• Facilitated a stakeholder process to investigate and plan for rapid growth in solar from <2% of electricity sales in 2014 to 20% by 2025.
  • Created the Vermont Solar Pathways report which examines challenges to an advanced solar future and how they can be overcome.


Solar PV is the fastest-growing form of energy in Vermont. From 2012 to 2017, Vermont’s solar energy capacity increased almost nine times to 227 MW, a compound annual growth rate of 54%. During this time, the portion of electricity from solar grew from 0.5% to 5%. The state is one of the national leaders in net metering, community solar, and solar jobs per capita.

In 2011, the Vermont Comprehensive Energy Plan set a goal to have renewable energy supply 90% of the state’s total energy needs (including electricity, heating and cooling, and transportation) by 2050. The Department of Public Service completed a Total Energy Study to examine the feasibility and cost-effectiveness of various paths to the 90% goal and related emissions goals. The General Assembly created a Renewable Portfolio Standard (RPS) that includes credit for projects—such as electric vehicles and modern wood heating—that switch end uses away from fossil fuel, making the RPS essentially a total energy portfolio standard. Achieving the state’s energy goals will require major contributions from distributed resources and the development of supporting infrastructure such as energy storage, electric vehicle charging stations, and upgraded distribution systems.

The Vermont Solar Pathways project used scenario modeling and stakeholder engagement to create a broadly supported plan to get 20% of the state’s electricity from solar by 2025. Scenario modeling provided numbers and graphs for examining issues, costs, and benefits, and spurred discussions at the 11 stakeholder meetings held over the course of the project. Stakeholders provided feedback to improve the model and made suggestions for variations on the scenarios.

Stakeholder Engagement

Through a process lasting more than two years, the Vermont Energy Investment Corporation (VEIC) engaged key Vermont energy stakeholders—including a range of solar energy market actors, citizen and consumer advocates, legislators, utilities, regulators, the statewide energy efficiency utility, and academic researchers—in the development of a solar master plan to address challenges and opportunities created by high levels of solar generation. The VEIC team held a series of stakeholder meetings, initially organized around strategic focus areas related to growing solar:

  • Net metering
  • Electric vehicles
  • Heat pumps
  • Smart grid
  • Energy storage
  • Incentives
  • Social equity

Though the stakeholder groups initially met separately, the varied interests of most of the stakeholders, and the overlapping nature of many of the focus areas, made combined stakeholder meetings the best option for in-depth discussions that brought together diverse viewpoints for the benefit of the project. Later meetings focused on topics such as issues relating to grid integration and balancing, economic drivers and consequences, and the dissemination of results to a wider audience.

When this project was proposed in 2014, solar was growing in Vermont, but not as quickly as in Hawai’i, California, New Jersey, or Massachusetts. Only the first two grey dots in the graph below had been measured.

Share of electricity used in Vermont supplied by solar

At these early stages, solar levels were far from reaching the goal of 20% by 2025, garnering minimal attention for solar as an area of focus. However, over the course of the project, the installations accelerated, giving new importance and urgency to stakeholder discussions about solar. The percent increase in energy from solar over the next three years could be charted on an exponential curve that, if extrapolated, could actually land solar energy production above 20% of total electricity use in Vermont in 2025. Meanwhile, utilities were struggling to keep up with interconnection requests, making it difficult for them to plan for the 2025 solar goal. The VEIC project became a resource for this planning, directly responding to utility questions and feedback with clear answers, alternative scenarios, and different data formats. By increasing buy-in from utilities, the project was able to shift how stakeholders discussed solar and a high-solar future even before the publication of the final project report.

