Carbon footprint optimization for a large-scale PV on-grid System in Borlänge, Sweden

Abstract: The aim of this master thesis is to design and analyze a photovoltaic (PV) system with the smallest possible carbon footprint. The system will be located in Borlänge, Sweden near the airport. The main components the analysis will focus on are the modules, inverters as well as the cabling. For that, different technologies like thin film and crystalline silicon cells will be compared with each other in order to find out how much the energy consumption in production differs. Since carbon emissions depend on the electricity mix, the manufacturer will also be included in the analysis. That way, manufacturers that use highproportions of renewable energies can produce products with a small carbon footprint, even if the energy demand is comparatively high. The last phase, will focus on factors such as warranties, because longer lifetimes also help to reduce the carbon footprint. For the analysis two software are used. The Granta EduPack, which has data on the carbon emissions for different materials and therefore is used to estimate carbon footprints for some of the components. As well as PVsyst, a software to simulate PV projects. It is used to scale the components and also to get an estimate for the annual yield and its deviation. The analysis finds that even in Sweden, a carbon footprint (CF) of just 14 g/kWh can be achieved. This value is 70 percent below that of today's average utility scale PV system. Considering the margin of error, it is assumed that this value could be as low as 11 g/kWh under optimal conditions and up to 23 g/kWh in the worst case. This puts the CF in the same range as on- and offshore wind power. For better suited locations such as near the equator, this value could be more than halved. With these values, PV is already one of the lowest emitters of greenhouse gases (GHG) among power generation technologies. It can be assumed that these values will continue to fall. Due to process optimization and an increase in efficiency, the carbon footprint of both modules and inverters is reducing steadily. This thesis is written in cooperation with two Energy Efficient Built Environment (EEBE) students, who in addition analyze the mounting structure of the system. The aim for the mounting structure is to have a low carbon footprint as well. Their results on the different structural materials are integrated in the conclusion.