The increase in demand for electricity in recent years in Albania has become evident. On the other hand, the sensitivity to sustainable and environmentally friendly development has also increased. In this way, the focus of electricity production is oriented to renewable sources, especially by installation of photovoltaic farms. So, in recent years, several photovoltaic farms with considerable power have been installed in Albania. The installation of photovoltaic farms, in addition to the advantages that are known, also brings problems to the electrical system. In this paper, the system penetration of power produced by photovoltaic plants will be analyzed. The analysis of the energy system was initially done in established regimes where the distribution of power flows, losses in the system as well as voltage levels in the nodes of the energy system were done. The analysis developed in this paper shows that the penetration of a significant amount of energy from photovoltaic plants into the system worsens both the voltage levels in its nodes and the dynamic stability.