The Swedish energy system will be influenced by many future changes, such as energy and climate policy objectives. The installation of more renewable electricity could increase by using solar energy. Over the recent years, grid-connected photovoltaic (PV) systems have increased dramatically in Sweden, partly due to various support systems and compensation models. These support systems have been designed to make it easy for individuals and businesses to invest in self-generated electricity and thus contribute to the transformation of the energy system. The introduction of a higher proportion of solar energy may in turn affect the Swedish electricity system. This could mean that the electricity companies will be facing a number of changes in the near future. Some distribution system operators that may be affected by a significant installation of small-scale PV systems are the companies in the association Elinorr. The association consists of sixteen local independent electrical network companies operating in southern- and central Norrland. The purpose of this master thesis has been to conduct a study of how the potential of a major installation of small-scale PV systems may affect Elinorr. To achieve the purpose, the following questions have been answered: Which support systems and compensation models creates the greatest incentive to install PV systems in the Elinorr grids? How long is the payback period for electricity consumers who choose to install a PV system? Which compensation models are used by the member companies within Elinorr? How would the grids in Elinorr be affected by the introduction of many small-scale PV installations? The result shows that 56 smaller PV-systems were connected to Elinorr in April 2013. Half of the members companies are using the compensation model developed within the association. For a small-scale producer to exploit the various support systems, it must be active and at the right geographic location. Support systems and compensation models also have a big impact on the payback time for a small PV system. The best outcome for a larger PV-system has a payback time of 8.2 years and for a smaller system, it takes 11.5 years before it is repaid. A limited amount of PV installations can affect the local distribution network in a positive way, giving lower electricity losses and improved voltage levels. A high level of PV penetration may affect the local distribution networks, so that the electricity companies have to increase the capacity.