Published: May 25, 2016


A small solar array on a lake in Thailand. Uwe Schwarzbach

By Kate Zerrenner

With drought becoming the new normal in some parts of the country, an emerging technology brings an unexpected ray of hope: floatovoltaics.

Solar panels floating on ponds and other bodies of water are getting praise in California, New Jersey and far-flung countries such as England, India and Japan, which are all investing in such projects.

But these panels also reduce evaporation, a key concern in areas suffering from water shortages. In return, the water keeps the panels cool, which makes them more efficient.

That makes floating solar arrays an energy-water win-win – and we could use more of those nowadays.

Wine growers: Where to put panels?

California wine counties Napa and Sonoma both have floatovoltaic systems underway – one of which will be the second largest in the world so far.

The region’s rolling hills and famous historic sites attract tourists from around the world. California grapevines also sit on some of the most expensive land in the United States, so the idea of clearing out fields for large solar arrays didn’t excite local growers.

In 2008, the Far Niente winery in Napa instead installed a solar energy system on its pond. The panels have reduced evaporation from this pond by 70 percent, while generating enough power to completely offset the winery’s annual use.

Meanwhile, Sonoma County’s installation of floating panels on a series of wastewater treatment ponds is due to come online this year. It will have the capacity to power 3,000 homes.

The state’s clean energy subsidies and incentives, pressure from the ongoing drought, and an innovative tech sector have all helped the technology gain a foothold. Look for more systems to come online in California in the years ahead – and other dry and sunny states may want to follow suit. 

Huge projects launching in Asia

The largest floating solar plant in the world is underway at the Yamakura Dam near Tokyo. The plant’s developer says it will generate enough electricity to power nearly 5,000 households, while offsetting more than 8,000 tons of carbon-dioxide emissions annually.

That’s an impressive generating capacity, especially considering Japan’s acute energy-demand crisis; in 2015, the country only produced about 10 percent of its own energy. The densely populated island nation must also conserve water while taking advantage of unused space, so capitalizing on the reservoir makes a lot of sense.

And in India, a country struggling to meet the freshwater needs of 1.2 billion people, reducing evaporation in waterways and lakes is critical. Work is now underway on the country’s largest floatovoltaic project on Loktak Lake, the biggest freshwater lake in the northeastern state of Manipur.

India is not alone. A recent World Bank report estimates that water shortages could cost some regions 6 percent of their gross domestic product by 2050.

So as water conservation climbs on many countries’ agendas and the price of solar panels continues to drop, it’s natural for new and symbiotic solutions such as floatovoltaics to crop up. All we must do is think outside the box.