Greenhouse Gas Emissions and Energy Payback Time for multi- and mono-Si Photovoltaic Systems - A Study on Solar Energy from Photovoltaic Systems Located in Sweden

Sammanfattning: Climate change is one of the greatest environmental challenges at the present time and is currently an issue affecting the entire global population. Alternative renewable energy sources are vital to be able to deal with this challenge. Solar energy is one of the most promising renewable energy sources and is therefore also one of the fastest growing industries in this field. However, solar energy has its downsides as well. During production of silicon based solar cells a large amount of energy is needed. In China, the world’s largest producer of Photovoltaic (PV) cells, this energy is produced mainly through burning of coal and therefore the production of PVs indirectly contributes to greenhouse gas (GHG) emissions. In this study two different methods were applied to evaluate the GHG emissions (g-CO2,eq/kWh) and energy payback time (EPBT) for monocrystalline (mono-Si) PV systems and multicrystalline (multi-Si) PV systems in five different places in Sweden; Malmö, Lund, Stockholm, Göteborg and Luleå. The results show that the EPBT range from 2.01 to 3.25 years and that the GHG emissions range from 63.05 to 102.02 g-CO2,eq/kWh depending on the method applied, which type of PV system that was used, and the solar irradiation. Based on this study, energy from photovoltaic power could potentially be a part of the solution for Sweden’s future energy demands. However, this depends on several different factors. The location of the PV system is of great importance as well as the direction and angle in relation to the sun. Also, the development of the PV cell’s efficiency plays a major role in the future EPBT and GHG emissions from solar energy. This study was based on estimations from previous studies and therefore the results could contain some uncertainties.