Housing cooperatives install Stockholm’s largest solar electric system
On 26 May 2014, the solar electric system was inaugurated at the Brf Kabeludden and Brf Långbänken housing cooperatives in Täby. ÅF assisted the cooperatives throughout the process with a feasibility study, planning and design, and procurement of subcontractors.
The housing cooperatives investigated various alternatives, such as geothermal heating, preheating of incoming air to heat pumps with the help of geothermal heating, and solar panels with district heating lines drawn to the buildings. Given the condition of the housing, any solution that required a new and water-borne system would be prohibitively expensive.
The organisations were left with a choice between solar panels and preheating of incoming air. Solar panels gave a higher return on investment and a shorter payback time. The government subsidy of 35% for investments in solar power had a large impact on the estimates. But their location with roofs facing directly southward and a good angle for solar arrays was also of major importance. By covering nearly all of the south-facing area of the buildings, they have been able to produce substantial amounts of self-generated electricity.
”On average, our housing cooperatives consume around 800,000 kWh per year. We expect that our solar panels will produce a total of 185,000 kWh, of which we should be able to reuse 140-150,000 kWh. We can sell the rest as a surplus. We should be able to reduce our need for purchased electricity by around 20% or more,” says Ronny Sjöborg, chairman of Brf Kabeludden, and is backed up by Lars-Erik Ahlf from Brf Kabeludden and Lars-Gunnar Börjesson, chairman of Brf Långbänken, who have managed the project together.
”The system has now been operational for two months. Of the five structures, we have monitored two of Kabeludden’s in particular. At the moment, it looks like the projections and reality are correlating surprisingly well. Production levels have tallied with the calculations we made in the project. We are happy to say that we have not found anything significant that could have been better managed. The project has progressed as planned, or even faster, and without disruption for our members. ÅF's representative Jakob Morelius has contributed to this to a major degree. All three of us have long experience of running businesses and projects, and we all agree that this is among the most well managed projects we have been involved with in our professional lives,” they add.