The studies were carried out in order to propose a criterion for the technical and economic assessment of photovoltaic systems layout options, which allows providing consumers with electric energy at a cost lower than the current tariff in the Unified Electric System, and meeting the requirements for the payback of projects in the energy sector. The theoretical basis for the search for an economically viable option for the layout of the modules of the photovoltaic system was the mathematical formulation of the optimization problem using the following criterion: the cost of generated electrical energy is lower than or equal to the current tariff of the power system for consumed electrical energy. At the same time, the requirement that the payback period of the project does not exceed the standard value of 8 years was taken into account. On the example of a processing agricultural enterprise located in Rostov region, taking into account the peculiarities of its development and the regime of insolation of the territory, consumers were identified, on whose roofs it is possible to install photovoltaic systems. The mode of operation involves generation within the power supply system of the enterprise without generation beyond the point of balance. The analyzed changes in the technical and economic indicators of a photovoltaic system with an increase in its power, if the latter operates with the accumulation of electric energy and taking into account the load schedule, made it possible to identify that 5 photovoltaic systems with a maximum power of 0.4 kW to 71 kW of total installed power can be installed on the territory of the enterprise. with a power of 77.4 kW. But only for four of them the proposed criterion is met: the payback period is not more than 8 years (5.7 ... 7.4 years), and the cost of generated electrical energy (4.0 ... 5.5 rubles / kWh) is lower than the current tariff (8.3 rubles/kWh). The excess of electricity generation by photovoltaic systems, compared to the load of consumers on the roof of which they are located, is directed to the power supply system of the agro-industrial complex for the power supply of other consumers, which makes it possible to realize the solar energy resource to a greater extent at the geographic location of the object.