Assessment of lithium ion LiFePO4 cells usage in photovoltaic standalone systems

Since the emergence of photovoltaic powered systems, lead/acid batteries have been the preferred energy storage solution thanks to their low price and high robustness to abusive operation. However, limited shelf-life and low energy density are two important drawbacks of this technology which hinder the development of very small scale photovoltaic standalone systems. Novéa Énergies is a French manufacturer of such systems used for lighting of off-grid isolated areas. In partnership with the French National Institute for Solar Energy (INES) and the Institute of Electronic and Telecommunications of Rennes (IETR), this project aims to develop an alternative energy storage system economically competitive while exhibiting a better lifespan and energy density. We show in this paper that lithium ion (Li-ion) technology and particularly cells using lithium iron phosphate (LiFePO₄ - LFP) cathode material, exhibit pricing and robustness features which make them a viable alternative to Valve Regulated Lead/Acid (VRLA) batteries which are mainly used today in small photovoltaic standalone systems.