How does evacuated tube technology work? |
Evacuated Tube Technology works on the same principle as a thermo flask. The tube is designed to capture as much sunlight as possible but then to maintain the stored heat and not conduct it away to the surrounding air. It consists of two layers of borosilicate glass with a vacuum layer between them. Sunlight is transmitted through the vacuum and its energy is transferred to the heat pipe inside. A small amount of evaporative fluid in each tube transfers this heat to the manifold above. This in turn heats the geyser water which is being circulated through the manifold. The efficiency means that more than 90% of the sun’s energy which hits the collector is transferred to the water.
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How long have evacuated tubes been around? |
Evacuated tube technology has been used in Europe, USA and China for over 15 years. Evacuated tubes are relatively new to South Africa for the simple reason that in the past our electricity has just been too cheap. This resulted in very limited incentive to bring advanced technology to the country.
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No. Split systems (geyser in roof) almost always have to be pumped systems due to the fact that the geyser is below the height of the panels. The pump and controller need a small amount of electrical power to operate. Some systems employ solar driven pumps to circulate the water through the collector. We have experimented considerably with this option but have found that solar driven pumps are weak, sensitive to impurities in the water and have trouble bleeding air out of the circulation system.
Solar pumps have to be driven by an additional photovoltaic panel which is a lot more sensitive to cloud shadows which stop the pump from being powered. This leads to an inefficient system as the tubes are still being heated by the sun on even moderately cloudy days – but due to the pump not working, the hot water is not circulated to the geyser.
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Evacuated tubes get too hot in South African conditions - is this true? |
Here, once again, the SunScan collector is superior. Our collectors have a stagnation temperature of less than 203 degrees which is equivalent to that of quality flat plate panels. Other evacuated tube collectors have stagnation temperatures in excess of 250 degrees (some up to 280 deg!). This creates problems for any components in the system which are not designed for these high temperatures
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How long does an installation take? |
A team comprising a plumber and an assistant can carry out most installations in a day