I received this email from a university colleague:
In reading one of your articles recently I noted that you have recently installed a solar water heater on your home. If so, I would be very grateful to know which product you have installed, as I'm contemplating a similar installation.
This was my response:
I went with a 3 m2 flat plate black copper tube collector close-circuited to a 200 litre geyser, all externally mounted and thermo-syphoning. It is complemented by a programmable logic controller for the electric back-up heating supplied by Eskom as a condition for receiving the subsidy.
I was impressed by my supplier's ability to recommend an installation to fit the customer's circumstance, their flexible roof mounting system, and the fact that their products are SABS accredited. In retrospect, I would have gone with an evacuated tube system - from all I gather, they are more effective in gathering the solar energy.
A life cycle assessment done by some of our postgraduate students to determine "energy payback time" (i.e. the time it takes to recover the energy embodied in the materials) showed that this less than 6 months. From a climate change mitigation perspective, adding another square meter of collector area is definitely recommended!