Technical Potential of Solar Study

In 2022, the Commonwealth released the Massachusetts Clean Energy and Climate Plan for 2025 and 2030 (CECP) and the Massachusetts Clean Energy and Climate Plan for 2050 (2050 CECP). These publications outline comprehensive plans to achieve statewide emissions limits and sector-specific sub-limits. The CECP estimates that approximately 27 to 34 gigawatts (GW) of solar energy would be required in 2050 to reach these limits. This is over 10 times the amount of solar currently installed in Massachusetts. Reaching this level of solar by 2050 will require the state to significantly increase its current annual rate of solar installations.

In light of these solar energy goals, DOER undertook the Technical Potential of Solar Study to quantify the potential for solar installations in preferred and least preferred locations. DOER engaged Synapse Energy Economics to facilitate stakeholder engagement and conduct a geospatial analysis to estimate the statewide solar potential.

The results of analysis can be found below:

Geospatial Analysis (StoryMap): https://TechnicalPotentialOfSolar-MA-synapse.hub.arcgis.com/.

Report: Technical Potential of Solar in Massachusetts

DOER engaged with a wide variety of stakeholders and members of the public to learn about priorities, concerns, and opinions about solar siting throughout Massachusetts. The stakeholder and public outreach process included:

• A public survey about attitudes towards solar siting open to all Massachusetts residents, which received over 3,000 responses.
• Five public meetings were held to solicit feedback from residents and other interested parties on preferences and concerns related to solar siting.
• A Technical Advisory Committee, consisting of representatives from environmental and conservation organizations, solar developers, regional planners, and other state agencies, which met throughout the project to provide feedback that shaped the methodology and criteria for identifying suitable locations for solar.

Feedback received through the stakeholder and public engagement process was used to develop the methodology for assessing most and least preferred locations for solar.

Using stakeholder feedback, Synapse conducted geospatial analysis using ArcGIS software to estimate the likely potential for solar at each individual land parcel in Massachusetts and rank each parcel for its suitability for different types of solar. Solar potential was scored for suitability across six categories:

• Agriculture
• Biodiversity
• Other ecosystem services
• Embedded Carbon Dioxide (CO₂e)
• Electric Infrastructure
• Slope and Aspect

More detail on the suitability categories and how they were applied can be found in the Report and StoryMap.

Report

The Technical Potential of Solar in Massachusetts Report provides a detailed description of the public engagement process, geospatial analysis methodology, findings, and additional qualitative policy considerations.

StoryMap

The StoryMap allows users to explore solar suitability across Massachusetts. The online platform summarizes the results of the geospatial analysis to determine the technical potential and suitability for solar construction across Massachusetts. Users of the StoryMap can fully interact with data for each individual land parcel in Massachusetts from this analysis by clicking on a parcel to learn about its solar potential and suitability scores. The StoryMap is available at the link below:

Technical Potential of Solar in Massachusetts StoryMap

This is a screening-level analysis intended as a preliminary consideration of locations that may be suitable for solar. The potentials calculated are estimates and are not intended to provide exact amounts of solar that can be built in a specific location. The purpose of this analysis is to be a source of information for policymakers, developers, communities, and other stakeholders; readers should not interpret it as instruction or recommendations about specific locations where solar should be built or what kind of solar should be built at those locations. The StoryMap should be used in conjunction with other tools, such as electric distribution company hosting capacity maps, environmental justice community maps, and financing tools in project decision-making.

I have selected a parcel that I know to be a protected area, a recreational space, wetland/surface water, or an area that is otherwise unlikely to be developed for solar or any other purpose (e.g., playing field, cemetery, forest). Why does this analysis identify solar potential for this site?

The spatial analysis methodology included a feasibility screening in which these types of land were screened out and assumed not to have any solar potential. However, it is possible that a single parcel may contain some areas that were screened out along with other areas that do have solar potential. In this case, the entire parcel on the StoryMap will be colored to indicate that the parcel contains solar potential. This estimated solar potential does not include potential on protected, recreational, or other lands that were removed during the feasibility screening. 

It is also possible that some types of land that one might expect to be off-limits for development may not be addressed in the screening categories used in this analysis. Or, it is possible that only a portion of the identified area is protected, and the developable portion of the area is in fact a separate parcel that is not protected. In addition, it is important to observe the type and quantity of solar that this analysis identifies as being buildable at a given location—many parcels that have been removed from this analysis for the purposes of estimating ground-mounted solar potential have buildings or parking lots that may be suitable for solar development. Likewise, some parcels may feature only a small quantity of solar potential that indicates only a small portion of the overall parcel as developable.

What are the study’s main findings?

Massachusetts has more than enough solar potential to support our decarbonization requirements – about 15-18 times what we likely need. Further, the best rated parcels add up to double the amount of solar called for in the 2050 Decarbonization Roadmap. Because of the amount of suitable solar potential identified, we can be aggressive with our solar policy while balancing land use priorities and protecting our natural resources.

How did the study review land use in determining suitability?

The TPSS reviewed six suitability categories: agriculture, biodiversity, ecosystem services (like Wellhead Protection Areas, areas of critical environmental concern), embedded CO2e, distance to grid infrastructure, and slope/aspect of the parcel. 

What types of solar installations are assumed?

