Running a conventional mini-fridge on solar power

[Mike Lewis]

Background -- A few weeks ago I broke my trailer's refrigerator. I have a Coleman thermoelectric cooler and used it as a substitute for a while. It worked surprisingly well, but it drew too much power at a constant six amp draw when boondocking. I have three roof-mounted solar panels totaling 355W of power, the dual 6V batteries, and the 1500W inverter in my trailer.

I'm still on the road, and recently it crossed my mind that I might be able to run one of those mini-refrigerators via the panels, batteries, and inverter. My thinking was that the mini-fridge's compressor would draw several amps, but it wouldn't be continuous since it turns on and off. And I need one of those things at home anyway.

So I bought a Magic Chef mini-fridge at a Home Depot and parked the trailer at a site without hookups in a state park. I ran the fridge for five days on the inverter. It worked, or almost-- when the batteries would get low at night the inverter would beep once when the fridge's compressor kicked on. Since this was in the pre-dawn hours, it was annoying. My batteries' charge ranged from 87% down to 50% during this time. The weather was mostly scattered clouds, but I had one day of intermittent thunderstorms.

I used the microwave a few minutes per day, and used the furnace at night. I noticed that turning the furnace down to 60 F made a significant difference in the batteries' charge in the morning. I also made it a point to stay away from the trailer during the day, to keep from drawing power.

My conclusion is that this scheme is practical, but just barely so. A more efficient solar controller would probably help.