Resilience Scanner

Solar-Battery Backup Power for Critical Facilities

Solution Overview

San Francisco is implementing emergency backup power systems at critical facilities that integrate on-site solar energy generation with battery storage to support both climate action objectives and disaster preparedness.[1][2] This approach provides fuel-free emergency power during grid outages while advancing the city's transition to 100% renewable electricity by 2030 and net-zero greenhouse gas emissions by 2040.[2][3] The initiative serves as a national model for integrating solar and energy storage into existing disaster preparedness plans.[4][7]

Technical Components

The systems utilize grid-tied rooftop solar arrays paired with battery energy storage systems (BESS) that enable "islanding" capability, allowing buildings to disconnect from the main grid during power outages and operate independently by drawing on stored solar energy.[5] The San Francisco Public Utilities Commission installed a 95-kilowatt grid-tied rooftop solar array with battery storage at the San Francisco Public Library's Catalog & Technical Services building, marking the SFPUC's first resiliency project.[5] All BESS project plans must comply with rigorous standards from UL, NFPA (including NFPA 855), and local fire and building codes, with the San Francisco Fire Department reviewing all project plans.[1] The installations are designed to provide energy for critical loads for up to five days to help the city survive major disasters such as earthquakes.[6] These systems support critical services including refrigeration for medical supplies, lighting for shelters, communications, and backup of critical information from the main library.[5][6]

Implementation Details

In 2015, the City and County of San Francisco Department of the Environment received $1,321,200 in funding from the U.S. Department of Energy's Solar Market Pathways program, with an additional awardee cost share of $288,971, for the Solar+Storage for Resiliency project.[4][7] A three-year study funded with $1.3 million from the Department of Energy and $300,000 in San Francisco city funds examined solar-plus-storage installations at community centers.[6] City officials are considering installing solar-plus-storage systems at as many as 12 community buildings.[6] Consulting group Arup, hired to study the viability of the systems, estimated the price at $40 million, which could be reduced to approximately $26 million if the city secures a private sector partner for the installations.[6] The project produced four case studies explaining how solar+storage would function at a fire station, a police station, a building used for shelter, and another critical power-need building.[4] Proposed updates to Chapter 7 of the Environment Code require implementing solar and solar storage capabilities at Critical Community Institutions to provide emergency power without gas-powered generators, applying to new construction, HVAC replacement, or electrical updates at public safety facilities, health clinics, community centers, libraries, and emergency management facilities.[3] CleanPowerSF is procuring energy storage to meet state mandates and reliability needs.[1]

Benefits and Impacts

The implementation ensures greater energy reliability and resiliency amidst a changing climate while reaffirming the SFPUC's contribution to achieving net-zero greenhouse gas emissions by 2040.[5] These new regulations help the city prepare for and recover from energy disruptions with minimal use of additional fossil fuels.[3] By generating electricity at the point of use, rooftop solar reduces the need for costly and time-consuming upgrades to the electricity grid.[2] Solar and storage can be aggregated and dispatched to support the grid during periods of high demand, reducing the need for expensive and polluting gas peaker plants.[2] The approach addresses a critical gap in current planning, as much of San Francisco's existing resiliency planning relies on diesel generators, which could face fuel supply difficulties during major disasters that disrupt supply chains.[6] The city aims to create a model that other neighborhoods in San Francisco can follow and a planning document that other cities nationwide can use to implement similar solar and storage emergency backup power systems.[8]

Climate Adaptation Relevance

Grid outages are expected to become more frequent and severe due to climate change, making solar paired with battery storage a resilient source of backup power during these disruptions.[2] The systems address the need for resilient power at critical facilities including hospitals and emergency services, with deployment aligning with the city's climate and resilience goals.[1] The initiative strengthens a network of community hubs throughout the city where residents can access information, resources, and support during disasters by providing them with backup power, emergency supplies, and training for staff and volunteers.[9]

Business Analysis

The Solar Market Pathways program provided the primary funding mechanism, with the Department of Energy contributing $1,321,200 and the city providing $288,971 in cost share for the initial project development.[4][7] The estimated $40 million implementation cost for 12 community buildings represents a potential public-private partnership opportunity, with projected cost reduction to $26 million through private sector collaboration.[6] San Francisco is actively exploring and deploying BESS to support climate action goals, enhance grid resiliency, and integrate renewable energy, with CleanPowerSF procuring energy storage to meet state mandates and reliability needs.[1] The regulatory framework includes proposed updates to Chapter 7 of the Environment Code mandating solar and solar storage capabilities at Critical Community Institutions, creating a compliance-driven market for these installations at public safety facilities, health clinics, community centers, libraries, and emergency management facilities.[3]

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