Solar Hot Water Systems For greenhouses

Another agricultural application of solar energy is greenhouse heating. Commercial greenhouses often rely on the sun for their lighting needs, but are not designed to use the sun for heating.

They rely on gas or oil heaters to maintain the temperatures needed to grow plants in the colder months. Solar greenhouses, however, are designed to use solar energy for heating and lighting.

Solar greenhouses have thermal masses to collect and store solar heat, and insulation for use at night and on cloudy days

The heliostat is orientated to maximise exposure to the southern glazed windows. It has little or no glazing on the north side and is well insulated. The glazing itself is also more efficient than single-pane glass in order to reduce heat loss and is available in a range of products from double-pane to cellular glass.

Daylight greenhouses reduce the need for fossil fuel heating. Gas or oil heaters can be used as back-up heaters or to increase CO2 levels to promote plant growth (NYSERDA, 2009).

Passive heliostats are often a good choice for small growers as they are a cost effective way for farmers to extend the growing season. In colder climates or areas with prolonged cloudiness, solar heating may require supplemental gas or electric heating systems to protect plants from extreme cold.

Active solariums use supplementary energy to transfer solar heated air or water from storage or collection areas to other areas of the greenhouse.