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Customer Profiles

The Art of Decanting Sunlight

July 1, 2011 by Real Goods in Customer Profiles with 1 Comment

Galileo once said, “Wine is sunlight held together by water.” Growing on a sloping plateau that rises 1,400 feet above sea level, the grapevines of Oakville Ranch — one of Napa Valley’s first vineyards — are perfectly situated to turn sunlight into wine. Now, thanks to Mary Miner, Oakville’s owner, banks of solar panels nestled amongst the vines silently turn that same sunlight into electricity to meet the vineyard’s power needs.

Oakville Vineyard manager Phil Coturri and General Manager Paula Kornell

“Going solar just made sense,” says Paula Kornell, Oakville’s general manager. “From a business point of view there’s the dollar savings, but we also farm organically, so it fits in well with Mary’s vision for the vineyard.”

In addition to farming organically and focusing on small-scale wine production, Oakville has added 18 owl-nesting boxes and raptor roosts to the vineyard’s 350 acres to encourage population growth and support biodiversity.

When Miner made the decision to go solar, she turned to Jack West, a principal engineer at High Sun Engineering, who has 20 years of experience designing large-scale solar systems. West analyzed Oakville’s billing history, ran a detailed computer simulation of various designs and then measured possible locations with a sunbath tool. After modeling the results, he worked with Oakville staff to choose the best site for the panels.

Miner chose Real Goods Solar for the installation and, according to Oakville’s staff, the six-week installation process went smoothly and didn’t interrupt day-to-day business operations. “Other than a little excitement when the installers moved the panels and discovered rattlesnakes hiding underneath them, it was stress-free,” Kornell recalls.

Inverters for Oakville Ranch's solar electric system

Real Goods Solar completed the 137kW installation — including 684 panels situated on four sites — in February 2007. According to Real Goods Solar’s VP of Commercial Sales and Installation, Roy Phillips, who worked alongside West, “It was the largest solar array in the area at that time, with five separate meters over 350 acres and special engineering structures tucked into the hillside. Jack found a clean way to make it look good.” Oakville’s PV system now runs all the electricity for the pumps, wells, Miner’s home, a garden greenhouse and a caretaker’s home. The system is very close to handling 100% of Oakville’s electrical needs, but the vineyard is currently upgrading its pipes and irrigation system, as well as relocating some low-producing vines, and Kornell is going to wait before assessing whether to add additional PV.

“It’s an old ranch. Once we streamline the irrigation system, we’ll be able to figure out our final energy needs,” Kornell explains, and adds that the goal is to make the vineyard carbon-neutral eventually, which means there’s always something to do. “We’re always trying to figure out how to improve things,” she says. “The vineyard is a constant work in progress.”


System size 




684 SunPower 215W panels

25 SPR 5200s, 2 SPR 3200s


Solar panel array at Oakville Ranch

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One Comment

  1. solar panels ukNovember 30, 2011 at 2:24 amReply

    Good information, we’ve created a small-scale guidebook to solar power systems on our blog that could be of great interest to your subscribers.

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