If a farm has a crop dryer already in place, it may make sense to install a low-cost solar heater to supplement a propane or oil heater. The farmer would save on fuel costs while still being able to dry crops in cloudy weather. The sun is a reliable source of heat, light,and power for greenhouses. National Renewable Energy Lab Greenhouse Heating Commercial greenhouses often rely on the sun for lighting, but on gas or oil heaters to maintain constant temperatures. A solar greenhouse uses building materials to collect and store solar energy as heat.
Insulation retains the heat for use during the night and on cloudy days.
To capture the most sunlight, a solar greenhouse generally faces south, while its northern side is well insulated, with few or no windows. A gas or oil heater may be used as a backup. Remote Electricity Supply Solar power charges an electric fence on this Colorado ranch. National Renewable Energy Lab Sunlight can also generate electricity. And, because they require no fuel and have no moving parts, they are more convenient to operate and maintain than diesel or gasoline generators.