson said demand from the German and Japanese markets has led to a shortage of solar systems and a hike in prices in the United States.

Producers of solar photovoltaic modules are conspicuously absent in Washington, but other businesses in the state are involved at various points in the creation of PV systems. Arlington, in Snohomish County, is home to two manufacturers of the current inverters that turn DC power from solar arrays into usable, storable AC power— locally based Outback Power Systems and Xantrex, a Canadian firm that recently bought Trace Engineering. Shell Solar, which bought out Siemens Solar, produces the pure silicon used to build solar cells in Vancouver, Wash.

“That’s our crystal growing facility,” said Tina Nickerson, a Shell Solar spokeswoman in Southern California. “They melt the silicon down; they drop a seed, and it forms into a large ingot. Then they get shaped up there.”

The finished ingots are shipped to Camarillo, Calif., where they are cut into wafers and the photovoltaic cells are made. “We use them as fast as we can get them,” she said.

In 2003, Shell Solar provided ninety 150-watt solar panels for a 14 kW photovoltaic system placed atop the Ogden Service Center at the Washington State School for the Blind in Vancouver. In Moses Lake, the Grant County Public Utility District has added a demonstration PV system to the wall of its office building.

Some of the biggest names in solar module manufacturing were located in the Northwest at one time but have moved manufacturing operations elsewhere. RWE Schott Solar, which acquired Applied Power, used to manufacture modules in Lacey, Wash., near Olympia. RWE moved its North American manufacturing to Billerica, Mass., and recently added plants in Alzenau, Germany, and the Czech Republic.

In order to develop a market for locally produced PV arrays, SB 5101 includes multipliers for using modules produced in the state that can be added in, boosting the effective rate to more than 60 cents per kWh. What's more, SB 5111, a companion piece of legislation, provides tax incentives to support the solar panel production industry in Washington.

“Washington's climate is ripe for the solar industry, given the proper incentives,” said state Sen. Bob Morton (R‑Orient), ranking member of the Senate Water, Energy and Environment Committee. “This bill comes at a time when Washington must diversify its energy generation.”

Nelson was a bit less optimistic. “We have a little bit of hope, maybe, of playing some catch-up and getting to be a producer here, especially in the Pacific Northwest,” he said.