The Kenwood Press
News: 04/01/2016

Kunde Winery first in U.S. to install Hydrelio floating solar array

Sarah C. Phelps

floating solar at Kunde winery
A Hydrelio photovoltaic system floats in the center of one of the irrigation ponds at Kunde Family Winery. Photo courtesy of Ciel & Terre International

On March 17, Kunde Family Winery became the first in Sonoma Valley to install a Hydrelio floating solar array on one of its eight irrigation ponds.

The 10KW Hydrelio photovoltaic (PV) system, installed by a team from Petaluma-based North Coast Solar, is made up of approximately 35 260-watt solar panels floating on what look like oversized plastic gas tanks. The high-grade polyethylene floats hold the solar panels at a 12 degree angle and snap together like Legos, making the system easy to assemble and also easy to expand in the future.

By installing floating solar, Kunde Winery is continuing in its long history of sustainable winemaking, said Chairman Jeff Kunde. “It’s fun and it fits into our business model,” he said. “We try to be forward thinking and think about our community. It’s a technology that may be able to eventually help homeowners in the future.”

Kunde Family Winery has long been a leader in sustainable farming and winemaking practices. It was one of the first wineries in the county to become certified sustainable by the Certified Sustainable Winegrowing Alliance, the first in the county to install a solar thermal system for its hot water, and now it’s breaking new ground using floating solar.

The Hydrelio solar technology, developed by a French company Ciel & Tierre, has several benefits over traditional land or roof-based solar installations, according to Eva Pauley-Bowles, international sales director for Ciel & Terre. Nestled in an irrigation pond like Kunde’s, there is low visual impact, especially important in a Scenic Corridor like Sonoma Valley. The system covers the water, like a pool cover, stabilizing temperature, and minimizing evaporation and algae blooms.

Floating PV systems are naturally kept cooler by the water, reducing the need for a dedicated cooling system and improving power efficiency. Kunde Winery’s system will include two monitored arrays, one floating on the pond and a more typical ground mounted array on the shore. North Coast Solar plans to compare the performance between the floating and the landlocked panels. “Our hypothesis is that those on the water will be maybe 10-20% more efficient,” said Brian Hines, president of North Coast Solar.

For those with an irrigation pond or two already, a floating system does not require excavation or the building of any new infrastructure to house panels or take up prime vineyard land, which means they can be much cheaper. The panels need cleaning only twice in the summer. “In the winter, the rain washes them for us,” said Hines.

Enphase microinverters on the back of each panel convert the DC current to AC. In addition to being hooked up to electrical service for vineyard irrigation, Hines said two of the panels operate the solar powered SUNGO aerator. “It is a very efficient motor and will improve water quality in the pond by creating circulation during the day and adding dissolved oxygen to the water,” said Hines. SUNGO aerators, supplied by Aquago, are being used in Vietnam to aerate shrimp ponds and in Europe to extend the life of wastewater lagoons. The fact that a SUNGO aerator was part of the whole package made the project particularly interesting, said Kunde.

A floating PV system is also less susceptible to damage from earthquakes, said Pauley-Bowles. Ciel & Terre has several large projects in Japan – including what’s being called the world’s largest floating solar farm – thanks to renewable energy incentives introduced following the Fukishima nuclear disaster. In a country quickly running out of land suitable for large-scale solar projects, and one notorious for seismic activity, floating solar is catching on there. Plus, the technology is drinking water compliant as the polyethylene floats are made from food-grade plastic. Hydrelio PV systems have been installed in several drinking water reservoirs in Europe. At Kunde, the pond is also a drinking water reserve.

A larger system installed on one of Kunde Winery’s other ponds could generate as much as 700KW, enough to power the entire winery and then some, noted Hines. If the recent installation proves as successful and efficient as anticipated, Kunde said he may consider installing other arrays on other ponds.

Some other wineries in the area also have installed floating solar, using a similar technology called Floatovoltaic. Gundlach Bundschu Winery and Far Niente Winery (in Oakville) installed floating solar arrays in 2008.