In India, the central Government, as well as the respective states, have laid out policies to encourage the adoption of solar energy. For many types of consumers, especially residential and commercial, the Levelized Cost of Energy (LCOE) of solar energy is lesser than the cost of energy imported from the grid. However, solar energy is an intermittent and variable resource, which cannot fulfil the load at all times. Addition of battery storage energy systems (BESS) to solar PV projects can help the consumer better meet their load profile through renewable energy, while improving grid resilience. In many states, time-of-day (ToD) tariffs are offered, which provide incentives for exporting energy beyond sunlight hours. It has been postulated that with ToD tariffs, and falling battery prices, addition of storage can provide benefits to the customer. However, it needs to be analyzed whether hybrid solarbattery storage configurations would make financial sense. In this study, we compare the performance of two popular battery types, Lead Acid and Lithium Ferro Phosphate (LFP), to see which battery type would provide better economic returns for the given customer. The impact of parameters like round trip efficiency, replacement State of Health (SOH), maximum State of Charge (SOC) and cycle time have been considered. It is shown that for current market tariffs and prevalent battery costs, addition of batteries does not improve the Net Present Value (NPV) for residential or commercial customers. The best returns are obtained when the system has only solar, with no batteries attached, while commercial systems achieve better NPV as compared to residential customers. The highest NPV for a residential customer is 1847 for a 6.6 kW system for the given load profile and tariff regime. In contrast, the highest NPV for a commercial customer is 4165 for a 7.7 kW project. It is seen that accelerated depreciation benefits play a major role in improved returns from commercial installations. It is also seen that retail rate dispatch provides higher returns as compared with the peak shaving and self-consumption dispatch algorithms, since it reduces both energy as well as demand charges. It is demonstrated how the retail rate dispatch modulates the battery discharge & charge configuration every hour considering the prevalent tariff at that time and the energy left in the battery.
Kumar et al. (Thu,) studied this question.