Glazed Flat Plate Solar Collectors
Glazed flat plates are constructed with insulation on their back and sides and are covered by a transparent cover. This reduces the heat loss to the surrounding area and therefore improves the performance of the collector compared to an unglazed version. These collectors can be integrated with the roof, mounted on the roof or façade mounted.
Evacuated Tube Solar Collectors
Evacuated tubes are highly efficient even with low solar radiation, as well as in circumstances where there is a large temperature difference between the absorber and ambient temperatures. In general, evacuated tubes are more expensive than glazed flat plate collectors and cannot be installed integral to the roof. Evacuated tube collectors use glass tubes in which a vacuum is created. This acts as a source of insulation, reducing heat losses from the collector and making the product very efficient. There are two types of evacuated tube collectors: direct flow and heat pipe collectors.More information (PDF)