4. Conclusions
In this study, the performances of grid-connected PV systems, for a residential building in Oslo with a 100 m2
flat
rooftop, were investigated using PVsysts. The site location has average solar radiation of 987 kWh/m2
on a
horizontal surface. The study showed that PV modules’ row spacing in the array and their tilt angles should not be
neglected when designing grid-connected PV systems for rooftop. Moreover, with the current price of electricity and
the low level of financial support from the government, grid-connected PV systems are not financially profitable,
particularly if we consider the fact that the PV system would cover the residential building’s annual energy
demands. From an environmental point of view, the m-si PV module would emit a maximum of 69 g CO2/kWh in
its 30 years of operation, with an energy payback time of 3.9 years