Solvarmeanlæg fra Batec Solvarme A/S, Velux Danmark A/S og Sonnenkraft Scandinavia A/S – målinger og beregninger

The aim of the project is to test marketed solar heating systems in a laboratory test facility and to establish contact between installers of solar heating systems and house owners wanting to install solar heating systems.
Two small SDHW systems from Batec Solvarme A/S and from Velux Danmark A/S have been tested under realistic conditions side-by-side with a small solar combi system from Sonnenkraft Scandinavia A/S. The thermal performances of the systems have been measured for a long test period. Measured thermal performances have been compared to thermal performances calculated with detailed simulation models for a short period for the three systems. A good
agreement between measured and calculated thermal performances was achieved for all the systems.
The yearly thermal performance for the three systems was calculated for different hot water consumptions based on the weather data from the Danish Test ReferenceYear. The thermal performances are compared to the thermal performances of earlier tested marketed solar heating systems.
The thermal performances for the three tested systems are lower than the thermal performances of the most efficient of the earlier tested systems. The reason is that the three systems are high flow systems with a hot water tank with a built in heat exchanger spiral, which equalize temperature differences in the hot water tank during operation periods of the solar collector. Low flow systems with a highly thermal stratified hot water tank, such as a mantle tank, have higher thermal performances than high flow solar heating systems based on spiral tanks. Further, two of the tested systems are based on hot water tanks with pipe connections to the upper part of the tank. These pipe connections results in high thermal bridges and thereby in a low thermal performance of the solar heating system. It is recommended to use hot water tanks with no pipe connections and penetrations through the insulation in the upper part of the tank. The tests form a good basis for development of improved marketed systems.