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BI PV Urban Scale Project Details
Name projectSolarsiedlung am Schlierberg, Freiburg (Breisgau), Germany
Year2006-06-00 (Start operation date)
PV applicationInclined roof - integrated: PV roof tiles
PV power total kWp
LocationFreiburg im Breisgau, Baden-Württemberg
Latitude/Longitude48°0'0"N 7°51'0"E
© www.architekturbuero-hagemann.de

Project summary
This solar settlement is part of a larger urban redevelopment in Freiburg. Over a period of approximately ten years 60 “Energy-Surplus-Houses®” and a 125 m service block, called “Sonnenschiff”, has been built. The “Sonnenschiff” provides retail-, office and living spaces. The terraced houses are two and three storeys high. The “Sonnenschiff” is four to five storeys high and thus screens the community from the traffic on Merzhauser Straße. All roofs are covered with large area Photovoltaic (PV) modules which are integrated in a plane above the south facing roofs of the buildings. With this project Rolf Disch wanted to provide evidence that his idea of an “Energy-Surplus-House®” works well for terrace houses and commercial buildings. He operated as the architect and as the entrepreneur of the Solarsiedlung am Schlierberg. This double function allowed him to ensure that his idea of so called “Energy-Surplus-House®” could be put into practice. At the same time he took a lot of personal risk to make this privately funded project happen and to provide the proof, that today’s homes are able to generate more energy than they need.

Urban scale PV aspects
The project follows a holistic approach of sustainable building design. Therefore it was important not only to design “Energy-Surplus Houses” but also to minimize the use of energy and environmental impact with regard to land use, utilization of public transport facilities, rainwater-use etc. The city planning for this district is done also in a way that all houses have sufficient access to sunlight in summer as well as in winter.

Special PV project info
PV architecture and building integrationThe project presents a simple but elegant solution for the mounting of the PV-Modules. Standard, semitransparent PV-laminates are integrated into a plane with an air-gap of 16 cm above the south facing roofs of the terrace-buildings. The PV-laminates are mounted point-wise on 30 mm RHS (rectangular hollow section) stainless steel profiles which themselves rest on hot-dip galvanised 100 mm I-beams. The water barrier of the roofs consists of a plastic-sheet sealing layer. Structurally, and therefore also legally, the PV-Array and roofing are two separate units. However, from the design point they are pleasant looking design feature of this settlement. In total 445 kWp of grid-connected PV is installed. The string inverters are mounted right under the roof deck on the building exterior walls. The total solar electricity production is 420.000 kWh.
Urban planning issuesIn 1990 French troops vacated a vast area south of the centre. The city of Freiburg bought the plot and started in 1993 a challenging urban renewable process for this area. The local city-planners remained responsible for the planning and development of the plot, located west of the Merzhauser Strasse, focussing on a sustainable development. However the target set for these buildings was not as ambitious as the plans for the “Schlierberg Solar Estate” from Rolf Disch. On the ground of the former sport facilities of the Vauban barracks, located on the east side of the Merzhauser Strasse, zoning regulations required a due south orientation for new buildings. This, together with the local infrastructure under development for the new Vauban district seemed to provide ideal conditions to realize the vision of an “Energy-Surplus-House®” standard on a district level.
Economical and financial issuesFinancial difficulties could be solved in by starting a fund, called “1. Solar Fond Freiburg”, with an invitation for subscription to shared certificates of € 5000 each. The total investment was € 1,5 Million. This new financing model was the key to success. The first one was followed by three other investment funds with a total investment of € 3 Million each. The purchase price for the terraced houses, including property and developers costs, ranged between € 2.700 / m2 and € 3300 / m2, depending on the individual fittings. In total 15 houses belong to these four solar funds. The houses are rented out for an average rent of €11 / m2. This corresponds to the upper price level in Freiburg. However normally surcharges for heating costs would need to be added. In this case they are negligible, since heating bills for each house are between 50 – 100 € per year.
PV ownershipThe roof integrated PV-systems are marketed separately from the terrace houses. Either the homeowners or other investors purchased them. A return of investment is granted by the 20 years payment of the feed-in-tariff of the German National Renewable Energy Act.
Tariffs and meteringFeed-in-tariff
This large scale PV-application was fostered by the German National Renewable Energy Act (Erneuerbare-Energien-Gesetz, EEG) which was implemented on 1 st April 2000. According to this law, grid operators have to pay fees for electricity from renewable energy sources. The difference between fees and the market price for electricity from traditional sources is apportioned to consumers via their electricity bills as EEG apportionment. The different types of renewable energy sources receive different fees based on the cost of electricity generation. This way of promoting electricity generation from renewable energy sources has proven to be extremely successful, in particular for wind power and PV.
Info on grid issues
Other infoOccupant´s Feedback In general occupants enjoy to live in the “Schlierberg Solar Estate“. They experience to have different benefits compared to occupants of conventional settlement. For example: - to enjoy to live in a solar home and to contribute to a resource efficient live style, - to benefit from the good inner-city location, - to have easy and short access to public transport facilities nearby, - to have an infrastructure appropriate for children (no cars etc.), - to feel less ill due to a healthier indoor climate/air quality and - to find the social environment they are looking for.
Remarks and recommended readingSources of further information including hundreds of different articles about the Schlierberg Solar Estate can be found on the following websites. Information are avaliable in German and partly in English as well. 1) Website of the Architect Rolf Disch: http://www.rolfdisch.de 2) Website of the “Energy-Surplus-House®” concept: http://www.plusenergiehaus.de 3) Website of the Solarsiedlung GmbH: http://www.solarsiedlung.de http://www.sonnenschiff.de 4) Website of the Solar Funds: http://www.freiburgersolarfonds.de http://www.sonnenschiff-fonds.de 5) Website of the City of Freiburg: http://www.solarcity-freiburg.de

Other project data
Type of projectCommercial project
Other relevant aspectsZero-energy house
Start of PV project
Start operation PV system2006-06-00
Main project leading companySolarsiedlungs GmbH
Main project contact personRolf Disch
Contact email
Contact addresshttp://www.solarsiedlung.de
Includes PV database projects

Urban district data
Kind of urban areaResidential - urban
Main building typesHouses - attached houses
New/Retrofit/AddedNew building integration
Main PV area address

PV systems
PV applicationInclined roof - integrated: PV roof tiles
PV power total urban project445 kWp
Number of dwellings/units60
PV power per dwellings/units0 kWp
Main PV system typesGrid-connected - demand side
Main PV module typesLaminates - regular laminate
Main PV cell typesCrystalline silicon - unknown other or mixed
PV module brand and typevarious brands and module types
PV inverter brand and typeSMA

PV cost and energy production
Total PV system investment
Average PV modules only costs
Total PV energy yield420000 kWh Calculated
PV energy user owner

Projects websitehttp://www.solarsiedlung.de
Other websites
Webpage Educational Tool


(PV) urban planning