||Building Better Bay Area ||

Perched along the Russian River, the town of Healdsburg is best known for its excellent wine and weekend getaways. But these days, the sun does more than just ripen the grapes. It produces energy in an unusual setting.

Healdsburg has now become home to United States’ largest floating solar power project. The Healdsburg Floating Solar Project is a 4.78MW array sprawling across two wastewater treatment ponds in Sonoma County.

The project covered roughly half the combined 15 acres of ponds with the help of 11,660 bifacial modules. These are double-sided modules that allow sunlight to convert into energy from both the top and bottom. The project claims to be the country’s largest installation of its kind to date.

Installing a floating solar system in the United States is still a novel effort. The first “floatovoltaic” array in the world was installed a decade ago at a California winery. However solar systems that reside atop stagnant water still haven’t claimed a significant share of the U.S. solar market.

“In the United States, it’s been a niche application; where in other places, it’s really been a necessity,” said Jordan Macknick, the Lead Energy-Water-Land Analyst for NREL and Principal Investigator of the project that produced the paper “Floating PV: Assessing the Technical Potential of Photovoltaic Systems on Man-Made Water Bodies in the Continental U.S.” “We’re expecting it to take off in the United States, especially in areas that are land-constrained and where there’s a major conflict between solar encroaching on farmland.”

NREL released a study in 2018 that claimed if solar was installed on just a quarter of the manmade bodies of water in the United States, it would account for 10% of the country’s electricity needs.

The Healdsburg project edges just ahead of the floating solar array to have previously laid claim to the throne; a 4.4MW project completed on a retention pond in New Jersey, which was energized in late 2019.

The project achieves two objectives for the city. First, the 4.78MW project would help generate approximately 7,181 megawatt-hours (MWh) of clean energy annually. Second, the arrays help to mitigate algae growth in the pond.

Healdsburg gives the treated water away to vineyards — that’s the only permitted reuse for now, Crowley said. Preventing algae growth could allow Healdsburg to sell the recycled water to new agricultural users like fruit orchards or cattle pastures, monetizing the recycled wastewater to generate more savings for the city.

That amount of energy the Healdsburg Floating Solar PV project produces annually is enough to power roughly 1,110 California homes, which use an average of 6,471 kWh per year according to the U.S. Energy Information Administration. Floating solar farms are quickly gaining popularity in the U.S., particularly in places like Sonoma County where the price of land is dear.

“You couldn’t go out and buy a bunch of vineyard land for a solar project and make it economical,” Healdsburg utilities director Terry Crowley said. Floating solar farms are cost-effective as the price of solar panels continues to drop, and are easy to build, Crowley said.

The project brings Healdsburg a significant step closer to reaching the city’s goal of securing 60% of its energy supply from renewable sources by 2025 — a more aggressive benchmark than the state’s equivalent 2030 mandate. With the floating solar farm, 48% of Healdsburg’s electricity comes from renewable sources, Crowley said.

Like other California municipalities, including Sonoma County, Healdsburg is interested in developing microgrids — renewable energy-based electrical systems that can operate independently of the state’s utility giants.

A microgrid needs battery technology to store solar energy. While panel costs have plummeted, battery technology remains expensive. The city has no concrete plans for installation yet but would like to find a company to contract with within the next two years, Crowley said.