Vermont Affordable Housing Development Sets New Standard for Resilient, Zero-Energy Homes

Author: Maria Blais Costello, Clean Energy Group | Project: Resilient Power Project

Each McKnight Lane home is equipped with rooftop solar and battery storage. Photo by Clean Energy Group.The McKnight Lane Housing Development in Waltham, Vermont is doing what no affordable housing project has done before: It is offering rural, low-income tenants zero-energy, single-family housing that also includes resilient solar energy storage systems.

Solar PV paired with battery storage (solar+storage) is a relatively new technology application for housing, and though companies such as Tesla and Sonnen have recently made these systems available, usually wealthy households are the first adopters. Residential solar+storage systems that offer reduced pollution, back-up power, and cost-savings haven’t trickled down to families with modest means. But in Vermont, steps were taken by community leaders, affordable housing developers, NGOs, philanthropy, the state’s largest utility, an energy storage systems company, and a Vermont modular home manufacturer to show how these benefits can be accessed by low-income communities. The McKnight Lane development is unique and important because it shows that solar+storage systems are ready for deployment in affordable housing today.

Project Summary

The McKnight Lane Housing Development came together thanks to the collaboration of organizations from across Vermont, led by the project developers, Addison County Community Trust and Cathedral Square. With additional contributions to the project by community development agencies, philanthropy, industry, finance entities, government agencies, and nonprofit organizations, expertise was leveraged and more than $3.6 million was raised to cover development costs, which included site cleanup, the new infrastructure, and fourteen customized, zero energy, single-family modular homes with rooftop solar PV systems. Additional funding of $130,000 was raised to help cover the purchase of the energy storage systems for added resiliency and cost savings.

The tenants of the duplex-modular homes have access to the some of the most advanced clean energy housing available anywhere. The VERMOD modular homes were designed to be so energy efficient that with the addition of the solar panels, the electricity cost for the homes is expected to be zero over the course of a year, even though the home’s heating, cooling, ventilation systems, and all major appliances are powered by electricity. The rent for the homes is below market, and the housing will serve families below 60 percent of area median income; and the rent will include electricity.

Tenants will also receive the benefits of resilient power with the inclusion of Sonnen smart solar energy storage systems, in addition to the 6-kW solar PV panels installed on each home. The combination of solar PV and energy storage systems will enhance each home’s energy performance and provide emergency backup power during a power outage. So while other homes may be in the dark, McKnight Lane residents will have power to keep them safe.

What is Energy Storage?

Simply put, energy storage is an electric system that uses high-capacity batteries with other system components to store power generated from the solar PV panels for use when it is needed, like at night or during a power outage when the electricity grid can no longer supply the home with power.

How does it Work?

When the electricity grid is up and running, the solar+storage system functions similarly to a regular solar PV system: meeting the home’s electricity demand, sending excess electricity generated by the PV panels to the grid, and drawing electricity from the grid, if needed, to power the home.

The solar+storage system in each home is designed to be fully operational with no action needed from the tenants. The systems are monitored electronically by electric utility Green Mountain Power and battery manufacturer Sonnen, and maintained by the Addison County Community Trust. The solar+storage systems will automatically shut down if there are any critical errors. So, unlike some energy efficiency measures, tenants do not need to do anything to get the full benefits from the solar+storage system.

What Happens during a Power Outage?

Unlike solar-only installations, solar+storage systems can continue to provide backup power to the home when the grid is down.

When the energy storage system’s automatic transfer switch detects a power outage, the solar+storage system will disconnect from the grid. This is done so that electricity that might be coming from the PV panels will not enter the grid and cause harm to anyone repairing the power lines.

Once the system disconnects from the grid, it can provide emergency back-up power to the McKnight Lane tenants until grid power is restored. The electricity stored in the batteries will be used to power essential appliances, the ventilation system and the heating and cooling systems. And during longer power outages, the solar panels will recharge the batteries whenever the sun is shining. The energy storage system can provide at least six hours of back-up power to the home without recharging.

