The aim of the study was an assessment of the economic efficiency of photovoltaic micro-installations. The research was carried at 5 objects Roztocze National Park. At current prices of electricity and functioning support system of production from renewable energy sources (RES), the investment in the photovoltaic systems have little economic justification. The expected payback period was in the range of 18 to 40 years, and only two systems was less than the anticipated exploitation period of 25 years. The article presents the results of the simulation account the profitability of the installation of up to 10 kWe, assuming that electricity is produced in the prosumer systems. Then payback contain from 14 to 21 years took on a NPV value greater than 0.