Build your own Active solar hot water heater - ebook

This very well illustrated plan(photos) will guide you though making a solar water heater using parts form an old fridge. Easy for beginners - just hand tools required.

Extract from the plan
A word of warning, this panel works VERY WELL. We tested it on a very sunny day and within seconds the water coming out of the panel was hot enough TO SCALD. I burned my fingers. This very hot water is only formed when the water inside the panel is allowed to sit for about a minute without moving. If the water is moving (do to the gravity siphon) the water exiting the return pipe is about 110 degrees, and while hot, will not burn you.

The water does not flow through the panel very fast (as the pipes are very small) but that is sort of a good thing as it allows the water to heat up a lot on its journey through the collector. It does take a while to heat up a 5 gallon bucket of water, I ended up building an insulated return bucket that was all black and sealed on the top except for the port where the water tube enters. This kept the returned hot water hot long enough to be of use. I let this guy run for a couple of hours one hot sunny day and heated up a five gallon bucket of cold water (measured at 70 degrees F) to over 110 degrees F. The temp that day was about 76 degrees F. If the water is allowed to sit in the panel for several minutes and then forced out (by blowing in one of the hoses) the water was measure at 170 degrees F. All in all we are much happier with the performance (and cost) of this panel. It performs much better than the previous one.