In June, a 1.18-MW PV system floating on a water reservoir became operational in Japan. The system called “Solar on the Water Okegawa” in Saitama prefecture is currently the biggest system of its kind in Japan. Having recognized the issues of land shortage and of protecting natural and agricultural lands, the company Ciel el Terre noticed many inland water reservoirs, which are located near grid-connection, but under-utilized.
Ciel el Terre began the R&D process for floating PV systems now marketed under “Hydrelio System.” PV modules are mounted on floats made of high-density polyethylene, which is the same durable material used in marine buoys. The Hydrelio System uses no metal parts and is as easy to assemble as LEGO blocks. Eva Pauly, International Manager at Ciel el Terre International, said that it took three weeks to assemble the floating system and three months to construct the entire Okegawa project, which consists of 4,500 PV modules.
The company conducted several durability tests to prove that the systems can withstand up to 118 mph winds and changes in water levels of up to 20 feet. In fact, the Okegawa project withstood three typhoons in Japan, according to Pauly. Ciel el Terre claims that due to the cooling effects of water, its floating PV systems generate about 10 percent more electricity than rooftop or ground-mount systems of the same size.
While this practice may seem ideal in Japan, where land is more limited that here in the States, it can still be considered a viable option compared to the popular rooftop trend that is spreading. In the U.S., there is a 190-kW (AC) floating PV system at a winery’s vineyard irrigation pond in northern California. Since March 2007, the system has been generating electricity along with a 250-kW (AC) ground mounted system installed adjacent to the pond.
While this idea is not necessarily innovating for the sustainability project, it does offer a different media to use solar panels. What is not discussed in this article, but should be discussed ethically, is the ecosystem that is disturbed by these panels. Fish and birds alike would be affected dramatically, especially if any toxic deposits somehow manage to leak into the lake. It should also be noted that the maintenance cost would be considerably more costly compared to solar panels on land due to algae removal, corrosion of panel frames, and the fact that the panels are more difficult to access.