The world's largest building integrated project began operation in March. The one megawatt PV system is integrated into roof and façade of the Academy Mont-Cenis Herne. It combines modern architecture with an innovative PV concept.

The opening ceremony of the spectacular building of the new Academy of Further Education of North-Rhine Westphalia will take place on August 20th. The building's enormous glass envelope measures 180 m by 72 m by 16 m and contains offices, a library, a hotel and other facilities such as a restaurant. The envelope produces a microclimate, transforming the former coals mining site into a 'Mediterranean area' enabling users to walk 'outside' under the glass roofing alongside plants and a pond. 3 184 Pilkington Solar OPTISOL® PV elements, which use a glass-glass encapsulated technique, are integrated into roof and façade elements, to provide shading, day-lighting and electricity production. The total roof area is around 12 000 m2 which presented a challenge to the roofing and PV system designers.

The final solution, which looks like a cloud-patterned sky, uses six different types of modules with different densities of solar cells and glass of various degrees of transparency. The number of cells per module ranges between 260 and 128 - with corresponding power outputs of between 419 and 250 Wp) from the roof areas above the inner buildings to the middle and edges of the roof where more daylight is needed. The inverter concept is innovative for a project of this size. 569 string inverters are used in order to reach the highest system efficiency for the complicated module distribution on the roof. Installation of the inverters only took about three months in total; two weeks each to install the frames and fix the inverters into position, and a further two months for cabling. The advantage of this arrangement is that each string has its own MPP-tracking and is connected to a central computer, which shows not only the total power off the PV generator but also the working condition and power of each string. It is possible to check the whole PV system with one glance at the computer screen.

Energy production is expected to reach 750 000 kWh per annum, which is approximately three times more than the building will consume each year. The results of the first few weeks operation have been very encouraging with production reaching 49 000 kWh in March and peak system power exceeding 500 kWp.

The overall installed cost of the system was DEM 14,7 million. A cost of about 8,5 USD/Wp for a system that is roofing, façade, shading and solar generator in one. It was financed 49% by the state of North-Rhine Westphalia and the EU, with Stadtwerke Herne, the local utility company, investing the remaining 51%.

Information

• Eric Schaar-Gabriel
  Pilkington Solar International
  Fax: +49 221 258 1117.

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