This paper aims to show the profitability of photovoltaic power plants without incentives. This paper presents the basic concepts of the photoelectric effect, as well as a general overview and principles of operation of photovoltaic cells. Photovoltaic power plants are described, which can be classified into two basic categories. It is shown what costs of a photovoltaic power plant can be expected in terms of investment, maintenance and other costs. The method of examining the profitability and return period of the investment in the power plant itself is described. Also, a presentation of expressions with the help of which it is possible to calculate the profit for a customer of a network with its own photovoltaic power plant is given. The paper provides an analysis of the profitability of photovoltaic power plants without incentives with an emphasis on examples from practice. In the above examples, attention is paid to determining the required payback period for the investment in the photovoltaic power plant.