Looking for a cheap, DIY Solar Heat for my workshop

[Catweazle]

Over Christmas I built myself a new workshop in the bottom floor of a two storey outbuilding. It's 8 section breeze block, tanked with tanking slurry and polyurethane sealer on top, then 100mm expanded polystyrene insulation faced with OSB3. The insulation works well, when I walk inside in the morning it's like a fridge whilst the morning Sun is warming up everything outside.

So, it has a South facing wall that I'm wondering if I can put a solar collector / panel on. No electricity needed, just a low tech heat pump to take the chill off in the morning.

I'm thinking maybe a couple of black-painted radiators plumbed into one in the workshop.

Any ideas ?

[adam2]

Certainly possible, there are three different ways of achieving this.

1) Is a wet system whereby water is heated by a standard type of solar thermal collector and then passed through radiators in the space to be warmed. Can work well but needs electricity for a circulating pump, and will probably need filling with anti freeze.

2) Is a dry system whereby air is blown through a dry type thermal collector and into the heated space. Needs electricity for a blower, but contains no water to freeze. Needs careful design to avoid ingress of water that may freeze and break something, or prevent proper circulation of the air. Some types warm fresh outside air and blow this into the space, other take indoor air and heat it.

3) An electric system with PV modules that charge a small battery, and when this battery is full then dump the surplus into the heated space. Probably the simplest system but rather expensive. No water to freeze. The electricity can be used for lighting etc.

[BritDownUnder]

Lot's of building jargon there that I don't understand, but I do understand that you want a way of getting solar energy inside a building without electricity.

Well the easiest option is a window but I think you know that.

Otherwise, to move heat without mechanical forcing you will need to take advantage of the fact that a warm fluid nearly always is less dense than a cold fluid. Hence you will need to put your solar collector as low as possible to the ground and have the intake pipe bringing fluid into your solar collector lower than the outlet pipe taking the heated fluid out of your solar collector into your workshop.

For air heating - I have experimented with forced air solar collectors on my roof and, to be honest I found that at night condensation began to form inside, which shortly afterwards led to the heated air being very mouldy smelling warm damp air. I am sure there are ways of stopping this such as having a drain pipe at your lowest point and steep sided or vertical solar collector. The hot air could then flow through a rising pipe into the building through a hole in the wall. You could heat outside air but you could reheat air taken by a pipe from your workshop at low level.

For water heating - you might also try to experiment with a black painted radiator outside as low as possible, better still inside a glass fronted box, and pipe the heated water to a second radiator, or better still a larger water container (an old copper hot water tank for instance), that is at a higher level than the outside radiator and have a drain pipe from this indoor container that is at the lowest level possible. From experience with a wood burning system that had no circulating pump you need to have the pipes as large a bore as possible and as vertical as possible.

These are quite complex solutions for a problem that could be solved by a window but you could do things with the water tanks like insulation that could be applied when heat is not needed etc etc.

You could also try some crazy solution with mirrors to reflect heat and light into your workshop. I once read that an Italian village that was in a deep valley and never saw the sun for some part of the year did that by putting trackable mirrors to reflect sunlight down into the valley.

I did not mention electricity as Adam has done a fine job doing that in a previous post.

[adam2]

A home made solar hot air heater might be best, no water to freeze or leak.
This would need an electric fan, but the loading is modest and could be supplied directly from a small PV module.

[emordnilap]

Cat, a guy I know called Peter Crayfourd in Bolton might offer ideas, advice and parts. His website is https://solarproject.co.uk/

He's helped me out on many occasions in sorting out my SolarTwin DHW system. His business is his hobby; speak to him, he's just really happy to help people create solar systems. Great guy, very creative and knowledgeable and always interested in the cheapest solution.

[kenneal - lagger]

He repaired my Solartwin pump for me a couple of years ago. Very good guy.

You can get good quality renewable parts of all sorts from Navitron.org at a very good price. They were set up with providing high quality gear at reasonable prices as an ethos.

[adam2]

Home made solar air heater.
A very large shallow box of wood or metal. Insulate the back and sides with insulation board. Paint the inside black.
Cover with glass, preferably double glazing. Mount facing South and nearly vertical.
Fit insulated air ducts, one at the bottom and one at the top, these to go into the heated space.
Fit an electric fan to blow cold air from floor level into the bottom of the collector, and direct the heated air as desired in the heated space.
A very small PV system will power the fan.
A slightly larger system could power lighting etc as well.
In summer consider shading the thermal collector as it will otherwise get so hot as to be damaged.

[emordnilap]

He repaired my Solartwin pump for me a couple of years ago. Very good guy.

Same here, very reasonable rates and wouldn't accept payment for some things he did.

[BritDownUnder]

Googling some keywords gave a lot of solar air heaters based on a box with glass front and cans painted black to absorb the heat. What looks like a computer fan then forces the air down a tumble dryer style pipe to the desired place.

The tricky bit looks like gluing all the cans together.

Treehugger

[emordnilap]

Googling some keywords gave a lot of solar air heaters based on a box with glass front and cans painted black to absorb the heat. What looks like a computer fan then forces the air down a tumble dryer style pipe to the desired place.

The tricky bit looks like gluing all the cans together.

Treehugger

The cans sort-of stack on one another so, if the box is laid down, a bit of silicone down the outside back of them would probably do. They'd also need to 'stack' so as to finish a few centimetres from the top, to give room for the stacks' output.

[Catweazle]

After looking at some DIY videos I ordered some aluminium door screen material, it's not expensive, and I don't have access to a load of tin cans.

https://www.youtube.com/watch?v=OUeqTAUnaVo
https://www.youtube.com/watch?v=PyVPNOUpOVg