Design of hybrid-photovoltaic power generator, with optimization of energymanagement

A methodology is developed for calculating the correct size of a photovolta ic (PV)-hybrid system and for optimizing its management. The power for the hybrid system comes from PV panels and an engine-generator - that is, a gas oline or diesel engine driving an electrical generator. The combined system is a stand-alone or autonomous system, in the sense that no third energy s ource is brought in to meet the load. Two parameters were used to character ize the role of the engine-generator: denoted SDM and SAR, they are, respec tively, the battery charge threshold at which it is started up, and the sto rage capacity threshold at which it is stopped, both expressed as a percent age of the nominal battery storage capacity. The methodology developed is a pplied to designing a PV-hybrid system operating in Corsica, as a case stud y. Various sizing configurations were Simulated, and the optimal configurat ion that meets the autonomy constraint (no loss of load) was determined, by minimizing of the energy cost. The influence of the battery storage Capaci ty on the solar contribution is also studied. The smallest energy cost per kWh was obtained for a system characterized by an SDM = 30% and an SAR = 70 %. A study on the effects of component lifetimes on the economics of PV-hyb rid and PV stand-alone systems has shown that battery size can be reduced b y a factor of two in PV-hybrid systems, as compared to PV stand-alone syste ms. (C) 1999 Elsevier Science Ltd. All rights reserved.