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Daox 08-10-09 08:39 AM

Inexpensive solar garage heater
I do a lot in my garage, and I love it. But, in the winter, it really is a pain when I have to get all bundled up and go out into the freezing garage and try to do some work. So, the solution I'd like to get some input on is how to heat the garage with solar power. It doesn't have to do a ton of heating, but it does have to be kept pretty cheap.

The first thing I was thinking of was a hot air panel. Very cheap, pretty easy to make. The down side is there is no thermal mass to them. You get what you get during the day and it is gone as soon as the sun stops hitting the panels.

The second idea is a really stripped down solar hot water collector idea. The system basically consists of two 55 gallon barrels. One outside, one inside. Get an inexpensive ac or dc pump (Gary on has been using a $55 pump successfully for a year now) , a small solar panel, and maybe a DIY temperature differential controller (pretty easy to make I'd think from an arduino). The outside barrel could be enclosed in something for some insulation and freeze protection. As it heats up, it pumps the water/antifreeze solution into the barrel inside the garage. Pretty simple, and much more thermal mass. This idea could really be ramped up with a simple and nice solar collector, possibly with a small drain back system to eliminate freezing. But, this all increases cost, barrels are cheap. We'd have to see how far my budget would allow this to go.

Other ideas? I'd love to get some input.

Daox 08-10-09 09:00 AM

This is the pump Gary has used.

Swiftech MCP350 12 VDC Pump

You can pick it up on for $55.

Daox 08-10-09 09:47 AM

Another idea I just had. I have a used radiator laying around from a car. Surface area wise it is probably similar to a 55 gallon barrel. It would definitely take less material to enclose, and would be easier to mount for a drain back system.

truckncycle 08-10-09 02:14 PM

Does your garage have any windows? You could try reflecting the sunlight on to the floor and using it as a thermal mass. Although it does get cold enough here (high 20s) to wear a jacket in the garage, the bigger problem that I have is cooling. I would love an air conditioned garage. Our water heater and our car engines both provide some waste heat for the garage.

I was thinking about your radiator idea. One thought that I had is you could put the radiator inside with a fan and then treat it more as a forced air system. In the summer, you could add another radiator outside and cover it with cloth. Add a constant drip to the cloth an basically make a swamp cooler. WI may not be dry enough though.

I am assuming that your garage is already well insulated.

Daox 08-11-09 10:40 AM

The garage has two windows on the west facing side. They're not real big. Just your typical garage windows.

A radiator of some sort would be a nice thing to get more heat out of the barrel and into the garage. I'm sure I could figure something out that would do the same thing.

The swamp cooler thing unfortunately wouldn't work all that great up here. As you mentioned, its just too humid here.

The garage is not insulated as of yet, but that is something I am looking into as well. Obviously this would be the first step. With it insulated, I probably won't need a ton of additional heat. It doesn't have to be tropical, just some what comfortable to work in.

Daox 08-12-09 08:06 AM

Bumping for more suggestions. I want to hear some crazy ideas. :)

truckncycle 08-12-09 02:52 PM

You said you wanted crazy.

Move your compost bin into the garage and let the heat warm your garage.

One of the earth ships that I saw in a magazine as a kid had water drums in the wall. During the day, the outer wall was tilted down. The outer wall had foil on the inside of the insulation. The sun reflected off of the tilted wall and heated the water drums. At night the wall was closed and the thermal mass of the water kept the house warm.

Daox 08-12-09 03:35 PM

Not bad. I kinda like that! Foil mounted to a board would be a cheap and easy way of increasing collector surface area...

GaryGary 08-16-09 12:35 PM

If you main garage door faces south, you could use this scheme:
Solar Workshop or Studio

It really works well -- provides both great heat and light. Its my all time favorite solar project.
You can work the thermal mass some by placing some water filled barrels in the opening where they will get some sun exposure. I logged some temperatures with a couple barrels, and could see difference -- I think the plot is in the article. It might take more like 4 to 6 to get the kind of temperature swing you want.

Where is the southern exposure that you have to work with relative to the garage you want to heat?


Daox 08-16-09 03:53 PM

I love that simple setup too Gary. Unfortunately, the garage door is not facing south. The main garage door faces east (towards the bottom of the picture).

The other thing I have to contend with is afternoon sunlight. The house will block a lot of sun come afternoon. I haven't done any analysis to see at what time the sun stops hitting the southern wall of the garage.

On the up side, I just got back from the local electric vehicle build day. One of the guys there is a recycler and just got a truck load of thermal pane windows that someone was scrapping. I got 16 windows total, so I have some nice glass for projects (or window replacement, I only have single panes upstairs).

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