JUNCTION CITY, Ore. - Sun rays hit a spread of solar panels on the winery's rooftop, and owners Robin and Danuta Pfeiffer watched as their electric meter's dial spun backward.

They were putting power back on the grid as the sun light converted to electricity and powered both the winery and the couple's home in the southern Willamette Valley.

The Pfeiffer Winery, which produces about 1,500 cases of wine each year, is one of at least five Oregon wineries to go solar.

Torri Mor Winery, Stoller Vineyards, Schafer Vineyard Cellar and Sokol Blosser Winery have also installed solar panels to power their businesses.

"We wanted to be as green as we could," Robin Pfeiffer said, "but it has to pencil out."

And it does.

While the Pfeiffer's solar project cost $216,000, the couple expects their net cost over five years to be a fraction of that.

State tax credits, which increased from 35 percent to 50 percent at the beginning of 2007, as well as federal tax credits, other tax incentives, and the ability to save on their electric bill brings the net cost of the project down to $4,600.

Pacific Continental Bank financed the project and will act as a "passthrough" agent, paying the Pfeiffers for tax credits that exceed their tax liability.

The Pfeiffers will use the money from selling the tax credits to pay their loan.

"We couldn't afford it without the tax credits," Danuta Pfeiffer said.

In 2003, 64 new residential photovoltaic projects were built; in 2007, there were 233. On the business side, the number of photovoltaic projects has increased from 29 in 2003 to 109 in 2007.

For a business that relies on harnessing the power of the sun to grow grapes, using solar power makes perfect sense, Danuta Pfeiffer said.

"Wineries are supremely set up to use solar energy," because vines grow on sun-washed, south-facing slopes, she said. "It's a natural."