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Types of Viessmann Solar Collectors
Evacuated Tubes and Flat Plate Thermal Solar Collectors
- Flat Plate Solar Collector. The Flat plate System is designed with an insulated, waterproof box containing a dark absorber plate under one or more translucent or transparent covers. Conducting fluid. Conducting fluid or water pass through pipes located below the absorber plate. The flat plate does not have the insulating benefits of the evacuated tube, but is still the most common type of collector in many nations. New advances in technology and manufacturing have brought the cost of making the evacuated tube system the standard of choice today in the United States.
- The Evacuated Tube Solar Collector. Evacuated tube solar water heaters are composed of parallel, glass tubes. There are several types of evacuated tubes, including Glass-Glass tubes, Glass-Metal tubes, and Glass-glass-water flow path tubes. Each type of tube technology is briefly described below.
- Type 1. Glass-Glass Tubes. Glass-Glass tubes consist of two glass tubes which are fused together at one end. The inner tube is coated with a selective surface that absorbs solar energy well but inhibits radiant heat loss. The air is withdrawn "evacuated" from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss. These tubes operate very well in overcast conditions as well as low temperatures. Because the tube is 100% glass, the problem with loss of a vacuum due to a broken seal is greatly reduced. Glass-glass tubes have a number of purposes, including heat pipe, direct flow, or U pipe configuration Focus Technology uses a high efficiency heat pipe and heat transfer design to conduct the heat from within the tube to the header.
- Type 2. Glass-Metal Tubes. Glass-Metal tubes consist of a single glass tube. Inside the tube is a flat or curved aluminum plate which is attached to a copper heat pipe or water pipe. The aluminum plate is coated with Tinox. These tubes are very efficient when they are not having problems relating to a loss of vacuum. Glass to metal sealed tubes can have problems relating to a loss of vacuum. The seal can foil from years of continuous years of expansion and contraction between the two different materials. Glass-glass tubes are much more reliable and cheaper in the long run than the more efficient but prone to break down glass-metal tubes.
- Type 3. Glass-Glass-Water Flow Path. Glass-glass water-flow-path tubes incorporate a water flow path into the tube itself. The only drawback with these tubes is that if the tube is ever cracked water will pour from the collector onto the roof and the collector must be shut down until the tube is replaces
- Concentrating Collectors. Concentrating Collectors for residential applications are usually parabolic troughs that use mirrored surfaces to concentrate the sun's energy on an absorber tube containing heat-transfer fluid, or the water itself. This technology is outperformed by the evacuated tube solar collectors.
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