With the growing popularity of solar cells in Sweden, real estate companies have become interested in the possibility of installing solar panels when constructing new apartment buildings. Riksbyggen is one of these companies that sees solar energy as an interesting alternative when constructing energy-efficient buildings with low energy consumption. The purpose of this study is to investigate optimal system solutions and the profitability of a PV-system in a newly produced apartment building containing 28 apartments in Västerås. This investigation is made possible by creating and simulating the PV-system in the simulation program PVSyst. The PV-system that will be installed on Brf. Sjökortet has an installed capacity of 54 kW. 40 kW will be placed on the roof with a tilt of 4° while 14 kW will be placed on the facade with a tilt of 90°. According the simulation results, the PV-system will produce 43,6 MWh per year, which means the specific electricity production becomes 807 kWh/kWp. Own use of solar electricity is estimated to be 61 %, which means that 26,7 MWh will be utilized directly by the housing association, while 16,9 MWh must be submitted for sale. Out of the solar electricity that can be used directly 9,9 MWh will cover the property electricity meanwhile the remaining 16,8 MWh covers the residents household electricity. The residents of the housing cooperative will thus gain access to a large portion of the produced solar electricity without having to pay for it. The PV-system will without investment aid become unprofitable with an annuity of – 16 304 SEK per year. When the investment aid covering 35 % of the investment cost is included, the PV-system becomes profitable with an annuity of 2 687 SEK per year. The own use of solar electricity is difficult to improve by only changing the tilt of the solar panels. However, the results shows that a greater amount of solar electricity can be utilized by the housing cooperative in the winter months by increasing the amount of solar panels on the facade while decreasing the amount of solar panels on the roof with the same amount. A higher amount of solar panels on the facade will though decrease the yearly solar electricity production, making it more difficult for the PV-system to show profitability. The determined distribution of solar modules on the roof and facade is optimally distributed if the goal for the housing association is to utilize as much solar electricity as possible directly.