You may remember from earlier posts, that we have a small shed across the driveway from the cabin where we keep our winter provisions. It has a chest freezer for meat. A second propane refrigerator for overflow from the one inside. And, this summer we installed a propane dryer for drying clothes. I worked, last summer, to get the shed insulated and critter proof, with plenty of shelves for storage. This article talks about the provisioning step.

The shed worked well throughout the winter. The heat from the propane refrigerator and full insulation helped keep it warm. Yes, there were a few times when it got very cold outside that we had a few items freeze. So, this winter, only "dry" goods and other items that can be frozen will be stored there. It would be nice to have some source of heat just for those cold days. After all, the freezer and refrigerator tend not to run when the ambient temperature is that cold, so generate no heat to warm the shed.

We have the opposite problem in summer. Even with all the insulation, the inside of the shed gets warm. Sometimes very warm. That causes the refrigerator and freezer to run more. And, the more they run, the warmer the inside of the shed becomes. And, the warmer it becomes the more they run! Thermal runaway results! We don't use the fridge for much in the summer, so I could just turn it off. But, we do use it for beer and wine.

To fix this issue (somewhat), I purchased a solar powered attic fan. It consists of a 70 watt solar panel that powers a 12 volt fan mounted in a 12" diameter housing. I replaced one of the passive vents in the shed with the fan. When the sun is shining (and likely warming the inside of the shed), the fan comes on. The fan speed varies with the intensity of the sun. The fan then pulls air through the shed, blowing the warm air outside and pulling cooler, ambient air inside.

70 watt solar panel that powers the fan.

The fan from the inside of the shed.

The fan vent cover from the outside along with the wires from the solar panel.

I haven't permanently mounted the solar panel yet. It just sits horizontal to the ground on the stack of snow tracks for the Polaris Ranger. It gets sun from first thing in the morning until late afternoon. The fan makes some noise, but I'm pretty happy with the situation. I can just unplug it for winter.