For an exemplary single-family residential building, final energy consumption for heating and domestic hot water preparation was calculated using an air / water heat pump, consumption of electricity for household purposes (lighting, household appliances, RTV, etc.) was also calculated as based on statistical summaries. On this basis, power was selected and the annual production volume was determined by a photovoltaic micro-installation working in the ON-GIRD system pursuant to prosumer regulations contained in the Act on Renewable Energy. Then, an economic analysis was carried out basing on such static and dynamic methods as SPBT, PBP, NPV, IRR and CCE. The calculations were made for two variants, i.e.: the investment costs of the system are borne entirely by the investor, or the installation is purchased within the "EKOkredyt Prosument II" NFEP&WM program. As a result of the calculations, it was found that the investment in PV microinstallation will be profitable only if the support instruments offered by the NFEP&WM program are used. If the investor uses co-financing, the investment will pay back within 16 years at the latest and if he wants to invest his own funds, the waiting period for the return on investments can be extended to up to 21 years, which, given the twenty-five year period of operation, can turn out to be the risk that the funds invested can never be returned.