Far Niente Winery’s Floating Solar Experiment

Posted on: October 19th, 2013 by Stas

Far Niente Winery’s Floating Solar Experiment

By Stas Margaronis

In September, Sonoma County Board of Supervisors developed new land use requirements on Sonoma agricultural producers’ ability to build solar and other renewable energy projects. Robert Andersson, executive director of United Winegrowers, representing 200 wineries and vineyards in Sonoma County, called the new rules overly restrictive and said the new rules “did not take into account that growers have some unusable land that might be set aside for renewable energy development.”

In the aftermath of the Supervisors establishing a new energy agency, Sonoma Clean Power, Andersson said the new rules made it harder for Sonoma growers to generate renewable energy locally.

In adjoining Napa County, Greg Allen, President and Wine Maker Dolce Winery in Oakville, California spearheaded the development of a floating solar system erected on the winery’s irrigation pond. The project has made the winery self-sufficient with renewable energy and minimizes vineyard land taken up by solar panels. Allen believes his winery’s experiment will provide an alternative for vineyards and growers to build solar systems that will minimize the land use impact. Allen also believes the floating system reduces evaporation by shielding the water from the sun and thus reduces the risk of the irrigation pond running low or dry.

RBTUS interviewed Allen to discuss Far Niente’s floating solar or “flotovoltaic” system:

RBTUS: Why did you decide to invest in solar energy for your winery?

ALLEN: The Far Niente Winery and Nickel & Nickel Wineries are two of four wineries in a closely held partnership, along with the Dolce and EnRoute Wineries.   Back in 2006, we were looking at a way to eliminate the cost of our electrical bills at Far Niente and Nickel & Nickel, which together ran within the range of $250,000 to $275,000 per year based on an annual consumption of 1.5 million kilowatt-hours (kWh).

RBTUS: How did you decide on developing a floating solar system?

ALLEN: Our goal was to offset 100% of the electricity costs with renewable energy generation.  We discovered that 4,200 panels would be required to accomplish this goal and that two-and-a-half acres of land would be required to accommodate these panels.  We were looking for a solar solution that would not be piecemeal like putting some panels on car ports and some on barn roofs scattered about the property but rather something that would look purposeful and organized.  This much land, however, constituted a significant opportunity cost in terms of its viticultural value in annual grape production, so we focused on solutions that would minimize the amount of grapevine removal yet still meet our goals for energy production.  Clearly, the pond would provide the solution.

RBTUS: How did you select the solar provider?

ALLEN: With our designers and engineers we penciled out a few solar system designs.  But, since we were not qualified to design and build this kind of work ourselves we issued an RFP (request For Proposal) and eventually SPG Solar won the bid. It turns out they already had a plan that they had developed for a floating solar panel system.

RBTUS: You connected your pond system to a land system to develop sufficient power for Far Niente’s needs?

ALLEN: At Far Niente we decided to put panels on the pond as well as convert one and a quarter acres of vineyard to solar panels.  In so doing we were able to meet our goals for energy production.   For the floating array, SPG installed the solar panels on a pontoon structure consisting of many repeated units.  Each unit was composed of two 18 inch plastic pipes that had been filled with Styrofoam to provide buoyancy and connected them with a series of steel angle sections that supported eight panels and that also allowed for a gang plank so that you would be able to perform maintenance.

The pond and land systems are integrated so that all the panels are oriented in the same direction.  This assures a uniform power production as every panel receives the same amount of solar irradiation.  Consequently, this arrangement of panels also offers a desirable aesthetic look which preserves the naturally beautiful aspect of the vineyards.  There are 2,296 panels, 994 of which are floating on the pond, all organized into 164 strings of 14 panels. We had SPG attach various monitoring systems so we can keep track of the power production of the entire solar array as well as that for each individual string of panels.  We felt that monitoring at the string level was important for troubleshooting.

RBTUS: Can you discuss how much this cost and how long it will take for the savings to repay Far Niente’s investment?

ALLEN: The installation of 2,296 panels at Far Niente and the 1,904 panels at Nickel & Nickel cost us about $7.1M in 2006. This includes SPG’s contracts as well as costs associated with other contractors, consultants, and materials required to complete the job.  The net cost to us was substantially less, however, as PG&E’s rebate incentive program returned $2M in cash to us as well as the non-cash benefits of a federal tax credit and accelerated depreciation.  The future cost of energy is the biggest variable in determining payback;  given a conservative range of future peak and off-peak costs I estimated the payback to be between 12 and 15 years.  We are on track.  There maintenance costs are not a huge concern for us, though the floating panels have a slightly higher cost associated with them.  Notably, we have replaced about 10 leaking pontoons (not for serious structural concerns, but rather for maintaining the aesthetic of having reasonably level panels on the water).  The panel cleaning costs, which are the greatest maintenance expense we have incurred, are identical between land and floating panels.




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