Recently, there has been a significant surge in the utilization of renewable sources for generating electricity. This growth has been so rapid that it can be described as almost exponential. As a result, numerous entities and organizations have become energy prosumers. When a specific energy source is linked to the power grid and interconnected with another energy source, we speak of hybrid systems, and we know that hybrid systems’ behavior deviate from the behavior of each individual system connected to the network. This paper analyzes a case study consisting of three photovoltaic systems of different powers and with different equipment characteristics (two of them), connected both to the national electricity power-grid and a to a diesel-generator group. We examine the electricity generation and usage of the complete photovoltaic system throughout a one-year time span. Subsequently, we assess the impact of the hybrid system on the power network during notable fluctuations while in load operation mode. The analysis shows that, over the period of one year, the photovoltaic system provided for 32.31% of the industrial user’s energy consumption. Considering the energy injected into the grid, the energy generated by the photovoltaic system accounts for 42.21% of the user’s total energy usage. Upon reviewing the data, we found that the photovoltaic system linked to the grid fails to meet the necessary quality standards concerning fluctuations in voltage supply.