Scenario Modeling

To determine the physical and financial investment in solar PV, grid upgrades, efficiency, and flexible load needed to progress Vermont toward its 2050 goal, VEIC created energy and economic models with different levels of assumed renewable energy generation. This scenario modeling allowed VEIC to easily create and compare related scenarios to each other and to a business-as-usual scenario. The project team started with a model that accurately reflected Vermont’s total energy system at the start of the study, and, using LEAP software from the Stockholm Environment Institute, VEIC created the following scenarios:

  • Business-as-usual: Uses existing efficiency efforts that are among the best in the nation.
  • 90×2050VEIC: Meets the 90% goal through any means of renewable energy use, based on the state’s Total Energy Study.
  • Advanced solar: Similar to 90×2050VEIC, but with about three times more solar by 2025 to meet the 20% goal. This was the main study scenario. Stakeholders suggested further variations, including:
    • Lower net metering: A version of the advanced solar scenario with more utility solar, similar to the mix seen in other states with mature solar markets.
    • Delayed deployment: A version of the advanced solar scenario that installs the solar more slowly so it costs less, but also reduces the amount of Federal Investment Tax Credit that would flow into the state.

One of the study’s key findings was that the total spending for energy and related infrastructure between now and 2025 would be essentially the same for all of these scenarios. The graph below shows the net present value of that spending, along with the percent of total energy from renewables. However, a separate analysis (not shown) indicates that the business-as-usual scenario will cost $8 billion more than any of the high-renewable-energy scenarios when total spending through 2050 is considered.

Vermont Solar Development Plan

Released by VEIC in 2017, the Vermont Solar Pathways summary report considers challenges and barriers to solar deployment and how they can be overcome. The report considers solar growth as a part of total energy rather than in isolation, which means it includes related technologies—such as heat pumps and electric vehicles—and the effects of those fuel switches. It also explores how solar will change the dispatch of electricity generation. Key report highlights include:

  • Vermont has enough land and sunlight to meet 20% of its electricity needs with solar by 2025.
  • To meet this target, Vermont needs 1 GW of solar capacity, which happens to be the same as the state’s peak electric demand. This requires more planning, investment, and upgrades to grid hardware and operations systems.
  • Investing in efficiency and solar can yield economic benefits for Vermonters and costs less than relying on imported fossil fuel, helping low- and moderate-income residents afford energy.
  • Solar is growing symbiotically with heat pumps and electric vehicles. The markets for these technologies overlap and offer utilities, installers, and contractors opportunities to innovate new business models.


Vermont Solar Pathways Vermont Solar Pathways
Author:  VEIC

This report specifies the policy, regulatory and market conditions needed for distributed solar to play an important role in meeting Vermont’s 90% renewables by 2050 energy goals.

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VEIC: Vermont Solar Pathways Project ... VEIC: Vermont Solar Pathways Project Presentation
Author:  ISC

This webinar focuses on key successes and lessons learned from the VEIC Solar Market Pathways project including, modeling, scenario planning, stakeholder engagement, and more.

Major Takeaways

The most important conclusion of the Vermont Solar Pathways study is that solar can provide 20% of Vermont’s electricity by 2025, and can do so with investments that are less than 1% of total annual energy expenditures. Over the longer term, through 2050, the study suggests net economic benefits are several billion dollars higher under the advanced solar scenario than business as usual.

In mapping pathways to reaching solar goals, the combination of stakeholder engagement and scenario modeling was more effective than either could have been alone. The long process of mapping and creating the report meant stakeholders were able to see, vet, and improve the initial models and assumptions. By the time the report was published, industry and advocates were already aware of and understood its findings because they had played a role in its creation. This level of contribution not only strengthened the content of the study, it increased its effectiveness by securing stakeholder buy-in.

Scenario modeling offers an alternative to traditional energy efficiency or renewable energy potential studies. Instead of a linear process of screening measures based on whether they reduce costs, scenario modeling answers public policy questions, like the one posed by the VEIC team about how much would it cost to have 20% of electricity from solar by 2025 and 90% of total energy from renewables by 2050. In Vermont’s case, the answer turned out to be that it would cost much less than business as usual, even though some of the investments in the first 10 years would not screen in a cost-effectiveness test. Those investments are necessary to build momentum for the level of growth needed.

Ultimately, the Vermont Solar Pathways project established a valuable process and methodologies that could be replicated—with or without modification—by stakeholders in other states.