Over the last decade, as a result of a pro-ecological policy of the EU, there has been a rapid development of renewable energy. Unfortunately, legislation, which should ensure the safety of the expanding and developing power system, cannot keep up with the technological development. There is a need for serious and insightful analysis on the impact of distributed generation on the power system. The article shows possible adverse effects of the source on the power network parameters while meeting the conditions contained in the applicable standards and regulations. On the example of the chosen photovoltaic farm, there has been shown a negative impact of the source on the power quality parameters, based on the methodology of research in accordance with the applicable standards and based on the analysis of the results. The paper presents possible problems and risks associated with the described issue that may arise in the future with the further development of renewable energy sources.