Graton wastewater district installs floating solar panels

July 3, 2023

Sonoma County now leads the nation in acres of land devoted to floating solar planels

The small town of Graton has just installed a floating solar panel array on a treated wastewater pond, a project that will save millions of dollars for ratepayers—and help the environment.

The installation by the Graton Community Services District means Sonoma County has more than 13 acres of floating solar panels, more than any other county in the nation, said Brian Hines, President of North Coast Solar, the Santa Rosa company that designed and installed the solar panel complex.

Other floating solar panel systems have been installed locally in Windsor, Healdsburg and at a Kenwood winery.

Saving ratepayers’ money is one of the District’s top priorities, said David Upchurch, president of the Community Services District Board.

 “There have been no sewer rate increases for our customers in eight years, in spite of inflation and rising electricity costs,” Upchurch said, “a trend that began when our previous president, David Clemmer, assumed office.”

“The just-completed floating solar array is but one of several projects in progress that will continue to help keep the rates stable for the foreseeable future,” Upchurch said.

The Graton project took three weeks to construct and cost $454,000. It consists of 336 solar panels resting six inches above the water on high-density polyethylene (HDPE) pontoons, custom designed by Houston-based Ciel & Terre USA.

Wastewater in the pond, the larger of two storage ponds owned by the District, is treated to tertiary levels, the highest treatment level for wastewater.

The floating solar panels are expected to save Graton ratepayers about $2.9 million in electric bills over the next 25 years. The panels produce 220,000 kWh annually –enough to serve 30 average households a year — and will reduce the district’s PG&E bills by 90 percent, Hines said.

In addition, the panels block sunlight and create shade over the wastewater pond, reducing the growth of algae, along with its attendant toxins and mosquitoes. The shaded wastewater also keeps the panels cool, allowing them to generate more electricity than land-mounted solar panels, which lose efficiency as they heat.

The project was financed through Mission Capital Solar Finance at very favorable rates. The money saved will be used to pay off the loan and to offset plant expenses, allowing customer rates to remain stable in coming years despite rising costs.