24 The Challenge with Staying off the Grid The trick is air circulation and finding the right passive fit for moving air around. It is one of the most overlooked necessities in a greenhouse because it prevents conden- sation, aids pollination, moves hot and cool air pockets, and helps to prevent infestation. The challenge in any passive greenhouse is air circulation and finding the right way to move air around. It is one of the most overlooked necessities in a greenhouse because it prevents condensation, aids pollination, moves hot and cool air pockets, and helps to prevent infestation. We are frequently asked if we sell solar powered circulating fans and unfortunately, to date, we have not found a solar powered circulating fan that is worth the financial investment. The amount of power necessary to operate a fan is pretty substantial and you would need a fairly large solar field to run it. Heating and Electrical A 4KW heater requires a 220 Volt outlet which usually means a new electrical subpanel. If you are thinking about a gas heater, it’s a good thing to bring in a gas fitter before the concrete gets poured. Many people ask where power should be brought into the greenhouse. We believe the best location is to put the electri- cal panel on either side of the door. The other benefit is that it’s right inside the door with easy access to control and switches.