When the sensors in the automatic transfer switch detect that the grid power has been restored, the switch connects the main service panel back to the utility grid after five minutes of stable grid power. All of this will happen automatically. The batteries will be re-charged by grid power if the solar panels are not generating electricity during the night, or by the solar panels if the sun is shining, ready to provide clean, resilient power again if needed.

What are the Other Benefits of the Solar+Storage System?

In addition to providing resilient power to the McKnight Lane residents, the energy storage systems will also be used by Green Mountain Power to provide peak load reduction and demand response, grid services that will save money for the utility’s ratepayers. The McKnight Lane project will demonstrate how solar energy storage systems can improve the safety, reliability, and performance of the grid, and also deliver cost savings to its customers.

Clean Energy Group and the Clean Energy States Alliance will be working with the energy storage system supplier, Sonnen, and Green Mountain Power to collect performance data on the energy storage systems and provide system optimization analysis. Once the data is in, both organizations will work with stakeholders to replicate this project in Vermont and throughout the Northeast.

Read more about the McKnight Lane project on our Featured Installation page, and on our press page. Clean Energy Group is working on similar projects across the country through its Resilient Power Project. More information can be found at


This blog was also posted on Renewable Energy World.

The States’ Role in Providing Solar Information to Consumers

Author: Warren Leon, Clean Energy Group | Project: Clean Energy States Alliance

solar-guide-coverState governments have an increasingly important obligation and opportunity to present the public with sound, unbiased, user-friendly information on solar energy systems and financing options. With hundreds of thousands of solar photovoltaic (PV) systems being installed at homes, businesses, and institutions, consumers need help to ensure that they make decisions that give them long-lasting satisfaction rather than regrets.

The need for consumer information from states is greater for solar systems than for more traditional large purchases. The solar industry is relatively new and does not have well-established brands, easily accessible product review websites, or industry-specific consumer protection laws, such as automobile “lemon laws” and standardized disclosure forms for car leases.

Few people who have invested in solar PV have been unhappy with their purchases. But as the industry grows, it is important that consumers know that the equipment they purchase will perform as advertised, and that they don’t feel misled by unreliable vendors. Otherwise, long-term public support for solar could erode.

State government agencies are well placed to provide information that can help consumers choose wisely. A state agency can be impartial and does not have a vested interest in having a consumer make one type of solar-related choice over another. Accurate information from the state can give consumers much greater confidence in their decision to go solar.

There are a range of specific reasons why states should consider providing more information on solar:

  • Many states have policies and incentive programs to encourage solar development. States can bolster those policies and programs by offering information that facilitates good decision making by solar consumers.
  • If states do not provide information proactively, they may expend more resources responding to individual inquiries about solar technology providers and to questions about solar financing options, as well as redressing problems concerning solar purchases.
  • The advent of new solar financing options, such as leases and power purchase agreements (PPAs) in many states, helped fuel the rapid growth in the number of solar installations, but it also made consumers’ decisions more complex. Consumers can have difficulty understanding and evaluating all the provisions in the contracts they are offered. They may not know about contract provisions that would be beneficial to them or how to make sure they are included. A state energy agency or consumer protection agency can help consumers understand and evaluate the different financing options.
  • Although most solar installation companies seek to deal with prospective customers professionally and appropriately, there have been instances of overly aggressive or misleading marketing and sales tactics.
  • Solar PV equipment and installation quality can vary, especially because of the technical complexities of the systems. Better information can help customers understand the choices in terms of equipment quality and function, encourage them to obtain multiple quotes when shopping for a system, enable them to ask better questions of installers, and better prepare them for maintenance and use of their system after installation.
  • It can be difficult to quantify with precision the costs and benefits of a solar installation. It is therefore important for consumers to understand the economic assumptions made by installers who provide a cost estimate for a system. Providing guidance about questions to ask and the factors to consider, such as possible future changes to electricity rates and net metering policies, can help customers better understand the risks and financial consequences of their decisions.
  • States have an interest in maintaining a robust, competitive, and fair marketplace for all businesses, including solar businesses.

