Lithium-ion battery based renewable energy solution for off-grid electricity: A techno-economic analysis

Small renewable energy solutions such as solar home lighting system (SHLS) provide reliable electricity supply to off-grid bottom-of-pyramid (BoP) households and thereby improve status of living. Commercial SHLS employs polycrystalline silicon photovoltaic (PV) and flooded lead-acid battery technologies for energy generation and energy storage, respectively. Flooded lead-acid battery is a 150-year-old, mature and inexpensive energy storage technology but has a short lifetime. In SHLS, flooded lead acid battery requires replacement every 4-5 years and can cost up to 70% of the total cost over the 20 years lifetime of the system. In this paper, seven advanced lithium-ion battery chemistries were evaluated as a potential replacement for flooded lead acid battery in SHLS using HOMER microgrid software. Three lithium-ion battery chemistries NCA, LFP and LFP/LTO - were found to be viable alternatives based on economic and performance metrics. The three lithium-ion battery based SHLS showed comparable initial capital cost to that of the commercial SHLS but provided significant advantage over the system lifetime as no/fewer battery replacements were required, which resulted in a total net present cost (TNPC) that was as low as 45% of the commercial SHLS. Price of lithium-ion battery technology is decreasing at 8-16% annually in real terms and the cost advantage of SHLS based on lithium-ion battery is expected to increase significantly in the future.