Solar Energy That Floats on Water

Generating energy from the sun would be more practical if not for two huge drawbacks: The expense of the silicon material that converts light to electricity, and the large tracts of land needed for solar farms.

By solving both problems - and introducing unexpected side benefits, too - Solaris Synergy captured first place in the Israel National Cleantech Open IDEAS Competition at Tel Aviv University's Akirov Institute for Business and Environment in November of 2010.

Each Lego-like module of Solaris' Floating Concentrating Photovoltaic (F-CPV) system is faced with a curved mirrored film that clusters the sunlight into a thin line. Since only 5% of the surface needs a silicon cover, Solaris uses relatively little of the costly material. Plus, since silicon production releases contaminants into the air, using less is an environmental boon.

Sidestepping the need for large solar fields, Solaris is designed to sit on water. Constructed of lightweight plastic and fiberglass, a grid of connected modules can float on any fresh-, salt- or wastewater surface. Aside from sparing valuable real estate, this solar-on-water platform doubles as a breathable reservoir cover that significantly reduces evaporation and eliminates organic and algae growth.

To keep rays focused on the line of silicon material, the grid turns slowly as it follows the movement of the sun throughout the day. One small engine can power this rotation since the water eliminates friction. A sophisticated sun-tracking algorithm guides a remote controller, which also moderates the direction of the movement and the speed of the engine. An antenna sends all data from the controller over a cellular line to a central server and alerts the technical crew to potential problems.

Grids of F-CPV modules, each generating 200 kilowatts, can be configured to fit any reservoir, lake or pond. The system works best in areas of strong sunlight, such as Africa, Asia, Australia, Mediterranean countries and South, Central and southern North America.

Floating Solaris grids atop Israel's more than 400 recycled wastewater reservoirs would enable the country to realize its goal of generating 10 to 20% of its energy from renewable sources by 2020.

The water placement gives F-CPV another advantage via a patented technology that uses the liquid underneath to keep the silicon at a low temperature. Solaris' system is generating energy more than 20% more efficiently than conventional panels because of this. The cooler the silicon, the more efficiently it converts light into energy.

The two-year-old company has a working prototype on the roof of its headquarters and is due to install a pilot project in 2011 under the auspices of Mekorot, Israel's water authority. A second pilot installation is planned at a reservoir near Marseilles in cooperation with France's electric company, partially funded by the joint Israel-European R&D project Eureka.

Source: Israel21c