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Social housing - Skødstrupbakken

Hybrid system with solar panels and a battery is now providing a Danish housing association with green and inexpensive power

23/11-2020

The housing association Skødstrupbakken, near Aarhus, is a home of the future. In the construction of the building, sustainable power and electricity consumption is incorporated in an innovative new way by means of a hybrid systems and solarpanels with an accompanying battery.

The construction is the first of its kind in Denmark and should inspire housing associations across the country (and abroad) – within new constructions, renovations, and energy optimisation.

Green social housing surrounded by nature

You do not have to go far from the city to experience a home of the future. 15 km outside of Aarhus, the housing association Skødstrupbakken is in scenic surroundings with its own preserved lake.

The department, which is located close to both forest and water, is one of the housing association AlmenBo Aarhus’ newest additions. With the solar and battery installation in Skødstrup, the aim for AlmenBo Aarhus is to come closer to a greener everyday life.

“AlmenBoAarhus is currently undertaking a massive green transition which is a part of Aarhus municipality’s objective to become carbon neutral by 2030 – this is achieved by, among other things, installation of solar panels, hybrid systems, re-insulation, optimisation of heating plants as well as replacement of windows or the like,” states Jesper Holze, project manager in the association.

The residents at Skødstrupbakken are primarily families who want to contribute to the green transition. The department, built in 2018, is not just green in the classical sense, being located in the nature.

Skødstrupbakken is also green in the sustainable sense, which is reflected in the association’s decision to install both solar panels and a battery solution. A decision which should lead to inspire other housing association across Denmark.

The hybrid system was decided right from the beginning

The idea of providing department 52 and its 33 residents with a so-called hybrid system originally came from AlmenBo Aarhus. An idea that has been in the pipeline right from the beginning.

“From the beginning of the project we have been in contact with VisBlue regarding the establishment of a hybrid system – but we are also aware of the difficulties of finding the financial resources for such a solution, considering the resources that are commonly available in social housing projects. Therefore, during the construction phase, we considered all routes, from the roof to the technical room, as well as reserved space in the room for a battery solution. Last-mentioned can be really expensive, if it is done after the initial construction work,” Jesper Holze explains.

Even though the idea came from above, it was in the end Skødstrupbakken that made the final decision. And here, a majority voted in favour of the idea.

The decision pleases Jesper Holze, “We are extremely delighted that the residents of Skødstrupbakken had the same attitude as us with the establishment of a hybrid system. It fits in well with the green profile of AlmenBo Aarhus.”  

The idea of not only installing solar panels but also a battery solution makes sense. It makes sense for the environment, but especially also financially. With both solar cells and a battery, there is money to be saved on the residents' electrical bill.

New constructions must be born with solar panels and batteries

If you ask the chairman of the board at Skødstrupbakken, Pia Mouritzen, the new hybrid investment is the only right direction to go.

“New constructions must be born with solar panels and a battery. It is without a doubt the road ahead. The green agenda is something we are passionate about, but it is also an essential factor that the hybrid system enables us to have cheaper housing,” she states.

With the help of the right financing, Skødstrupbakken is able to invest in both solutions without increasing the rent. Pia Mouritzen explains, “it is crucial that there is no rent increase. If there is, then the support of the majority disappears –because even if the investment is green, it should not end up producing red numbers.”

"New constructions must be born with solar panels and a battery. It is without a doubt the road ahead. The green agenda is something we are passionate about, but it is also an essential factor that the hybrid system enables us to have cheaper housing."

- Pia Mouritsen, Skødstrupbakken

Danish suppliers

Both the solar panels and the battery come from local Aarhus companies which is a common thread in the grey brick construction in Skødstrup. The solar panels are produced by Mikael from Risskov Teknik & Solar and the battery by Søren from VisBlue.

The local suppliers make sense for Jesper Holze, “it means a lot to us that we succeeded in creating a collaboration with two local companies, enabling Aarhus to further develop sustainable solutions of the future together. So, a big thank you to VisBlue and Risskov Teknik & Solar for the valuable collaboration.”

The solar panels cover over 452m2 of the department’s roofs and generate on average 75,000 kWh per year, leading to an annual saving of roughly 11.4 kilos of CO2.

To translate these numbers into something comprehensible, it means, that the solarpanels produce enough power to cover the annual electricity consumption of 30 families.  Further, the CO2-savings of the solar panels is equal to planting 556 trees every year.

Mikael Kjærgaard from Risskov Teknik & Solar is also pleased by the green hybrid project, “AlmenBo Aarhus and the residents at Skødstrupbakken have been eager to initiate the project and vi are pleased to be delivering a part of AlmenBo Aarhus’ first solar panel system with accompanying battery. We greatly appreciate the collaboration with both AlmenBo Aarhus and VisBlue, as both parties show great commitment in the sustainable development goals and sustainability – a passion we share with them.”

He continues, “throughout the project, there has been great interest from both the housing association and the department, and the solar panels and battery are in their own league, as well as one of the first hybrid installations of its kind.”

"It means a lot to us that we succeeded in creating a collaboration with two local companies, enabling Aarhus to further develop sustainable solutions of the future together. So, a big thank you to VisBlue and Risskov Teknik & Solar for the valuable collaboration."

- Jesper Holze, AlmenBo Aarhus

The battery increases the utilisation of the solar panels

But without a battery, a large part of the green power from the solar panels will not be utilised by the department. By installing a battery solution, Skødstrupbakken is now able to collect and store the power that the solar panels generate during the day, and utilise it at any time of the day, even when the sun is not shining.

CEO at VisBlue Søren Bødker explains, “when the sun is shining in the middle of the day and produces a lot of green electricity most people are at work or in school and are therefore not utilising the electricity optimally. Therefore, it makes sense to install a battery which can collect and store the sustainable energy until you need it, e.g., during the evening and at night when you are making dinner or watching tv.”

The battery solution at Skødstrupbakken is a so-called redox flow battery – a different battery type where the power is stored in two tanks filled with liquid. The flow battery has multiple advantages over common battery types, among other things being scalable and providing a longer lifetime, and also being 99% recyclable and non-flammable.

The battery at Skødstrupbakken is 8kW and 40kWh, which means that they are now able to utilise approximately 10% more of the power produced by their solar panels.

The hybrid system helps the residents at Skødstrupbakken to contribute to the green transition at the same time as getting a cheaper electrical bill.

The green dreams have just begun

For the department in Skødstrup their journey is far from over. They have more projects under way.

“We would like to make a bigger garden with a utility bed, fruit bushes and insect-friendly plants to help the local biodiversity on the way,” Pia Mouritzen states.

Furthermore, the department has initiatives such as a common toolshed and cleaning days on the drawing board. Electric vehicle charging stations, so the department is able to make even greater use of the solar panels and the battery is also under way.