The new standard in water heating

Here's what we can say right away: With photovoltaic heat, the building – just like our own company building – is self-sufficient in terms of energy!The residential building project in southern Austria was implemented in 2020 by a small family business with a total of 45 employees. A total of 4 apartments are available to tenants in the residential building, with each apartment of a size of 70 m². The Styrian property development company VIVA-Haus carries out projects, starting from a green field until the handover of the keys. It's not just about cost efficiency, it's also about reliability. In order to also improve in the field of sustainability, new technologies are used in their projects.

Exactly this was realized in 2020: In scope of this residential construction project, a 16.8 kWp photovoltaic system was installed on the roof of the building, which is oriented towards east/west and integrated on the west-facing facade and on the balcony railing. Each apartment has a 150 liter hanging storage tank with a 3 kW heating element. This cartridge heater in the hanging storage tank is supplied with the available excess power from the photovoltaic system by an AC•THOR installed in the apartment. As a result, the required hot water is prepared decentrally in the apartments during the day, using the power of the sun.

The required energy is for the most part of the year drawn from the grid-connected photovoltaic system. The surplus information for the my-PV control is queried from the SolarEdge inverter. Some of the PV modules have also been integrated into the building facade, which means that significant solar yields can be achieved during the cold season as well.

Hot water even during bad weather

While the boiler is heated to 60 °C when the weather is nice, the storage tank temperature is kept at least at 45 °C when the weather is bad. This way, the purchase of electricity from the public grid is limited to a maximum and there is always residual storage capacity available for excess. But even during this time, the tenant does not feel any loss of comfort. However, should a tenant wish to increase the minimum temperature, the housing developer can make such adjustments at any time, even from the office.

Feedback from the housing developer

For Arno Hernach, decentralized photovoltaic water heating will be the future standard for his housing projects! While he has already relied on classic pipe-bound solar thermal energy in the past, he now sees the future in photovoltaics. PV is more economical for property developers and it also is maintenance-free.

In the apartments, space heating by means of infrared heating is also characterized by a solar-electric energy supply with low investment and operating costs. Arno Hernach, the owner of the property development company, would like the legislator to take up the topic of photovoltaic heat more intensively. In his opinion, this is the future in apartment buildings.

More information on this project can be found in the reference description.