Feasibility Analysis of Different Energy Storage Systems for Solar Road Lighting Systems

This paper investigates and analyses the feasibility of different energy storage systems for solar road lighting systems. The energy storage systems used in this paper are divided into two cases, namely, homogenous energy storage system [lead-acid (LA) batteries, lithium-ion (LI) batteries, and ultracapacitors (UCs)] and hybrid energy storage systems [lead-acid batteries with ultracapacitors (LA and UC) and lithium-ion batteries with ultracapacitors (LI and UC)]. Various solar power schemes are implemented based on stable and unstable solar irradiance conditions using an experimental setup. The economic analysis of the solar road lighting systems is performed based on the presented energy storage systems using discounted payback period (DPP), net present value (NPV), and internal rate of return (IRR). The installation of energy storage systems with individual and central systems for the solar road lighting system is also discussed. The results show that the LA batteries, LI batteries, and UCs yielded satisfactory active power quality for effective charging in all ranges of solar irradiance. However, the lifetimes of battery devices are degraded during dynamic active power charging. To overcome this shortcoming, hybrid energy storage systems are proposed using batteries and UCs. The use of LA batteries yields the lowest installation cost. However, the LI batteries offer the best economic viability in the long term. The cost of the UCs is too high to be used as an energy storage system for solar road lighting systems. However, the use of appropriate proportions of the UCs with batteries to reduce current and active power fluctuations for charging the batteries is economically viable.