To help states decide what types of solar information to disseminate, the Clean Energy States Alliance (CESA) has just released Solar Information for Consumers: A Guide for States. This free guide describes the types of information that can be useful, highlights existing educational efforts by states, and provide models and useful resource information. Although the focus of the guide is on educational efforts that could be undertaken by states, its messages and approaches can apply to municipalities, counties, and municipal utilities.

On November 17 from 1-2 PM ET, there will be a webinar to provide an overview of the guide and answer questions (register here). Both the guide and the webinar are products of CESA’s Sustainable Solar Education Project, which is supported through an award from the U.S. Department of Energy SunShot Initiative. More information about the project can be found at More information about the SunShot Initiative can be found at


This blog post was also published in Renewable Energy World.

Energy Storage Is the Next Clean Energy Revolution

Authors: Lewis Milford and Seth Mullendore, Clean Energy Group | Project: Resilient Power Project

state-of-charge-coverThe next wave of America’s clean energy revolution is all about energy storage. Though rapid growth is anticipated, the battery storage market is still very small, with a few thousand projects around the country. Energy storage is currently where solar was a decade ago, but now there are over a million solar projects in the nation. To get to scale on storage, smart policies are needed. But so far, we have not seen a comprehensive state model to promote energy storage—that is, until now.

Earlier this year, Massachusetts took the lead with the country’s first comprehensive state plan on energy storage in a groundbreaking report called “State of Charge.”  The report calls for the creation of new, multi-million-dollar grant and rebate programs to buy down the upfront costs of both utility-scale and distributed, customer-sited storage. And, it proposes investigating new ways for the regional transmission operator to compensate energy storage resources for the grid services they can deliver.

Energy storage can save utility customers significant money off their electric bills. When electricity is stored throughout the grid, it can flatten demand by allowing homes and businesses to run on stored power during high-demand hours. This also makes solar more economically attractive by allowing customers to use stored solar energy to avoid high utility demand charges or peak electricity pricing under time-of-use rates. Storage can also make the grid more reliable by storing intermittent renewable energy for when it is needed most, which can also enable greater growth of solar projects.

State of Charge found that Massachusetts ratepayers could benefit from storage deployments above and beyond California’s groundbreaking energy storage mandate, which is by far the largest in the country. A proposed investment of around $1 billion in energy storage by 2020 would create economic benefits of over $3 billion to the state’s ratepayers and customers. Neighboring states throughout the Northeast also would benefit from lower regional electricity market prices.

The Massachusetts plan also shows how storage can help states meet their greenhouse gas reduction goals. According to the study, large scale storage deployment could avoid more than 1 million metric tons of GHG emissions over 10 years in Massachusetts, the equivalent of removing more than 200,000 cars from the road.

The public health impacts of reducing emissions through energy storage deployment could be significant. A recent study out of California found that proper siting of energy storage could improve air quality by reducing the use of fossil-fuel peaker plants when electricity demand is high. This could have dramatic health benefits in the low-income communities where many of these fossil-fuel plants are located.

State of Charge recognizes that storage won’t provide these benefits without policy support. To date, too few states support the scale up of energy storage. This leaves the industry too small to deliver all the benefits that are possible. Early markets for energy storage are fragmented, which means they do not have incentives to create revenue streams from storage, and are poorly understood by important stakeholders like state policy makers, utilities, and grid operators. The result is too few projects serving too few customers.

We can do better. Energy storage needs the same types of support that have led to the success of the solar industry, with federal tax credits, multi-state incentive policies, and targeted efforts to reduce costs and encourage market uptake.

These groundbreaking measures in Massachusetts could be the beginning of the next wave of state clean energy policies—if other states follow its lead. Now is the time to push for more state storage policies and incentives across the U.S. Smarter use of energy storage can begin to solve many of the pressing energy and environmental problems we face.

With greater state policy support, energy storage can solidify the grid, increase solar penetration, save ratepayers money, protect public health, and reduce emissions from fossil fuel plants. This important work by Massachusetts has shown other states how to obtain those benefits from storage. There is no time to waste.


This blog was also posted in Renewable Energy World.