Abstract
•Deriving the optimal size of solar and battery systems is of great practical importance.•Economic and reliability factors are crucially interacting in energy systems design optimization.•In critical applications, the economic losses of lost demand can be severe and need to be minimized.•The anticipated decline in battery price brings optimism for more widespread usage of backup systems.
This paper investigates the trade-off between two critical factors that influence, or even dictate, the rate of adoption of battery systems used to support photovoltaic arrays. The value of lost load and battery price greatly influence the island mode generation capability and the economic viability of photovoltaic + battery systems to provide energy resilience during grid outages. Photovoltaic array systems combined with battery storage are increasingly important to assure reliable and resilient power supply. It has been found that the configuration of photovoltaic + battery systems, which determines their capability of operating in island mode in response to grid outages, is impacted by multiple factors. Recent industry reports and research work have highlighted the critical role that energy storage systems will have in the coming future in the electricity sector, especially when combined with renewable energy systems. The fact that forecasts predict a sharp decline in battery price not only strengthens this role but also makes the need for extensive research in this area more important. A simulation-based optimization method is developed to investigate the effects of value of lost load and battery price on the balance between total system cost and system islanding resilience to meet customer demand during a grid outage. According to actual solar irradiation data and the load profile of a hospital, a case study is conducted in which evaluation metrics are computed and compared from both resilience and economical aspects. The underlying relationship between the changes and uncertainty of value of lost load and battery price are explored by comparing the optimal total system cost under two distinct scenarios. The results provide us with guidance and insights regarding the impact of cost-related factors on photovoltaic + battery system design to make them grid-outage resilient and economically viable. Moreover, this work illustrates the positive effect that the anticipated decline in battery price will have in enhancing the resilience and effectiveness of renewable energy systems combined with energy storage.