Load profile impact on the gross energy requirement of stand-alone photovoltaic systems

The sizing optimization of a Stand-Alone Photovoltaic system (SAPV) is a very complex issue. Therefore, a compromise solution must be made between having an acceptable energy and economic cost for the consumer, and a relatively correct energy supply quality. The Gross Energy Requirement (GER) of an SAPV system corresponds to the primary energy total amount required for the production, the maintenance and the recycling of this system. Reducing the GER is thus, an effective way to promote the development of SAPV systems. Therefore, the load profile management, in order to get closer to the ideal “solar” consumer, allows the downsizing of the system. In this paper, a methodology for studying the impact of load profiles on GER is proposed. Two different modifications parameters have been considered theoretically on idealized load and production profiles: the load shifting which seems simpler to implement in the reality, and the amplitude modulation. Furthermore, the NSGA-II genetic algorithm has been used to confirm theoretical outcomes and to optimize SAPV system sizing for three realistic load profiles, with the aim of quantifying the GER reduction, by minimizing the storage capacity (taking into account the replacements due to cycling) which is one of the weak points of such a system, and by PV panels downsizing.