Evacuated Solar Hot Water
Solar hot water systems are continually evolving and the introduction of evacuated solar hot water collectors represents a move towards more efficient and durable solar hot water systems. The technology used in this evacuated tube collectors is preferred to that incorporated into flat plate solar hot water. Although the new technology does come with a bit of a higher cost the benefits that come along with it make the investment worth making.
The evacuated tube design used in this hot water system was developed in the 80s and boasts of strong glass. The design has several benefits including capturing sunlight better because of the larger surface that is constantly exposed to sunlight, more efficient heat transfer as a result of combining vacuum insulation and efficient absorber coating, durability because of the strong glass that makes the tube, easy and cheap replacement, suitable for subzero temperatures, more corrosion resistant than flat plate collectors, excellent performance in places with overcast conditions and better suited for small roof areas as the evacuated hot water system needs less roof space. The evacuated tube has a 15-20 year lifespan; therefore the system is fitted with a barium layer to prevent out-gassing and to indicate the vacuum status. This helps prolong the life of the system.
Evacuated tubes come in different structural designs including single and twin wall designs. The design of the tube will determine how the heat produced will be extracted. Direct water flow, heat pipes, pipe-in-pipe and U tube pipes are the most commonly used. This hot water system is also compatible with various storage capacities ranging from 175-320 liters. The biggest benefit of evacuated solar hot water heating systems is that they are very cost-effective and though the initial cost may be higher than for flat plate collectors, rebates on solar hot water and the benefits make a good return on your investment.