How did you come to my-PV?

Group VHC, a local company, that is active in different regions of Belgium and focuses on heating and solar energy, is noticing a steady increase in photovoltaic-assisted heating. There are more and more installations venturing into heating with photovoltaics – the increase is also noticeable compared to installations of oil and gas heating in Belgium.

The company first became aware of my-PV in 2017 at the ISH in Frankfurt, the world's leading trade fair for building, energy and heating technology. The first my-PV product used was ELWA, for the production of hot water. In the meantime, Group VHC works with a number of my-PV products, such as the AC•THOR, whose application is presented in this reference project.

Obstacles/specialities during the installation

AC•THOR is really easy to install and configure with the immersion heater. An existing pellet heating system from ÖkoFEN has the option of integrating a third-party system – in this case with AC•THOR. AC•THOR was the chosen product because it has a hot water backup function that maintains the desired minimum temperature overnight. This is important for operation at night, where sufficient hot water must be available as well for comfort purposes.

Brief explanation of the system – what should be mentioned?

The pellet boiler is switched off from mid-March to September, which means that it is not used for heating in spring, summer and early autumn. The surplus PV energy is optimally used with the electric heating by AC•THOR. The required temperature is set to 85° C to get the maximum out of the photovoltaic system. In order to draw as little power as possible from the grid, the hot water backup is set to 40 °C; this means that if the temperature drops below this, AC•THOR uses grid power to heat water. In winter, however, AC•THOR and the pellet boiler work together and only when the water temperature drops below 60 °C, the pellet boiler switches on during the winter months.

Persons in the household – Hot water requirement etc.?

There is a large hot water requirement for the 4 people in the family house with 260 m². The two adults live in the family house together with two teenagers. AC•THOR supplies the 360 ​​liter hot water storage tank with excess electricity via a 3 kW immersion heater from the photovoltaic system and thus heats it up with electricity from the roof. This way, the hot water preparation for the four residents is secured during the day in a cost-effective, environmentally friendly and sustainable manner.

In order to meet the comfort requirements regarding the temperature of the hot water in the morning, i.e. after the night, the hot water backup is switched on at AC•THOR.

This ensures a fixed temperature that can be reached, even if there was not enough sunlight the day before, to ensure the residents’ showering experience.

Any cost changes/ROI?

With a solution like AC•THOR, about 7.5 kWh of photovoltaic electricity is consumed daily by the system itself. In economic terms, this is a saving of between 3 and 4 euros per day, so over the course of a year, this results in a saving of about 1,000 euros, which can be generated by the increased self-consumption of photovoltaic electricity.