A building integrated photovoltaic system (BIPV) system may produce the same amount of electricity as consumed in the building on a yearly base. The simultaneity of production and consumption however needs to be evaluated: the distribution grid is regarded as virtual storage and is loaded unconventionally or even overloaded. A detailed bottom-up modelling approach of the domestic load, thermal installations and the local generation of BIPV system may give more insight. The present paper aims at quantifying the impact of domestic load profiles on the grid-interaction of BIPV-equipped dwelling in a moderate Belgian climate wherefore the cover factor is defined. For a yearly electricity production that equals the yearly domestic demand, a cover factor of 0.42 is found if a classic heating system is installed, denoting that more than half of the produced electricity will be passed on to the grid and withdrawn on another moment. If a heat pump is used for space heating and domestic hot water, the cover factor decreases to 0.29.