Cogenra Solar’s recently installed solar arrays at a northern California winery not only generate electricity but also heats water. The arrays combine conventional photovoltaic solar cells with a system for collecting waste heat. Several parabolic dishes, each 10 meters long and three meters wide and lined with mirrors have been installed at the winery.
The parabolic dishes are supported by mechanical arms that move them to follow the sun. It concentrates sunlight onto two strips of monocrystalline silicon solar cells suspended above. Heat is collected with a mixture of glycol and water that flows through an aluminum pipe behind the solar cells. The glycol solution is fed into a heat exchanger, where it heats up water. The water is then pumped to a storage tank, and the cooled glycol solution is fed back to the solar arrays.
This initiative is viewed as an important move in the area of hybrid solar technology. Similar hybrid solar systems have failed in the past because the solar cells have overheated. Cogenra uses sensors and automated control system to overcome this. The start up plans to install these hybrid solar arrays at businesses that use large quantities of electricity and water, and then charge them for supplying both.
The solar arrays will be able to produce 50 kilowatts of electricity, and the equivalent of 222 kilowatts of thermal energy. This will cut the winery’s use of natural gas for water heating by 45 to 50 percent, and meet about 10 percent of its electricity needs. Khosla Ventures has invested $10.5 million in the project, which is though cost-effective. Cogenra also eyes government rebates to meet the expense.
(Via Technology Review)