Comparison of lead acid and Li-ion battery in solar home system of Bangladesh

Different technical issues regarding the use of Li-ion and lead acid battery in solar photovoltaic system is presented in this study. Economic comparison for using these two types of batteries in solar home system (SHS) of Bangladesh is also presented in terms of net present cost (NPC). Li-ion batteries, especially LiFeSO₄ batteries, are technically more advantageous for use in intermittent solar photovoltaic system than conventional lead acid battery. Fast charging rate, high energy density, extended cycle life, low maintenance are advantages of Li-ion batteries compared to lead acid batteries. At present main disadvantage of Li-ion batteries is its high capital cost. From HOMER (an micro-grid simulation software) it is found that instead of high cycle life and maximum depth of discharge (DOD) of Li-ion batteries than lead acid ones, NPC of SHS with Li-ion battery is higher than that of system with lead acid battery if project lifetime is less than 5 years. For project lifetime greater than 5 years, NPC of Li-ion based system is comparable to lead acid system. Moreover, for small size of systems using Li-ion batteries in SHS is economical than lead acid batteries. As system size increases, use of Li-ion battery in SHS becomes costlier than lead acid battery. Environmental effect of two considered types of batteries is also discussed here.