KOSTAL Pressebereich
Freiburg, 26/10/2023

13 years of pv in a crèche: A success story

When the mix is right, things sometimes happen very quickly. This was the case in 2010 in Rothenkirchen, a district of Steinberg in the Vogtland (Saxony). The mayor of the community of just under 3,000 inhabitants was a master electrician with a lot of photovoltaic experience. He initiated the construction of a photovoltaic system on the day-care centre. In 2010, it was connected to the grid and has since provided the community with income from feed-in tariffs, which are reinvested in the crèche and kindergarten - energy for the future of the community.

Solar power enables investments in equipment and maintenance

13 years ago, on the initiative of the then mayor, a 25-kilowatt peak photovoltaic system was installed on the roof of the Rothenkirchen day-care centre. At that time, it was designed as a classic feed-in system that feeds its entire production into the public grid. With a feed-in tariff of around 40 cents, the system generates attractive income, which the municipality invests in the equipment and maintenance of the day-care centre. This year, for example, with the help of the PV profits and subsidies, additional playground equipment worth 12,000 euros was purchased for the outdoor area.

The subsidy for the day care centre's PV will expire in seven years. After that, the system is to be converted to self-consumption. In the future, an electricity storage system could be purchased to hold back the excess capacity of the day for the sunless morning hours of the following day. The 25 kilowatt peak of the system is easily enough to cover the annual electricity demand of the crèche and kindergarten.

Inverters from KOSTAL as saviours

The photovoltaic direct current is now converted into alternating current by three KOSTAL inverters, one for each orientation of the three roof surfaces, namely south, south-east and east. With this, the nursery PV is once again delivering full power - on average 22,000 to 23,000 kilowatt hours per year.

"The income from photovoltaics is a lot of money for a small community like ours. We are all the more pleased that we are now benefiting from the foresight of our former mayor and the municipal council," Beatrice Küttner comments on the Kita-PV initiative.

But the current mayor is also counting on renewable energies for the future. A photovoltaic system for self-consumption is to be installed on the school building as well. And if the electricity from the existing day-care centre PV should not be sufficient for the property after all, or if electricity consumption in neighbouring buildings is made easier by the legislator, the roof of the day-care centre offers space for additional PV modules.
Facts and figures

    • 25.2-kWp photovoltaic system, divided into three system sections with three orientations: South, south-east, east
    • Three KOSTAL PLENTICORE plus inverters (one for each orientation). In 2010 this was standard. Today, fewer devices with multiple MPP trackers could be used.

Ideal for self-consumption: PV orientation from east to south

The nursery extension surrounds the older building, which houses the kindergarten, on three sides (south, south-east, east). This means that the system, which consists of three parts distributed parallel to the roof, has an ideal orientation for self-consumption: the eastern part already supplies solar energy in the early morning. Then the south-east part takes over and finally the south side, which supplies power until late afternoon when the facility closes. "However, self-consumption is not an issue until the subsidies expire," says Dipl.-Ing. Beatrice Küttner.

The civil engineer is the property manager in charge in Steinberg and responsible for looking after the photovoltaic system. "The former mayor who initiated the plant in 2010 was a master electrician and chairman of the electrical guild. He already had a lot of experience with photovoltaic systems back then and has really done the community good with the system," says Küttner. The technically trained eye can see at first glance that not only the available space has been optimally used, but also that all distances to the roof edge are correct.

The modules were installed parallel to the roof on the 10-degree pitched roof. This may reduce the performance of the system somewhat, but it is a safe and therefore sustainable installation, so that the system can be operated for many decades.

Washing machine, lighting, digital devices: full power supply from the roof

"In the nursery school and crèche, ten adults work in shifts and look after around 60 children every working day. Consumers include the washing machine, lighting and digital devices. The building is already equipped with larger radiators that can operate at a flow temperature of 35 degrees and are thus prepared for operation with renewable energies, e.g. an electric heat pump or similar," Beatrice Küttner explains. The facility is open from 06:00 to 16:30. These are ideal times for maximum self-consumption, especially given the optimal orientation of the facility.