The market for photovoltaic systems is rapidly expanding. Currently, there are a few large utility photovoltaic power plants, thousands of residential systems, and tens of thousands of remote power systems in use. Even if photovoltaics is a technology that has already demonstrated its effectiveness and holds great promise in electrical generation, the costs are still too high to guarantee a commercial competitivity. The study presented in this paper is part of a European XVII Thermie project entitled "Pilot project for photovoltaic, energetic and biohousing retrieval in a school", the aim of which was to install a photovoltaic plant and solar air collectors coupled with a sun breaker structure at a scientific high school in Umbertide, in central Italy. A 15 kWp photovoltaic power plant was mounted on the roofs of two blocks of the school building in spring 2001. The system consists of 220 modules for a total of 22 arrays, which are connected to inverters to allow conventional appliances to be powered by photovoltaic electricity. The photovoltaic plant is remotely controlled and data on sun radiation, ambient temperature, modules temperature and power production are continuously acquired by a PC. The measured power plant performances during the year are presented in this paper. Furthermore, the climate in the area has been simulated through the available experimental data and the system behavior under these conditions is predicted. The experimental data have been used to validate a predicting numerical model for photovoltaic plants performance. (C) 2003 Elsevier Science Ltd. All rights reserved.