Energy analysis of batteries in photovoltaic systems.: Part I:: Performance and energy requirements

The technical performance and energy requirements for production and transportation of a stand alone photovoltaic (PV)-battery system at different operating conditions are presented. Eight battery technologies are evaluated: lithium-ion (Li-ion), sodium-sulphur (NaS), nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lead-acid (PbA), vanadium-redox (VRB), zinc-bromine (ZnBr) and polysulfide-bromide (PSB). In the reference case, the energy requirements for production and transport of PV-battery systems that use the different battery technologies differ by up to a factor of three. Production and transport of batteries contribute 24-70% to the energy requirements, and the PV array contributes 26-68%. The contribution from other system components is less than 10%. The contribution of transport to energy requirements is 1-9% for transportation by truck, but may be up to 73% for air transportation. The energy requirement for battery production and transport is dominant for systems based on NiCd, NiMH and PbA batteries. The energy requirements for these systems are, therefore, sensitive to changes in battery service life and gravimetric energy density. For systems with batteries with relatively low energy requirement for production and transportation (Li-ion, NaS, VRB, ZnBr, PSB), the battery charge-discharge efficiency has a larger impact. In Part 11, the data presented here are used to calculate energy payback times and overall battery efficiencies of the PV-battery systems. (c) 2004 Elsevier Ltd. All rights reserved.