En solklar taklösning: En fallstudie på synergieffekter av bifacialsolceller och extensiva gröna tak

Sammanfattning: The master thesis has evaluated the specific combination of bifacial solar cells and extensive green roofs. This was done in terms of energy production per year, profitability as well as discussions around ecosystem services. Three cases have been simulated with different temperature profiles for both bifacial, vertical bifacial and monofacial. The reason for three cases was due to the uncertainty in temperature decreasing properties of vegetation i Sweden. One case was simulated for a normal black bitumen roof for the three types of solar PV. The result with the best energy production was found in the configuration with azimuth -10o, inclination 40o and height above roof at 40 cm. This was the case with the largest simulated temperature decrease. Albedo was set to 0.2 and this resulted in a bifacial gain of 9-10% for the three cases with green roofs installed. Albedo was found to be a larger factor in the energy production outcome than the temperature decrease from the vegetation. The solar cells contributes to shading the green roof partially which increases the local biodiversity as well as expands the lifetime of the vegetation. The combination was deemed profitable since the middle case had an annuity of 1841 SEK/year, but the case with the bitumen roof was found to be even more profitable with an annuity of 4160 SEK/year. This indicates that the extra cost of installing a green roof does not pay itself back with a higher energy production.