In this paper we present a simple, empirical model of stand-alone photovoltaic power system availability. The model is a final result of five-year long studies and ground measurements of solar irradiation carried out in Central Europe. The obtained results facilitate sizing of PV modules that have to be installed with taking into account system’s availability level in each month of a year. The model can be extended to different geographical locations, with help of local meteorological data or solar irradiation datasets derived from satellite measurements.
Photovoltaic (PV) technology is an attractive source of power for systems without connection to power grid. Because of seasonal variations of solar radiation, design of such a power system requires careful analysis in order to provide required reliability. In this paper we present results of three-year measurements of experimental PV system located in Poland and based on polycrystalline silicon module. Irradiation values calculated from results of ground measurements have been compared with data from solar radiation databases employ calculations from of satellite observations. Good convergence level of both data sources has been shown, especially during summer. When satellite data from the same time period is available, yearly and monthly production of PV energy can be calculated with 2% and 5% accuracy, respectively. However, monthly production during winter seems to be overestimated, especially in January. Results of this work may be helpful in forecasting performance of similar PV systems in Central Europe and allow to make more precise forecasts of PV system performance than based only on tables with long time averaged values.