Comparison of typical meteorological year and multi-year time series of solar conditions for Belsk, central Poland

The deployment of solar energy projects in a given region requires a precise estimation of potential solar resources. For that purpose, generating a typical meteorological year is of great importance, although in principle it is a tool used in construction or engineering. Various methods for deriving typical meteorological years have been developed, but their final results can be significantly different. In this paper, two major methodologies (TMY3 method and ISO 15927-4 standard) were applied to 12-year measured data series recorded during the period 2003-2014 in Belsk, central Poland. The sums of global solar radiation obtained in typical meteorological years were compared to the long-term average measured sums of global solar radiation in order to decide which method can be recommended as best reflecting solar conditions in Poland. According to this study, the differences between the respective TMY data sets and long-term measured data set (measured with percentage root mean square error - %RMSE) are bigger than 5%. ISO 15927-4 standard slightly better approximates solar conditions in central Poland than TMY3 method - the %RMSE equals 5.25% and 6.71% respectively.