Optimisation of residential solar PV system rating for minimum payback time using half-hourly profiling

Abstract

There is increasing interest in the residential load sector in the installation of grid-connected solar photovoltaic (PV) renewable energy sources as means to reduce the cost of electricity imported from the grid. The research presented here proposes a mathematical model used with a direct search methodology to optimize the rating of a solar PV system, with the view to minimize payback time, for a residential system with given load profile. Half-hourly average energy profiles are used to model the solar generation profile and load profile. Results are presented for two case studies, using a representative daily solar generation profile and daily residential load profile. The case studies include determining the optimal PV system rating, i.e. with minimum payback time, for a system with a fixed load profile and for a system where load scheduling optimization is applied. The results show, that in each case, the direct search optimization algorithm can quickly determine the PV system rating with the minimum payback time. The effects of the load profile and solar generation profile characteristics on the payback time are explored using the concept of a solar utilization factor. It is shown that the utilization factor plays a critical role in improving payback time.