Theoretical study of the potential to improve indoor comfort in Botswana using solar water heating, solar PV and PV/T

Abstract: The possibility of improving indoor climate in residential buildings in Botswana was examined as the foundation of this Master’s Thesis. Initially articles were studied to gain understanding of previous research in the field as well as to gain understanding of local energy related conditions. Furthermore, a software called TRNSYS was thoroughly studied as this was found to be a powerful tool able to perform wanted simulations. Through two months of field work the previously obtained parameters for the simulation were complimented with on sight observations, mostly of residential buildings. This provided the foundation to initiate actual simulations. It quickly surfaced that the way residential building are built in Botswana today did not allow for space heating or cooling as the current houses have an average U-value of 2.9 W/(m^2·K). It was found that with an average U-value of 0.5 W/(m^2·K), no space heating of any type is needed. However, as this meant warmer indoor climate during summer, the possibility of generating electricity to power AC units was studied. Two systems to solve this were studied and compared. Firstly a solar collector in combination with photovoltaics (PV) and secondly a hybrid PV/T system to generate both hot water and electricity. A 13.35 m^2 solar collector in combination with a 2 m^2 PV generated approximately the same amount as a 13.35 m^2 PV/T system, resulting in 84 % of the energy need being derived from solar energy assuming a household consumption of 5000 kWh.