Heat pump support with the ELWA

An uninsulated old building with hybrid heating in Thuringia benefits from solar energy in the buffer storage. The heat pump is thus supported by the ELWA.

An uninsulated old building with 130 m² was the starting point for the solar project of Mrs. Linke from a small community in the rural area of ​​southern Thuringia in Germany. The single-family house built in 1929 did not offer many options for the heating system, so it became a hybrid heating system. In addition to oil heating, a heat pump was used. With the necessary heating requirements for the two floors of the existing old building, electric – or better still, solar electric – room heating would not have been possible either. Still, the power of the sun can be used in the house. The 500 liter buffer tank offers enough storage volume to store the solar energy in the tank or to support the primary heating.

For the homeowner’s partner, Mr. Oßwald, the solution was clear after doing research on the internet and finding information on the my-PV website. It should be inexpensive, efficient, and easy to retrofit, so the choice was clearly the ELWA.

The direct current solution from my-PV, which can be connected directly to the photovoltaic modules, uses the 2.24 kWp PV system to directly pass on the photovoltaic power generated in the modules to the heating element – and this is linearly controlled!

The roof is the challenge

The challenge of this project was the unfavourable roof orientation of the house and the outbuildings, which would not have allowed any other type of installation than the one chosen: Due to the inclined elevation on the house wall and the therefore almost vertical orientation of the PV modules, there is a noteworthy yield in winter as well, which from the ELWA is converted directly into heat in the buffer tank. In this way, the heat pump and oil heater are relieved and "forced" to fewer and shorter switching cycles, which means that the operating time of both primary heaters can be reduced and the service life extended.

The implementation in detail

The cost-effective, efficient arrangement of the photovoltaic panels, which were to be placed alongside the heat pump with minimal installation effort and the shortest cable routes, was decisive for the implementation of the project. At the same time, the maximum output can be achieved with minimal effort for retrofitting, in order to minimize operating costs for the uninsulated single-family house and to relieve the primary heating system.

The ELWA is located in the 500 liter buffer tank of the heat pump, i.e. in the heating circuit. This is permanently hydraulically connected to the combi storage tank of the oil heater. The hot water required is therefore heated in the combination storage tank of the oil heating system, even though it is not running in summer. During summer, only the heat pump runs, but now effectively supported by the ELWA. If there is a need for heating in the transitional period and in winter, the oil heating "steps in" automatically.

And what does the customer think about the solution with the ELWA?

"The planned support of the existing heat pump by the ELWA works very well – especially on sunny days we are satisfied with it. The only problem is that the sun doesn't always shine - but that's not because of the ELWA!

Since then, the use of the ELWA has significantly reduced the number and duration of the heat pump's switch-on cycles!" summarizes Mr. Oßwald, the patron of the reference project in southern Thuringia.

More information about the project can be read here.