The main function of solar panels is heating domestic-use water, however, due to the specificity of the climate in Poland, they are being used for this purpose practically only in the warm semester, i.e., from April until October. That is when approximately 80% of solar energy reaches the Earth’s surface (considering annual values). This means that practically only a fraction (approx. 40%) of energy generated by such an installation can be efficiently used.
Due to the periodic efficiency of solar panels in our climate, they are not used for heating the house. The power they produce in the heating season is simply not adequate. Because of this fact the rationality of such an investment depends mainly on the numer of inhabitants and the demand for hot water. As the payback period for this kind of investment is not short, this installations will generate the highest financial benefits (savings) in households with a high demand for domestic-use water which is heated with relatively expensive energy, e.g. fuels (such as heating oil and liquid gas) or electricity.