Heat pumps play an important role with regard to the integration of renewable energies. In times when there is a surplus of renewable energy, electricity can be converted into heat at low cost and be supplied more independently of current demand. Here the project of a consortium linked to the Fraunhofer ISE is seeking to intelligently control heat pumps in order to adapt the consumption load to the times of the most efficient energy generation.

Due to the high number of existing buildings and low number of new constructions in Germany, measures aimed at achieving the CO₂ reduction targets must therefore always take existing buildings into account, too, and give them precedence. Hence, in this project, only heating systems in existing residential buildings are being evaluated and compared. For this purpose, the consumption of more than 100 heat pumps in private households is being recorded and compared over three heating periods.

After the first period of comparison, 20 heat pumps will be converted into regulated energy-efficient operation. In this way, each supplier can adjust the system according to the availability of the renewable energy sources and optimally dovetail supply and demand. The tested heat pumps fulfil all the requirements for intelligent control and have therefore been awarded the nationally applicable “SG Ready” certificate by the Bundesverband Wärmepumpe e.V. (Federal Heat Pump Association). SG stands for Smart Grids, i.e. intelligent energy supply systems. Heat pumps certified as “SG Ready” are equipped with several modes of operation that can be controlled remotely. Depending on the electricity price, this may be in full operation or in energy-saving mode.

On the consumer’s side, the energy consumption of the compressor, control system, heating element and heating pump drive (brine pump, ventilator, well pump) are recorded by the minute. The power consumption of circulator pumps in the heating system is also recorded. With hybrid systems, the oil and gas consumption as well as the heat flow are also recorded. every day, the data collected is conveyed to the Fraunhofer ISE, checked and evaluated, thus identifying and enhancing optimal solutions for the operation of heat pump systems in existing buildings.

The participants of the project funded by the Federal Ministry for Economic Affairs and Energy (BMWi) are the Fraunhofer Institute for Solar Energy Systems, the Bundesverband Wärmepumpe e.V., energy supply companies from the south of Germany as well as a range of heat pump manufacturers. The project with the registration number 03ET1272A is being funded by the BMWi between 2014 and 2018.