Clearly, states are beginning to focus on providing clean energy power solutions in the face of ever increasing severity of storms and the need to have resilient power available for disaster response.

How Solar+Storage Could Protect Multifamily Affordable Housing from Power Outages

Lewis Milford | Clean Energy Group


About Lewis Milford

Lewis Milford is president and founder of Clean Energy Group (CEG) and founder of the Clean Energy States Alliance, two national nonprofit organizations that work with state, federal, and international organizations to promote clean energy technology, policy, finance, and innovation. For Clean Energy Group, Mr. Milford directs the Clean Energy Finance Project ( and the Resilient Power Project ( as well as other projects involving offshore wind and renewable power.

Mr. Milford is also a nonresident senior fellow at the Brookings Institution. He works with many public agencies and private investors in the United States and Europe that finance clean energy.

Mr. Milford is frequently asked to appear as an expert panelist at energy conferences throughout the United States and Europe. His articles on clean energy have appeared in many publications including The New York Times, The Boston Globe,The National Journal, The Huffington Post, and Solar Today.



Why did Clean Energy Group decide to focus on solar+storage, and why now?

Since 1998, Clean Energy Group (CEG), a national nonprofit organization, has worked to expand markets for clean energy technologies, including solar, land-based wind, offshore wind, fuel cells, energy storage, and biomass. As part of our work, Clean Energy Group has advocated for the use of advanced clean energy technologies in critical public and private facilities that need reliable power during power outages. Instead of depending on dirty and unreliable diesel generations, Clean Energy Group has advocated for the use of clean, community-driven distributed energy sources like solar PV with battery storage to provide energy security and back-up power in the event of power emergencies.

This report, Resilience for Free: How Solar+Storage Could Protect Multifamily Affordable Housing from Power Outages at Little or No Net Cost, is part of Clean Energy Group’s work with the Resilient Power Project, which began in 2013 after Superstorm Sandy left over 8 million people without electricity. The impacts were severe, especially harming vulnerable populations like the poor, the elderly, the disabled, and those needing supportive services. With support from several national foundations, the Resilient Power Project has worked to advance state and municipal efforts to address the need for resilient power systems in the Northeast and beyond.

Through the Resilient Power Project, Clean Energy Group works to help communities install these systems in critical facilities such as police and fire stations, schools that serve as community shelters, affordable multifamily housing, food banks, wastewater treatment facilities, and other locations that need power to keep communities safe when the grid goes down. The project is especially interested in ensuring that these new protective power technologies are deployed in low-income communities, which are particularly vulnerable to grid outages, and which are often overlooked when new, innovative technologies are adopted. The project will help communities to better prepare for, and more quickly recover from, damages caused by power outages during destructive weather events, with installations of cleaner distributed energy sources.


Can you describe a typical solar+storage project for us including the process, technology and major players involved?

Solar+storage involves pairing PV panels with battery storage systems to create grid-connected, distributed, behind-the meter-resilient power solutions for energy assurance as well as clean energy. The batteries that are being used in these types of configurations are generally lithium-ion batteries, the same technology that Tesla’s Powerwall and Powerpack are using. Some projects are also using lead-acid batteries. Along with the PV panels and the batteries, another key technology involved in a solar+storage system is the battery-based inverter, which is needed to convert the flow of DC power from the PV panels to AC power that we use in our homes and buildings, and then back again in if AC current is to be used to re-charge the battery.

Importantly, so that PV panels can continue to provide electricity to a building if the grid goes down, the battery-based inverter includes an automated transfer switch that enables the system to disconnect from the grid and continue to operate critical loads during a power outage, and then once grid power is restored, it will automatically switch back to grid-interactive mode. This technology allows the solar+storage system to island from the grid and continue to provide electricity to critical loads, such as water pumps, communications, lighting, and elevators, when it is needed most.


How is solar+storage currently being used nationally, and what are the benefits of installing it in affordable housing and low-income communities?

The market for distributed solar+storage technologies is relatively new as the costs of both PV panels and batteries has declined dramatically in recent years. Beyond the benefits of clean energy, many large corporations have begun to use these systems to take advantage of the economic benefits that are obtained through reductions in electricity demand charges that utilities impose based on customer peak demand. For Clean Energy Group’s focus on low-income housing, we are working to make sure that these benefits are available to the country’s most vulnerable populations, not just to its most privileged.   

More than an inconvenience, the loss of power to those who rely on it to power elevators, mobility devices, medical equipment, and refrigeration for medicine can be life threatening. When disaster strikes, it is often low-income and those requiring supportive services that have the most difficulty dealing with the consequences. They often lack the income, savings, insurance, and access to communication channels and information to recover from the adverse impacts of disruptive weather events.

Hospitals, nursing homes, 911 call centers, emergency shelters, and other critical facilities also need reliable, resilient electrical power to deliver emergency services to the community when the supporting power grid is down. These most vulnerable residents and those who depend on critical public facilities don’t have time to wait for improved technologies to trickle down to their communities—not when they can be economically feasible today. Solar+storage systems are available now to help them prepare for future storms and power outages.

