Large Grid-connected Hybrid PV System Integrated in a Public Building A. Lloret, 1 J. Andreu, 2 J. Merten, 2, * J. Puigdollers, 2 O. Aceves, 3 L. Sabata, 3 M. Chantant 4 and U. Eicker 5 1 Laboratoire de Physique des Interfaces et des Couches Minces (UPR-258 CNRS), Ecole Polytechnique, F-91128 Palaiseau Cedex, France 2 Departament de FõÂsica Aplicada i Optica, Universitat de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Spain 3 TFM SA, Poligon Ind. Pla d'en Coll, c/ Gaia Á 5, E-08110 Montcada i Reixac, Spain 4 GENEC, C. E. Cadarache. Ba Ãt 351, F-13101 Saint Paul-lez-Durance, France 5 ZSW, Hessbru Èhlstr 216, D-70565, Stuttgart, Germany This paper describes the integration of photovoltaic (PV) cells into a public building, the public library `Pompeu i Fabra', which is located in Mataro Â, a Mediterranean town close to Barcelona, Spain. For this purpose, standardized building elements have been developed that provide both thermal and photovoltaic energy from the sun. These hybrid PV±thermal modules are prefabricated and then quickly mounted on the building as a curtain wall. The ®rst data on the electrical performance are presented. Back ventilation of the solar cells in the hybrid PV±thermal modules leads to increased electrical performance of the PV generator. # 1998 John Wiley & Sons, Ltd. PHOTOVOLTAIC SYSTEMS AND THEIR INTEGRATION INTO BUILDINGS P hotovoltaic (PV) systems are one possible option to reduce the CO 2 emissions usually associated with the generation of electricity. Installing these systems in the ®eld requires the development of a structure to support the PV modules. Their integration into buildings reduces the area-related costs of the PV system and allows their installation in urban areas. In this paper, we present the integration of a PV system into a public library building, which enhances its aesthetic and architectural quality (Figure 1). Building-integrated PV systems displace conventional building materials, leading to cost reductions, and improve the image of the building and its users (`green', `high tech', self-sucient). Because the electricity is generated in situ, building-integrated PV systems may lead to an increased security of uninterrupted power supply (UPS) systems. Integration of PV systems into buildings does not mean that the PV modules are simply plugged onto the building structure; in this case no important cost reductions can be obtained. Aesthetically more satisfying is the integration using cladding elements 1 or shading elements covered with PV modules. 2 In this case, the PV modules ful®l two functions: they produce solar electricity and also absorb the solar radiation, thus reducing the heat transfer into the building. Hybrid PV±thermal modules make use of the thermal energy absorbed in the winter, but still provide shading in the summer. One of the ®rst examples is the factory building AERNI in Switzerland (built in 1991). 3 The thermal energy obtained by ventilation of the back of the PV module is used directly in the winter and stored in the summer for retrieval. CCC 1062±7995/98/060453±12$17 . 50 Received 2 January 1998 # 1998 John Wiley & Sons, Ltd. Revised 8 May 1998 PROGRESS IN PHOTOVOLTAICS: RESEARCH AND APPLICATIONS Prog. Photovolt. Res. Appl. 6, 453±464 (1998) Applications *Correspondence to: J. Merten, Department of Applied Physics and Optics, University of Barcelona, Av. Diagonal 647, E-08028 Barcelona, Spain. E-mail: jmerten@fao.ub.es