April 12, 2022

◼ A solar-electric apartment building project in Graz

In the south of the Styrian capital, 8 apartments are heated and supplied with hot water with surplus from the photovoltaic system.

Completed in 2021, the new residential project in the south of Austria offers residential units with 8 condominiums between 50 and 70 m². A total photovoltaic capacity of 64 kWp is available on the apartment building, whereby each apartment can thus use approx. 7 kWp - partly placed on the roof (east/west oriented) or on the carports (south oriented). Thus, each residential unit is billed separately, each condominium has its own AC•THOR 9s.

So far the basic conditions. The special thing about it now, however, is that the power of the sun is also used for heating as well as for preparing the hot water in each individual apartment. For the customer, this means no loss of the comfort to which they are accustomed - quite the opposite.

The photovoltaic system provides so much energy that with the surplus, which is not used by the household consumers themselves, the owner of the condominium does not noticeably use the photovoltaic power during the day for heating the hot water as well as for the electric heating. At the same time, a common electric suspended storage tank from Austria Email with a capacity of 150 liters is installed in each apartment - a standard version supplied with surplus energy by our power controllers (AC•THOR 9s).

Only 100 kWh per month for electricity, hot water and space heating

This environmentally friendly and resource-saving design is also convincing in terms of costs and solar coverage. In the first months of operation in the spring of 2021, i.e. between March and June, only 100 kWh of public electricity were drawn per month. And that was for electricity, hot water and heating - an enormous value!

By far the greater part of the energy for these sectors came cleanly and free of charge from the in-house photovoltaic system (and that despite the heating season, at least in March).

Such low draws from the public power grid - as in this case - cannot be generated by photovoltaic heat alone. Here, at the request of the building developer, Enoiko GmbH, a 5 kWh battery storage system was also installed in the basement for each residential unit.

These additional installation costs for the battery storage raised the initial investment costs somewhat above the level of conventional building technology. However, additional savings are possible by eliminating the need for a battery storage unit.

The feedback from building developers?

"The my-PV technology is easy to implement and already planned for the next projects.

Once the concept has been understood by people after initial discussions, the question always comes: 'Why isn't everyone doing this?'", builders Martin and Manuela Reiner are convinced.

We also accompanied the project with a video - you can find it here (in German):