The study reviewed the potential for rooftop, canopy, small ground-mount (less than 1 MW), and large ground-mount (greater than 1 MW). 

What does this mean for future solar policy in Massachusetts?

We have identified areas in Massachusetts that are suitable for various kinds of solar development: canopy, rooftop, and ground mounted. With this information, we can design solar policy and incentives to promote solar in these areas.

For our environmental justice communities, we can see what areas are most suitable for solar and facilitate engagement with these communities to help them achieve their clean energy goals.

This analysis can also help inform long-term planning efforts such as the Grid Modernization Advisory Council. By identifying areas with large amounts of highly suitable solar potential, we can ensure we are investing adequately in these areas of the grid to support this future capacity. 

How were the suitability categories chosen?

We conducted a multi-pronged stakeholder engagement process, relying on public comment, survey results and a Technical Advisory Committee.

• The Technical Advisory Committee contributed over the course of 8 months, consisting of representatives from environmental and conservation organizations, the solar industry, regional planners, and other state agencies.
• We collected over 3,000 responses to a public survey about attitudes towards solar development and land use.
• We had five public meetings to inform people about the project, answer questions, and learn more about attitudes, concerns, and priorities for solar siting and land use.

I looked up my address on the Story Map and it says my house has 10 kW of highly suitable ground mounted solar potential. Does this mean the state is encouraging me to install solar in my backyard?

This study and the map are not intended to instruct or provide recommendations about where or what kind of solar should be built, but rather as source of information about where it is possible to install solar and how it may impact the suitability categories that we considered. This study was not inclusive of every potential factor that goes into solar siting, and individual parcels and their owners may have countless other factors to consider whether solar is right for them.

Will the state provide incentives for solar built in areas identified as highly suitable?

The results of this study do not impact existing state incentive programs. This is one tool that DOER and others can use, in conjunction with other tools and existing initiatives, to develop solar siting policy that is balanced with land use priorities.

Are existing solar facilities included in this analysis?

This analysis includes all solar facilities that were known to have been installed as of August 2022. It includes solar facilities built under several different Massachusetts programs, including SMART, SREC, and municipal utilities. For more on this topic, please see Section 1.2 and Section 3.2 in the report.

Why do I see solar potential on parcels that are roads?

One aim of this analysis was to estimate the potential of building solar along roadways (e.g., in grassy medians or shoulders). To do this, we relied on roadway data provided by city and town tax assessments, data on impermeable surfaces (which are frequently roads, as well as parking lots and other asphalt surfaces), and datasets on major road centerlines. There is no single dataset that identifies only the “road” section of all areas designated as “roadways.” In general, our approach was to identify the parcels likely to be roads using tax assessment data, confirm these were roads using road centerline data, and use the impermeable surface data to remove only the paved part of a roadway. Then, if a parcel had less than 10 kW of technical potential for ground-mounted solar, we instead assumed the parcel had zero kW of technical potential. However, many municipalities include all roadways in that municipality within a single parcel. As a result, when looking across the shoulders and medians of all roadways in a town, the quantity of technical potential estimated here may be larger than is possible in reality.

Does this analysis account for the hosting capacity that is currently available on the distribution system.

No. This suitability analysis only evaluates the distance to electric substations, as a proxy for the for the additional cost of solar development for any one parcel. As the electric infrastructure suitability category did not account for current hosting capacity, this is likely an overestimation of the current suitable solar potential based on electric infrastructure. Hosting capacity is essential to the ability to interconnect solar generation with the grid as well as the associated cost of development and plays a key role in specific solar siting decisions. For more information on current substation hosting capacity, please refer to the hosting capacity maps available at https://www.mass.gov/info-details/utility-interconnection-in-massachusetts#hosting-capacity-maps-.

Was environmental justice evaluated as a suitability metric?

Massachusetts defines environmental justice populations as “the segments of the population that EEA has determined to be most at risk of being unaware of or unable to participate in environmental decision-making or to gain access to state environmental resources, or are especially vulnerable.”

In our analysis, we did not include a suitability criterion related to environmental justice. The relationship between solar siting and environmental justice impacts is nuanced. Solar can reduce health impacts from fossil fuel emissions if it displaces existing fossil fuel generation, however, it is not easily determined whether the production of electricity from any one solar facility will displace emissions at any one other emitting facility.

In addition, the deployment of solar can add to increased energy infrastructure in a community already overburdened by energy infrastructure. Some environmental justice communities might see benefits from solar sited in their communities (for example, with the redevelopment of brownfields or the deployment of community solar), while others might not (for example, with the conversion of existing green spaces that provide other community benefits). Because of this, we could not make a quantitative suitability metric that incorporated all the nuance associated with environmental justice.

It is important to recognize that many environmental justice communities may face barriers to effective community planning for solar. For example, environmental justice communities may face capacity challenges to engage in proactive planning for solar projects with community benefits, such as community solar projects to serve renters and low-income residents. Environmental justice communities are one of many stakeholders that are encouraged to use the interactive StoryMap to support community planning for solar. Communities that are interested in learning more about solar potential in their neighborhoods can use the StoryMap to identify the relative suitability of different parcels according to the suitability categories that are most important to them.

For more on this topic, see Section 3.6 Environmental Justice in the report.