While Superstorm Sandy made energy resilience a priority, the devastating outage on Puerto Rico has taken it to a whole new level.

Puerto Rico is only now approaching full power seven months after Hurricane Maria decimated the island, knocking out about two-thirds of transmission and distribution systems. And earlier this month, an accident knocked out power to nearly all the island's residents once again.

Sandy and Maria have spurred communities across the country to look more closely at how they treat electricity in their emergency management preparations. Many are looking at new approaches, using solar and battery storage technologies to provide greater reliability and better economics than diesel generators.

Combining solar and storage into “resilient solar” offers a number of benefits over solar alone or traditional diesel backup power systems. They can island themselves, providing power during extended grid outages. They avoid the risk of running out of fuel for gas or diesel generators. And they provide services every day — generating electricity when the sun shines and using the battery to cut peak demand charges. It’s an emergency backup system that helps pay for itself.

The concept of resilient solar is attractive, but deployment can be challenging for first-of-a-kind projects. As part of the Solar Market Pathways project from the U.S. Department of Energy, San Francisco and New York have completed in-depth feasibility studies on how to power critical facilities like police and fire stations, hospitals and shelters. The projects have generated practical tools, educational materials and software to help others follow suit.

San Francisco

San Francisco’s Department of the Environment (SFE) studied the use of solar and storage systems at facilities throughout the city that would serve critical loads in times of emergencies. 

“Neighborhood resources like fire stations, community centers and schools often become a place of operation for emergency response,” said Peter Gallotta, SFE spokesperson. “It’s critical to have backup power at these sites in the event of the next large-scale grid outage.” 

Because batteries are expensive and take up space in a facility, they are rarely sized to power an entire building. Rather, for each facility, the team in San Francisco identified the critical loads — the lights, appliances, phone charging stations, and other absolutely necessary items that would require power in the case of an outage.

The project, called Solar + Storage for Resiliency, is intended to serve as a national model, so that other cities and counties can more easily integrate solar and energy storage into their emergency response plans. SFE developed a road map and a best practices guide, with lessons geared toward other municipalities interested in energy resilience. 

The project also includes SolarResilient, a web-based tool that estimates both the solar and battery energy storage system size and physical space that would be needed to meet the critical load of a facility. The tool is designed for building owners, energy professionals, and city departments to develop equipment sizing and get an idea of the physical space necessary before embarking on more detailed studies. 

“For many resource-strapped cities, it can be an expensive and time-consuming process of reviews, approvals and RFIs just to get an idea whether such systems are suitable. The tool eliminates that step,” said Jessica Tse, distributed energy resource coordinator for SFE.   

The tool is free, does not require solar expertise, and can be used for any building or facility type anywhere in the country.

While San Francisco has backup generators at some critical facilities, Tse points out some major drawbacks with diesel and gas. “Diesel generators don’t provide any benefits during normal operation, they can be noisy and polluting, and of course they don’t work without fuel, and fuel supplies are often interrupted during a disaster,” she said “Plus, they are so seldom used that they often don’t get maintained, and then they don’t start up when needed.”

“On the contrary, on-site solar paired with batteries can provide power over an extended period in the event of an emergency, but also help meet daily power needs,” added Gallotta.

Many buildings in San Francisco have solar, but practically none are able to island during grid outages. By studying how to integrate both solar and storage as a package, San Francisco can build on progress to provide greater energy resilience. 

City University of ​New York

New York City is also advancing rapidly with solar, with over 100 megawatts deployed in the five boroughs and more under development. Both the city and state have aggressive clean energy and climate reduction goals, and are seeing rapid growth of solar. 

But like San Francisco, most of that solar is not equipped with smart inverters and storage capacity, leaving the city unable to harness this power during emergencies and blackouts. When Superstorm Sandy hit five years ago, the 672 solar arrays in New York City at that time were unable to provide power during the outage, according to Sustainable CUNY’s NYC Solar Ombudsman. 

CUNY’s own facilities were used as emergency shelters for almost a third of the city’s 9,000 evacuees. But like other facilities in the city, they faced fuel shortages that affected vehicles, backup generators and buildings.

“Solar could have been used to help power critical loads across the five boroughs on the sunny days during the blackout — and storage could have helped around the clock,” said Tria Case, university director of sustainability and energy conservation for CUNY. 

Now with more than 12,000 solar installations and growing, attention is shifting to storage. “We are working on a streamlined path for storage as well, so New Yorkers have more resilient energy options,” said Case.

Hurricane Sandy showed the importance of integrating distributed generation and storage into emergency and resiliency planning, spurring Sustainable CUNY to convene a Smart DG Hub for local, regional and federal agencies and stakeholders.

The collaborative worked to streamline costs and create scalable, replicable models for communities across the country. CUNY created a set of reports and fact sheets for installers, utilities, policymakers and consumers about resilient hardware and design and the economics of solar-plus-storage systems. 

In 2017, Sustainable CUNY released the New York City Resilient Solar Roadmap — a five- to seven-year strategic plan addressing issues around hardware, software, economics and policy. In NYC, the most significant barrier to solar-plus projects has been permitting. Because batteries are a new technology, it was unclear which agencies needed to issue permits and what the permit requirements would be. 

To help clarify the process, CUNY produced a permitting and interconnection guide for storage systems. 

“We see the guide as a vital first step; however, our work is ongoing,” said Case. “Permitting agencies, fire departments and the industry needed a framework to be able to understand this continually evolving technology field, and that’s why CUNY, as an objective and trusted third party, leads these efforts.” 

CUNY is working with local officials to implement streamlined permitting under a grant from the state office of energy research, NYSERDA.

The university is also expanding an online software tool, the NY Solar Map and Portal, to show current solar-plus-storage installations in the city and identify ideal locations for new systems to maximize the resilience benefits. An additional online calculator will analyze critical loads for residential consumers and provide a “first-floor” estimate of project size and cost.

In both New York and San Francisco, creating detailed strategies has led to a clearer roadmap on the opportunities, costs and benefits, and policy and program changes that will lead to deployment.

“We found out, yes, solar plus energy storage at these facilities is feasible,” said Jessie Denver of the San Francisco Department of Environment. “So now we need to figure how we can actually pay for the projects and get them built.”


This piece was written by Bentham Paulos, on behalf of the Institute for Sustainable Communities (ISC). ISC is the national coordinator of the DOE Solar Market Pathways program which brings together 14 diverse teams from across the country under a single goal: to increase solar energy adoption by reducing the soft costs associated with solar.

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