Building This DIY Solar Air Heater Can Save You $1000 per Winter

The solar air heating collector is a quick and simple way to get started on alternative energy. Although is a quite simple array, it can make you save a lot of money on energy bills. Just basic thermodynamics, not moving parts, cheap and effective.

Solar Air Heat Collector
Installed Solar Air Heat Collector

How does it work?

Thermosiphon Diagram – Hot/Cold Air Flow

Also read: How to Beat the Agony of a Dying Phone Battery

The two principles at work are:

Dark surfaces absorb light. Any black colour object absorbs all wavelengths of light and reflects none, that’s why it appears black. As you know, light is energy and as being absorbed into something it can turn into heat. The main part of the box will have black-coloured material in it to capture heat from the sun.

That heat gets transferred into the air in the box. As the air warms up, it wants to rise out of the box. As the warm air rises, it pulls cooler air into the box. This is knowns as the thermosiphon effect. This is a method of passive heat exchange, based on natural convection, which circulates a fluid (air in this case) without the necessity of a mechanical pump.

Step by Step DIY!

The most effective and efficient design uses black metal window screen as the heat collector. This works great because it has a large surface area and is designed for maximum airflow already. If you can get black metal window screen, that is the best. If you can’t, it’s easy to spray paint the screen black.

How much would you save?

If one heater can keep the living room warm for all the daylight hours, that’s 6 to 10 hours of not having a heater on. Our average living room would normally need a 3200-watt electric heater. If it’s running for 10 hours, that’s 32-kilowatt hours (kWh). Let’s say electricity costs you 19 cents/kWh. That’s over $6 per day or $42 per week. From October to March, that’s about $1022.

What would you do this winter with your extra $ 1.000?

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First, what crap. The solar isolation on a sq. ft. of vertical collector is about 200 BTUs a hour between 9 am and 3 pm. A well made air heater will capture and bring 100 of those BTUs into the house. allowing for cloud cover, often 6 days in a row where I live. A sq. ft. of collector will bring less than 100,000 BTUs into a house per year. I pay 70 cents delivered for 100, 000 ( a therm ) of nat. gas. I have , and have had for 20 years, commercially made selective surface, low iron… Read more »


Is it the most efficient design? The air will go up in seconds with a flat vertical surface, barely enough time to heat up sufficiently. In the other designs I have seen, the air usually goes through an aluminum pipe that zigs zags from the bottom hole to the top hole, so the air has a much longer way to go and to collect heat. Most DIY designs use recycled aluminum cans that are cut on both sides, assembled into the zig-zag pipe and painted in black. I tried building one, but collecting cans is a hassle when you never… Read more »