Bilder_AC•THOR 9s_HUAWEI_Ludwig Wahl_Drohne (1) my-PV

Photovoltaic heat for apartment buildings and holiday apartments

In a 500 m² multi-party house, hot water and heating are generated from photovoltaic energy. In the summer, two AC•THOR 9s take care of the hot water preparation for the whole house.


The Wahl family owns a 500 m² apartment building in beautiful Middle Franconia, more precisely in the district of Erlangen-Höchstadt. In the house, which was last renovated in 1996, there are three apartments and an additional holiday apartment in the outbuilding. Up to ten people live in the approx. 500 m² at peak times or up to six people can vacation in the holiday apartment. There was enough space on the attached hall to mount the 24 kWp photovoltaic system on the roof, which is aligned to the northeast with a 5 degree inclination.

The owner from Bavaria came across the my-PV solutions through a heating construction company and his own research on the Internet to optimize self-consumption and heating with environmentally friendly energy.

How the facility is set up

Three heating rods from ETA's primary heating system are installed in each of the two buffer tanks, each with a capacity of 800 litres. These are linearly controlled via the two AC•THOR 9s to load the photovoltaic yield into the buffer storage during the day. This heats the hot water for sanitary and household applications and prepares it for space heating and heating purposes.

The control and thus the surplus information can be queried directly from the built-in inverter or the built-in surplus detection in the sense of the system openness of my-PV. This means that there is no need to install a separate meter, which in turn saves costs for the customer. A total of three inverters from HUAWEI are installed as well as a blackout box for possible emergencies.

The excess electricity detected from the photovoltaic system is first forwarded to the home consumers, then to a 15 kWh electricity storage unit (also from HAUWEI) and then to the heating rods in the buffer storage tanks. Linear control is the decisive factor here, which is done by the two AC•THOR 9s, which control the surplus to the exact watt and thus distribute and control the fluctuating PV yields in a targeted way.

The customer from Middle Franconia is very satisfied with the environmentally friendly and cost-efficient solution from my-PV, but also has possible ideas for further developments in mind, as he states: "I think it's a very good addition for the summer. Our plan is to switch off the ETA heating (boiler) and to manage the hot water preparation with my-PV. Unfortunately, we are having two systems. It would be great if the whole thing were software-controlled, i.e. it would be recognized what the solar radiation will be like, the ETA boiler would switch off and automatically access the my-PV photovoltaic surplus control.”

More information about the project can be found here.

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