Orange County Branch Newsletter

July/August 2016

Sustainability Committee

Floating Solar Panels Save Water in Drought-stricken California

By Janet Fordunski, PE  |  RMC Water and Environment

Solar panels are evolving from land installations to a new environment on the water. Floating solar panels reduce evaporation and improve water quality. These benefits are being harnessed in drought-stricken California, where floating solar panels, or “floatovoltaics,” are being installed on reservoirs and ponds in California’s wine country. For projects where rooftop installations are not feasible and land prices are at a premium, floating solar panels can be the perfect solution for green energy production.

In the warmer parts of California, lakes lose between 70 – 90 inches (6 - 8 feet) of water annually from evaporation. Floating solar panels have been shown to reduce lake evaporation by up to 70%, which can mean big water savings. In a 3-acre lake, installing floating solar panels can save 4 million gallons per year by reducing evaporation. The shade produced by the solar panels also benefits water quality by reducing algae growth and could potentially be used to minimize the formation of bromate in drinking water reservoirs. Could floating solar become the new “shade balls” for California water agencies?

For future large solar projects, water installations may be the solution. One criticism of large land-based solar projects in California is that they encroach on open space, agriculture and sensitive habitat. Across California there are many acres available on lakes, reservoirs and water treatment facilities. There are over 1,400 irrigation storage ponds in Sonoma County alone. With the added benefit of 70% water savings, floating solar panels provide another option for protecting California’s water resources and preserving open space.

California produces about half of the solar power in the United States. In July 2016, solar production by the California Independent System Operator (ISO) hit a new record of 8,030 MW. Solar power and other renewables such as wind, geothermal, and hydropower contribute nearly 30% of the electricity demands in the summer. Peak solar power production occurs during hot summer days and is an important addition to the overall renewable energy portfolio in California.

Keep reading for more details on floating solar panel projects in Napa and Sonoma Counties.

At the Far Niente winery in Napa County, a combined 477 kilowatt land and floating solar system has been running successfully for over three years. The portion of the system located on the retention pond (at top of photo) has reduced evaporation by 70 percent.

Sonoma Clean Power recently announced construction of the largest floating solar project in the United States. With 12.5-megawatt production, the Sonoma County project will produce enough electricity to power 3,000 homes. The developer, San Francisco-based Pristine Sun, is leasing the space over six recycled water ponds operated by the Sonoma County Water Agency for about $30,000 per year, significantly less than the cost of leasing land. Solar panels will be installed on floating docks to prevent them from touching the water.