DIY Solar Collector

A do-it-yourself solar collector can turn solar energy into thermal energy.

Thermal energy comes from heat, and should not be confused with electrical energy that comes from a solar panel.  A solar panel converts the sun’s energy into electricity, whereas a solar collector simply absorbs the sun’s radiation and uses it to create heat.

A simple do-it-yourself solar collector can be made out of a typical pressed-steel central heating radiator. This is inexpensive, and can even be purchased second-hand.

If you use a second-hand radiator panel, be sure that you remove the paint from the front surface and reapply primer. Size will not matter, but you should consider keeping it around one square meter or less. Keep in mind that you’ll be installing the solar collector on your roof, and anything bigger will result in the difficulty in handling it.

Once you’ve selected your radiator panel, the next step is building a case for it. It is recommended that you assemble the case in its final position, to make your job easier. Then there will be no need to hoist the entire solar collector up onto the roof after it has been built.

The case is just a simple box with a front cover glazing, made out of the 3mm glass which is typically used for windows. The glass must be purchased after you’ve assembled the box. Measure the case, and buy the glass already cut to size. Be sure to leave at least a 2mm gap around the glass, to allow for its expansion. The glass cover must overhang the lower edge of the case, by at least 12mm. This will keep rain water from seeping onto the panel.

Making your DIY solar collector water-proof and keeping it dry is not an easy task. You might prevent rain water from entering, but over time, internal condensation can occur. You can prevent this by inserting 5mm breathe holes along the lower side of your box.

Insulation must be placed behind the collector, because internal temperatures can reach up to 140 degrees Celsius. Avoid using the cheap types of insulation, such as polystyrene, because these tend to shrink or melt. To limit air movement, ensure there are no gaps between the panel and the insulation.

This homemade solar collector should be cheaper than those available in the market. The thermal efficiency of a central heating radiator is fairly comparable with the commercial solar collectors. If you’re looking for a cheap way to heat your water supply, this is one of your options.