Posted by: Yes Solar Cape (Cape Town, South Africa) – 29 October 2010
When purchasing a solar water heating system consider the following 12 points, and evaluate each one before committing to a system.
1. Certification – what kind of certification does the system have? First prize is SABS Mark Approval. This is a higher form of certification than just an SABS Test Report. Mark Approval means that the entire supply chain of the product has been inspected and that SABS are confident that the product will consistently meet their standards.
2. Also look out for Solar Keymark certification (EU), and the German TUV standard.
3. Direct versus Indirect systems – basically, if you live near the coast you can install a direct system (no intermediate heat transfer fluid), but if you live somewhere that is prone to frost (i.e. temperatures drop below 4 deg), then you have to go for an indirect system. Where possible, go for a direct system, the heat loss between panel and geyser is lower.
4. Evacuated Tube versus Flat Plate collector – the respective suppliers / manufacturers of these systems place too much emphasis on this question. Rather look at the build quality, efficiency and durability of the collector, regardless of the type of technology it employs. Pay special attention to corrosion resistance – low quality stainless steel and shoddily galvanized metals will start to rust after a couple of years.
5. A quick way to measure efficiency is to look at the rebate a system enjoys. The rebate is simply a multiple of the Q factor of the system (which is a measure of its efficiency). But be careful to compare systems of the same size, e.g. a 200 litre system with a 200 litre system. Continue reading