Solar-Powered Greenhouse Heating
For an industry that runs on sunlight, solar power has been a somewhat elusive development. Cees Kattenberg says Sika Energy USA has a potential solution that may interest growers. The Sikaplex Solar System uses a special curved lens in the peak of a greenhouse that concentrates light into a single line at a temperature of nearly 400 degrees. That light is focused on a water line running just beneath the lens. Water running through the line is heated to 190 degrees and stored in an insulated tank. The line is also warmed by heat rising from the greenhouse. The water can be used for heating in the winter or absorption cooling in the summer, he says.
Kattenberg says shadows aren’t a problem because the lens diffuses the light, leading to only 1 to 2 percent loss. The system works best with glass or acrylic coverings. The system costs around $200,000 per acre, but Kattenberg estimates is can provide up to 50 percent of heating costs in a cold location such as Minnesota, and the payback on the investment can come in as few as four years.