These technologies can provide reliable power for a range of critical facilities and essential building service loads. They can power water booster pumps, lighting, telecommunications, fire alarms and security cameras, elevators, and climate controls. They can mean the difference between safety and harm, protection and tragedy, dangerous evacuation or sheltering in place when outages occur. In addition to protecting people from harm during prolonged power outages, solar+storage also can enable low-income housing developers to generate significant electric bill savings by reducing utility demand charges or generate revenue through providing grid services such as frequency regulation.


This analysis uses representative affordable housing properties in New York, Chicago, and DC. Why did you choose those cities, and can the findings be applied to other areas nationwide?

These cities were selected based on the economic opportunities available in each location and the availability of data on building profiles, which allowed up to develop sound models. In short, these are cities where affordable housing developers have an interest and resiliency and where economic opportunities exist for solar+storage systems. These three markets differ significantly from each other, as do markets nationwide, and many of findings can be applied to other areas.

The buildings modeled in our analysis are representative of multifamily affordable and senior housing facilities with multiple floors and resident capacities in the range of 100 to 300 units. In the Resilience for Free report, we enlisted the help of experienced solar+storage experts to help prepare the economic models and the technology options. Our analysis found favorable conditions for resilient solar+storage project development in each of the three cities analyzed, as well as the need for additional targeted support of these projects to encourage larger market opportunities. With the favorable economics demonstrated in these three cities, we believe that these systems can be economic in other areas of the country with high demand charges and properly structured electricity markets can help make these systems more economically viable. Our analysis further suggests that policy makers who want to advance resilient power solutions available to low-income communities in their states need to make it a priority with sufficient incentives and supportive regulations.


Are there some parts of the country where the climate or other considerations make it impractical for solar+storage projects?

The ability to power critical electric loads during a power outage with clean energy technologies to keep people safe should be considered as practical in all parts of the country. Power outages happen all the time for all kinds of reasons: storms, downed power lines, human error, grid failure, fires, earthquakes, excessive power demand, short circuits, and animals. Millions of people across U.S. are affected each year by power outages. While diesel generators have traditionally been seen as the safeguard for these power failures, they have proven to be unreliable as they sit idle most of the time and rely on outside fuel deliveries to be used over a long duration event; they are noisy, dirty, and they represent sunk costs. Solar+storage can provide clean electricity 24/7 and also provide resilient power when the grid goes down. If market conditions are right, they can provide resilient power at little or no cost over the lifetime of the system.


If the economics for solar+storage in affordable housing properties are favorable, how do we get developers to actually install them?

The Resilience for Free report, and Clean Energy Group’s previous reports on resilient power, should help build the technological, financial, moral, and economic case for the use of solar+storage technologies for low-income communities. Thought the first projects are always the hardest to get built, we are convinced that developers will begin adopting at this technology solution as an economic benefit and a way to keep the residents of the buildings they build safe in a power emergency. Once the first projects are built, others should follow. Our Resilient Power Project offers small technical assistance grants to help cover the initial scoping and feasibility predevelopment costs of implementing resilient solar+storage in affordable housing and other facilities critical to vulnerable communities.


What changes do you expect to see in the clean energy market, and in solar+storage technologies specifically, over the next decade?

Since this project began two years ago, more than $500,000,000 in public dollars from programs in Northeast states has gone to support these new resilient power systems. Because of these programs, 40 municipalities in the Northeast now have over 90 resilient power projects underway, at a likely capital cost of several hundred million dollars. Larger resiliency goals have now been translated into real, on-the-ground projects that are:

  • Protecting communities and their vulnerable populations

  • Providing more reliable power protection

  • Reducing reliance on fossil fuels

  • Creating healthier communities and reducing utility bills with new clean energy + storage technologies.


Clearly, states are beginning to focus on providing clean energy power solutions in the face of ever increasing severity of storms and the need to have resilient power available for disaster response. As more cities are hit with long-duration outages from severe weather events, the ability of residents of multifamily apartment building to access electricity in a blackout in order to “shelter-in-place” safely, with critical power loads covered is essential. States will lead the effort to bring these benefits to low-income communities as a matter of social equity.

The costs of PV and battery storage technologies should continue to decline over the next decade, allowing more uptake of the technology. Battery storage is an enabler of more solar and wind power, which provide variable output of electricity. Batteries can store excess power when it is generated, and provide it when needed. They can do so without emissions, they can release and absorb power quickly to help with grid stability, and they can keep the lights on when the grid goes down. It is a winning technology combination.

What is needed to move this market along is coordinated activity from a variety of players to provide financing for these projects to be built. There are numerous market participants who have roles to play in a financing strategy for solar+storage projects:

  • Many solar+storage companies bring their own third-party financing to projects they develop.

  • Commercial and state “green” banks can provide debt financing to early stage technology markets once there is demonstrated demand for financing and credit enhancement to reduce risk.

  • State and municipal agencies can provide incentives, subsidies, and credit enhancement to reduce project and credit risk.

  • Foundations can provide technical assistance funding for project predevelopment expenses, program related investments (PRIs) for credit enhancement, and grants that support new financing programs for resilient power projects.


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