I have been thinking about making a solar heater for preheating my hot water for a while. After reading tons of great information from other diy'ers I started gathering stuff for my build. My goal was to get this build for as low cost as possible while also having a system with decent performance.
For starters I got 2x 4m^2 double glazed windows and rockwool insulation. Both was given away from someone that was refurbishing their house.
The collector is made with plywood bottom, plank sides, 5cm rockwool for insulation, 100m of coiled pex tubing painted black and a double glazed window pane.
The tank which currently holds 720L was made with a pallet with walls from stacked pallet frames with epdm tarp and 30cm rockwool insulation. Inside the tank I have coiled up some more pex (about 70m of 15mm) that preheats the water for my electric heater. I'm planning to add an extra 20m of copper for added efficiency.
The collector is placed on a south facing side of my house with 25m of pex run through the attic and down to the crawlspace to the large tank beside my electric hot water tank.
For controlling the pump I'm using a Arduino controller with ethernet. That way I have more possibilities when it comes to logging and displaying the performance of my system. The controller have 4 sensors at the moment: 2 at the input/output from the collector, one in the tank, and another in the collector.
The performance of my collector seems ok but I'll have to wait until spring before getting some real heat out of my system as the winter months in Norway doesn't get much sun.
Anyway the "crude, under development" website running on my arduino is located at
fogdeveien.ddns.net