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AT CAD Team/AT CAD Team's DIY solar thermal collectors
Solar thermal collector T1
The solar thermal collector T1 was initially designed for the AT shower model, yet can also be used for a variety of setups. The batch heater is a heater like the one shown to the right but automatic temperature control (set to eg 40°C) should be added. As such a open-source design for this temperature controller should be made. The automatic control can be created in practice by 2 tanks --> 1 with cold(er) water (eg 20° or so; ambient temperature) and 1 with warm water (this tank can be the batch heater itself). The tank with colder water needs to be shielded from the sun (eg by underground placement, ...). The 2 tanks can be connected to 1 large(r) tank that will be the primary buffer for the shower (here the water needs to be 40°). The valves of the (hot&cold) tanks will be automatically controlled by the temperature controller. The batch heater itself may be fitted with a electric coil for heating when the water cannot be heated enough by the sun; in not so sunny areas the batch heater can be improved by targeting light at it with parabolic dishes.
Solar thermal collector T2
A evacuated tube collector is more suitable for circulating (pressurized) water heating systems. KWB's evacuated tube collector may be used, see 
- KWB's main site
- KWB's technical movie on how to construct thermodynamic solar panels
The Sietch's thermodynamic solar panel construction (which may be cheaper) http://www.thesietch.org/projects/solarthermalpanel2/index.htm
- https://docs.google.com/Doc?id=dcwtr665_166h58cmk Original document]