General information Location: Bale, Switzerland Sunshine hours (yearly average): 3,6 hours per day Type of project: Flat roof, SOLGREEN system Type of application: Retrofit Time for design process: 2 months (incl. electrical engineering) Time for construction: 3 weeks Realization: September 2000 [ Top ] Description Within the frame of the new Solarstock exchange by the power utility of Bale, a PV power plant was built on a school house, using the new SOLGREEN system. In total 216 BP Solar 580 laminates were installed onto 300 m2 roof. Resulting in a total capacity of 17,3 kWp installed power. The existing flat roof of the school house was built as green roof, extensive vegetation is growing. It was demanded that only little additional weight is placed onto the roof. This required a new solution for the substructure. A light-weight system, which is fixed by the gravel foundation of the roof and the substrate for the green roof vegetation. An important design issue was further to give as much space over ground as possible, because of the ground vegetation growing up to 40 cm and the required roof maintenance for a green roof, e.g. grass mowing. Due to the very easy access to the PV installation and good insight, an elegant mounting system was asked by the building department of Bale. The system should be easy to mount (less construction work), cost- effective and should have a good appearance. SOLGREEN is a new mounting structure for PV modules and laminates especially developed for green roofs. It is a light- weight system, which adds almost no load to the green roof. The structure is fixed by the gravel foundation of the roof and the substrate for the roof vegetation. Thanks to this approach solar arrays can be combined with vegetated roofs in an economical and aesthetically pleasing way, that met with an interesting new and elegant design for flat roofs. However the drawback is higher cost for the specific production technique of the design and the materials used. The applied SOLGREEN system is available in two versions (large and small) and has an inclination angle of 30°. [ Top ] System characteristics PV system power: 17,3 kW Type of building integration: Flat roof, but green roof application Type of cell technology: Mono crystalline Module dimensions: 520 * 1118 mm Array dimensions: 16 m * 25 m => 400m2 Inverters: String inverters 6 SunnyBoys 2500 BOS components: SOLGREEN mounting structure [ Top ] Project cost breakdown Solar modules: € 71 840 Inverters: € 13 450 Mounting system SOLGREEN: € 29 760 Mounting: € 11 520 Electro installation: € 5 820 Planning, Design: € 15 850 Miscellaneous: € 5 470 Total cost: € 153 710 [ Top ] Performance characteristics A total power production of 14 500 kWh per year was calculated. The inverters and the modules work well so far, meeting the expectations. The building performance has not being changed by the PV installation. [ Top ] Project team Client: Edisun Power AG Project architects: Enecolo AG Engineers:Enecolo AG Contractor: Energieprojekte Kottmann PV manufacture: BP Solar [ Top ]