Can solar plus storage keep the lights on? Assessing solar plus storage for backup power during long-duration power interruptions in the US

Recent market trends reveal rapid growth in the adoption of paired behind-the-meter (BTM) solar photovoltaic and energy storage systems (PVESS). Those trends have been driven in part by customer concerns over electric system reliability and demand for backup power, which are likely to become even more pronounced as wildfire, hurricane, and other climate-driven risks rise over the coming decades. But what can customers expect, and what can installers promise, in terms of how well these systems might actually perform in providing backup power during long-duration power interruptions? The presentation will highlight key findings from Berkeley Lab' examination of BTM PVESS in backup power applications. The analysis is based on simulating PVESS backup performance during both a set of synthetic power interruption events as well as a set of 10 historical long-duration power interruption events. The analysis evaluates performance across a wide range of outage conditions and across thousands of individual building models, capturing both different building types and variations in the existing building stock. The results show how even a relatively small PVESS can provide backup power to a basic set of critical loads, while also highlighting some of the key considerations and constraints in providing backup to electric heating and cooling loads. The analysis illustrates both the challenges and opportunities associated with electrification, in terms of PVESS backup power capabilities.