Water barrels, typically painted black, act as a thermal mass by absorbing solar energy during the day and slowly radiating that warmth into the air at night. Another technique involves using ground-coupled heat exchange, often called earth tubes, which circulate greenhouse air. . Harnessing the sun's energy is a sustainable and cost-effective approach to managing the climate within a greenhouse, especially during colder months. And that's why we've created this guide on how to heat a greenhouse with solar panels. Choose an efficient solar collector, typically 1 sq ft per 3 sq ft of floor space. The good news is, you can prevent having high fuel bills by learning how to heat a greenhouse with solar panels! An active solar greenhouse system works by getting power from the sun and. . Aside from using the solar system to power the fans and heat the greenhouse, thermal mass in the lower part or ground of the greenhouse can regulate the cold areas and efficiently cover everything with heat.