A novel holistic metric for sustainability assessment of photovoltaic/battery systems

The increasing reliance on renewable energy has increased the need for efficient, sustainable energy systems, particularly photovoltaic (PV)-battery systems, which are vital for many applications in diverse climatic regions and directly contribute to SDG 7 (Affordable and Clean Energy). Achieving sustainability in such systems requires evaluating their performance across different locations and climatic conditions, where traditional metrics often fall short in capturing the complexities of energy utilization and battery behavior. This study proposes a novel holistic metric (HM) that incorporates battery performance, energy utilization, and load dynamics, providing a more accurate measure of system performance and supporting SDG 12 (Responsible Consumption and Production). The methodology involves the use of hybrid optimization of multiple energy resources (HOMER) software to simulate PV-battery systems in three locations, namely, Cairo, Berlin, and Riyadh, over a three-year period (2017-2019), with a focus on the battery state of charge (SOC), cycling behavior, and energy efficiency. The results indicate that Riyadh, with its balanced solar conditions, achieved the highest long-term viability (HM ≈ 0.74), followed by Berlin (HM ≈ 0.69) and Cairo (HM ≈ 0.67), with Cairo's oversized PV system and Berlin's low solar availability influencing battery performance and system efficiency. This study concludes that tailoring PV-battery system design and energy management strategies to local conditions is crucial for optimizing battery longevity, energy efficiency, and system resilience, addressing SDG 13 (Climate Action). The findings contribute to a more comprehensive approach for evaluating and improving the resilience of PV-battery systems, addressing gaps in conventional sustainability metrics.