Major project with 12 AC•THOR

District heating from PV

In an apartment building in Vienna, 12 AC•THOR control 12 my-PV Immersion heaters.

Datos sobre el proyecto

PV power
Type of building
Heat storage size
my-PV product in use
Operation mode
System control by:
PV am Dach my-PV

In a residential complex in Vienna, the energy from a 47 kWp photovoltaic system is used to support the district heating network. Due to the limitation of the feed-in power by the grid operator, the solar power generated is converted into heat in an 800 litre buffer storage tank before the PV power is shut off.

Heat pumps were out of the question due to the high temperature in the heating network. In addition, their drive power cannot be regulated, which is a basic prerequisite for combination with photovoltaics. Only heating elements in combination with the power controllers from my-PV meet these requirements. With the AC•THOR, their output can be regulated linearly. A property that is essential for PV heat applications.

This not only generates clean thermal energy, but also mitigates one of the biggest problems of decentralized power generation: the public power grid is under increasing pressure to regulate the many small energy suppliers and maintain the voltage. By reducing solar electrical surpluses, the power grids are relieved and the electricity generated is used efficiently on the spot.


Photovoltaics are now so inexpensive that even the solar district heating support has become solar electric.

How it works

The superordinate energy management records the energy at the inverter and reports it to the AC•THORs. These then ensure the precisely regulated output of the heating elements. The implemented control system also helps to precisely maintain the desired flow temperature in the district heating network.

There has not been anything comparable yet

The use of PV electricity for water heating in residential buildings is a young issue in itself, but supporting a district heating network is something completely new. This project opens another application for heat with photovoltaics. In recent years, technology has almost replaced classic solar thermal energy in residential buildings, but this has not yet been the case for large-scale systems (industrial process heat, district heating). However, due to the continuing decline in module prices, such projects can now also be realised with PV.


Due to the fluctuating generation of solar power, exact power control of electrical heat generators is a basic requirement for combination with photovoltaics.

Advantages compared to solar thermal systems

The technical advantages are manifold. "Cables instead of pipes" facilitate installation and operation considerably and even high target temperatures can easily be achieved without drastically increasing losses. Compared to solar thermal systems, 90% less copper is required. Pipes, pumps, valves, expansion vessels, antifreeze etc. are no longer required, which greatly simplifies solar thermal technology.


With the further expansion of photovoltaics in the cities, the use of PV surpluses will from now on also include the possibility of feeding into district heating networks.

PV am Dach my-PV
Wärmespeicher mit Einschraubheizkörper my-PV
PV am Dach my-PV
Übergabe an das Fernwärmenetz my-PV
Leistungsmodulation der Heizstaebe my-PV
AC-THOR Seitenansicht


in use

Simple & efficient: AC•THOR controls electrical heat sources depending on the availability of PV energy and heat demand. And that for both hot water, as well as for space heating.

More infos about AC•THOR

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