Potential seen in floating ?solar for wine and ag

Sonoma County clean energy and water officials have set up talks with vineyard, farm, dairy and other landowners in Sonoma Valley and around Healdsburg about using their irrigation ponds for what is said to be the largest floating solar-electricity project in the U.S. and the second-largest in the world.

Sonoma Clean Power and Sonoma County Water Agency plan to hold additional information sessions throughout the county over the next three months to assess landowner interest in adopting a solar-over-water option. This comes after Sonoma Clean Power signed an agreement with San Francisco-based Pristine Sun in late February to install a 12.5-megawatt solar farm on pontoon docks at six holding ponds operated by the water agency in northwest Santa Rosa and Sonoma Valley. The power agency had reviewed bids from four solar providers.

The sunset of rooftop solar is not over the horizon, but the dawn of a new application for photovoltaic panels installed as floating arrays is an emerging trend in the industry. Some have already been placed above vineyard irrigation and frost prevention ponds as well as on fully treated wastewater reservoirs. The largest floating solar array in the world is a 13.4-megawatt installation by Kyocera TCL Solar on Yamakura Dam reservoir near Tokyo.

“We took extra care to protect customers who will become involved in these floating solar installations with the risks being borne by the developer,” said Geof Syphers, CEO of Sonoma Clean Power.

The risks mainly are over project location, he said. Since the project is not typical and is over water, there are potentially increased risks associated with construction and maintenance. As a result, the power agency took special care to ensure the developer carries all those risks.

About 25 percent of all vineyards in the county have holding ponds. One hundred of these vineyards have ponds that may be suitable for floating solar arrays, and 20 to 40 are near power transmission lines. A limiting factor for site selection is a pond within about a quarter-mile of a power-transmission line to save the cost of additional poles to reach the grid.

He said the power agency provides more solar power per capita than anywhere else in the country.

“Customers have rates competitive with those of PG&E today with savings of from 6 percent to 9 percent on the entire monthly bill,” Syphers said. “Low-income customers, who qualify for a subsidy, can save as much as 10 percent to 14 percent. In the first year of operations, SCP customers saved $6 million over what they would have paid to PG&E.”

He said by 2016, with new power sources, such as floating solar farms, the power agency’s Evergreen Premium rate plan at 3.5 cents per hour could go down to 3 cents per hour for all-renewable power.

Sonoma Clean Power did not provide cost figures or details of the 25-year power-purchase agreement with Pristine Sun, but said they are comparable to contracts it has for a 70-megawatt solar energy system at a site in the Central Valley, minus the high cost of distributed generation that can be avoided by not building additional transmission lines in remote areas.

“Floating solar is a win-win for everyone involved and gives us another way to achieve SCP’s goal of continuing to find new local energy sources to produce clean and affordable power,” Syphers added. “We are also exploring the use of small scale biomass, wind power and other ways to produce green energy locally.”

When installed on land or on ponds, solar systems supply all or a portion of the electricity needs of the landowner with excess power not used being fed back into the grid.

This grid feed-back process is called “net metering” because the meter will “run backward” to provide a credit against what is consumed at night or other periods when landowner use exceeds the system’s output.

“The SCP–SCWA project is in final design and permitting stages with construction scheduled to begin in early 2016,” said water agency Deputy Chief Engineer Cordel Stillman, who is the person responsible for initiating a floating solar renaissance in Sonoma County. “Completion is expected by the end of next year.”

Stillman reintroduced the idea to local water and power officials and including it in new water project requests for proposals. When completed, this initial project will provide enough electricity to power 3,000 homes.

“There are several advantages associated with building solar arrays over water,” Stillman said.

First, pond sites are already considered to be “disturbed” and are permitted, meaning that there are no major California Environmental Quality Act issues, he said. Second, land is not taken out of production, preserving the ground for agriculture and open space.

“Aesthetically speaking, these pond arrays are usually behind embankments so people can’t see them,” he said.

Third, if the array covers less than half the pond it is thought to have minimal effect on waterfowl. That means permits can be issued over the county Permit & Resource Management Department counter. If more than half the pond is covered, steps can be taken to mitigate impact on wildlife, Stillman noted.

Studies show that solar panels over water can also reduce evaporation by 70 percent to 90 percent - a big plus during a drought - and limit algae growth, along with less use of chemicals to control it, he said. Water also cools the panels enabling them to generate more energy.

In 2008, Napa Valley’s Far Niente Winery received the world’s first floating array, a 130-pontoon platform floating on a 1.3-acre pond in the Martin Stelling Vineyard, according to President and CEO Larry Maguire. Some of the nearly 1,000 panels in the array were placed on adjacent land.

This pioneering system, developed by Petaluma-based SPG Solar and sister company Thompson Technology Industries, produces 400 kilowatts of power at peak output. That’s enough to offset all the energy needs of the winery - and then some. Missouri-based Sun Edison purchased most of the assets of SPG Solar in mid-December for an undisclosed price, according to a notice on SPG Solar’s website.

“From the moment we conceived of our Floatovoltaic grid-connected solar system, we hoped it would be something the world would want to adopt,” Maguire said. “Now, after seven years, this idea is finally beginning to take hold.”

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