Making a small solar collector

[DennisCA]

Been meaning to build one of these for a while to reduce my heating costs for the garage. I have used almost entirely surplus material, things I had to buy was the polycarbonate window for 10 euros and a fan for 25 euros, I basically have the remaining material from before.

Started with the frame for the window, as I would size the rest of the collector after that:

Then the frame, surplus paneling from the house & garage construction.

Some insulation that was left over, I will add more in the back of the collector to insulate against the wall too:

Assembled and mounted on the wall. I have painted the inside matte black. The outlet and inlet are in the lower left and upper right corners respectively.

The window frame is attached with hinges and locks, also added weather stripping to seal it up. There is a subframe with a mesh inside the collector that the air will pass through.

Then I started on the electronics, an old 230v -> 12v 1amp power supply and a cheap temperature controller from ebay, I will set it up so the fan starts once the temperature in the collector goes high enough, currently I have it set to 35 degrees.

Next step is to install the pipes and also to seal up everything with the polyurethane foam.

Fan installed in the lower port:

I made a box for this filter I have so I wouldn't pull dirty air into the collector:

Filter box mounted around the intake:

What it looks like now:

Now I have to wait and see if it makes a difference, it is a bit on the small side and the design can be optimized further yet. I only intend for this to provide additional heat when the sun shines. Hopefully the end result will be a lower electricity bill.

 

[Monkey Mark]

No idea what it does, but it certainly looks interesting.

 

[DennisCA]

Solar collector? Doesn't that say it all?

 

[clk230]

I must admit I'm a little confused , is there a solar panel or are you just hoping to warm the air in the panel then pull the warm air into the workshop .

 

[DennisCA]

I'm sorry I thought this was a common thing, but perhaps it's just in the nordics these are common. It's an air solar heater so it heats the air. There's a mesh that air passes through which improves the efficiency of the collector. It's meant to supply additional heat for my workshop when the sun shines in the colder months of the year.

 

[Monkey Mark]

Solar collector? Doesn't that say it all?

No.

I guessed it was something like that, but I've never seen them quite like that. Usual ones I see heat water opposed to air.

 

[DennisCA]

Well I've been using this only to heat my shop with and the collector puts out a steady stream of 16C air all day long, shop was 11C in the morning and around 15C+ after a few hours and remained thereabouts.

I use a powerful fan that can replace all the air in my shop several times an hour. Weaker fan would result in higher temperatures but heating a smaller volume of air. It's better to heat lots of air a little than vice versa though, more effective.

I've got several ideas for improving this collector, well building a new and bigger one next year anyway. but it looks like real success so far to me.

 

[dzj]

Interesting project!
Please keep us informed how the system functions in the winter months.
I've been thinking about building something like this and first hand experience would be welcomed.
Thanks.

 

[DennisCA]

Well a first recommendation is build it bigger, twice the surface area. I will have use of this this year I can tell, but I could get so much more out of it if I had made it bigger.

 

[DennisCA]

Been below 0 every day the last week except today, often -5 or so in the mornings, temperature at it's lowest in the shop has been 7.5C when I've checked in the evenings after work, usually around 9C now. If I had a proper logger I could see how much it drops during the night.

 

[dzj]

That's impressive!
How large is your shop?
I was thinking of a roof mounted version. Would the snow melt and fall off it or would I have to remove it?

 

[DennisCA]

I think I misspoke now that I see what I wrote....

It's been -5c or so in the mornings and nights, daytime it's usually risen to 4-9C outside, so it hasn't been below freezing all the time. So perhaps not as impressive as I first made it sound! My shop is around 28-30m2.

A roof mounted version would be inferior for adding heat in winter. The sun in winter time comes not from above but from the side, so putting a solar catcher on a south facing wall is much more effective than on the roof. A summer heater should be placed on the roof at a suitable incline though.

This effect of the sun coming from the side might be less extreme in the UK, but worth a check, where's the sun in the sky?