Solar and Resilience Basics

What Is Electric Power Resilience?
A resilient power system, as defined by the U.S. Department of Energy (DOE)’s Grid Modernization Initiative and the National Academy of Sciences, must be capable of lessening the likelihood of long-duration electrical outages occurring over large service areas, limiting the scope and impact of outages when they do occur, and rapidly restoring power after an outage.

Here is an example of a resilient power system scenario: A flood forces a local utility substation to shut down, interrupting electric service. Within seconds, residential photovoltaic (PV) solar panel systems with battery storage automatically detect the loss of grid power and switch to an “islanded” mode to keep the power on. At the same time, a backup battery system at a local fire station enables the utility company to keep its communication equipment on so it can coordinate rescue operations. When the utility company is able to restore service, these backup resources will seamlessly reconnect to the grid, ready to be used during the next incident.

A completely resilient electric grid will help communities keep the power on during man-made or natural disruptions.

How Does Solar Improve Resilience?
Solar energy technologies can play an important role in strengthening our energy system’s resilience. Two key attributes make solar a unique asset for resilience. The first is that solar generation can be distributed, as opposed to centralized. This means individual buildings can host their own solar systems to meet some or all of their power needs. Communities can combine solar with storage and other technologies to create a microgrid that will provide power to critical infrastructure when it is needed.

Most electric power is generated in large, centralized power plants—which then send the electricity to homes and businesses through power lines. This power can be disrupted if the transmission or distribution system gets damaged. Distributed generation in combination with local energy storage allows power to be generated locally, near the customers, and could be used even if the centralized system experiences interference or disruption.

The second attribute that makes solar energy a key contributor to resilience is that sunlight-generated electricity can be stored and discharged without the need for fuel deliveries, unlike conventional diesel generators, which are the most common source of emergency backup power. In a long outage, solar and its associated energy storage can continue delivering power, even at night, to homes and businesses.

How Does Resilience Fit into the Solar Energy Landscape?
Adoption of distributed energy resources, such as rooftop solar generation, is increasing. There are over 2 million solar generators on the U.S. distribution system, representing about 40% of total PV capacity, with steady growth expected into the future. In addition to providing energy savings, solar energy systems have the potential to make homes, commercial buildings, and entire communities more resilient. By identifying the critical infrastructure in a community—like hospitals, fire stations, and shelters—and equipping those buildings with solar and energy storage systems, the community can respond better to, and recover faster from, electrical service loss.

Resilient systems like these have been built and demonstrated in regions prone to outages, fuel-supply constraints, and natural disasters. For example, the DOE’s SunSmart program helped equip more than 100 schools with backup solar and storage systems. In response to power system vulnerabilities revealed by Superstorm Sandy, the New York Governor’s Office of Storm Recovery announced a project in 2019 to place solar panels and energy storage systems in flood-prone areas.

The DOE has also launched major initiatives to address the increasing resilience challenges, including:

A partnership with the National Laboratories to provide technical support to Puerto Rico after Hurricane Maria in 2017
The North American Energy Resilience Model
The Grid Modernization Laboratory Consortium (GMLC)’s Resilient Distribution Systems research programs
The Solar Energy Technologies Office’s Advanced Systems Integration for Solar Technologies (ASSIST): Situational Awareness and Resilient Solutions for Critical Infrastructure funding program
Technically, residential solar panels alone are not enough to make your home resilient. This is because solar systems generally depend on the electrical grid to produce power—and, for safety reasons, they’re designed to switch off if the grid power cuts out. For solar panels to produce power on their own, they need two things: a properly configured inverter and a storage system. The solar inverter generates alternating-current power from the solar panel’s direct-current output, while the storage system, like a battery, can keep power steady amid changes in output and building loads.

Communities can become more resilient with advanced solar technologies. Pairing solar with storage can help make solar energy available during outages. With new grid-forming inverters, a solar-plus-storage system may be able restart the grid after disruptions if the system is large enough. Microgrids could also provide resiliency benefits. Microgrids are a smaller version of the electrical grid that can help a large building, campus, or neighborhood balance its electrical supply and demand when the larger grid is down. By combining solar with these new technologies, we can build a robust energy system that responds to whatever threats and disruptions might lie ahead.

How Can I Help Build Community Resilience?
Community officials can use the Federal Emergency Management Agency (FEMA)’s electric power mitigation guide to work with public and private actors to mitigate hazards while planning and developing projects. FEMA also provides guides to expanding mitigation to build preparedness in disproportionately at-risk communities and in transportation and other sectors.
This GMLC metrics report defines how resilience should be assessed when making decisions about grid modernization.
The National Renewable Energy Laboratory promotes resilience in remote communities, as well as at the building, community, regional, and national levels. The lab has published the Power Sector Resilience Planning Guidebook: A Self-Guided Reference for Practitioners.
At the regional level, the Resilience Roadmap: A Collaborative Approach to Multi-Jurisdictional Planning provides holistic planning guidance for local, state, and federal entities.
Organizations can use the Technical Resilience Navigator to identify their resilience gaps and prioritize solutions that reduce risk from disruptions to energy and water services.
Visit Solar Market Pathways for resources, tools, and real-world examples that help local governments, community advocates, solar project developers, emergency management professionals, facilities managers, and others understand all the aspects of implementing resilient solar.