Integrating Solar into Nantucket’s Historic Fabric

Sponsor:  Nantucket Planning & Land Use Services (PLUS) Department & Nantucket Preservation Trust (NPT)
Sponsor Liaison: Holly Backus, Mary Bergman, Lauren Sinatra
Student Team: Katharine Miller, Shawn Mills, Morgan Raposa, Benjamin Twombly
Abstract: The overall goal of this project was to develop recommendations and resources the Town of Nantucket in collaboration with the Nantucket Preservation Trust may use to encourage and assist in the permitting of solar technologies without compromising the island’s historic and architectural character. We evaluated the guidelines in Nantucket and other historic districts, surveyed public opinion, and interviewed officials, solar installers, and homeowners with solar installations. We found strong support for the increased use of solar technology as well as strong support for the maintenance of Nantucket’s historic fabric.  We recommended ways to improve the public information, outreach, and solar technology application process to achieve these competing demands, including the use of a new online map of solar installations that we designed to be easier to use and manage.

Final Report: Integrating Solar into Nantucket’s Historic Fabric

Final Presentation: Integrating Solar into Nantucket’s Historic Fabric Presentation

Solar Map Entry Sheet 12/12/2020: Solar Map Entry Sheet

Python Cross-Referencing Script: Python Cross-Referencing Script

Sample Entry Blacklist Sheet: Sample Blacklist

Executive Summary

Background Information:

Electricity is supplied to Nantucket Island by two undersea cables constructed and maintained by National Grid. The combined capability of these two cables is 74 MW. Nantucket’s electricity demands have continued to grow at a significantly faster rate than that of mainland Massachusetts, especially during tourist season, reaching a peak load of 55 MW. This increasing demand means that if either undersea cable were to fail, Nantucket could be faced with large scale power outages until back-up generation could be implemented. This precarious situation has sparked growing concerns amongst residents and the town government that a third undersea cable may need to be installed which would come at a significant cost to Nantucket electricity rate payers. Due to these concerns, the Energy Office was formed in 2011 to create programs to promote energy efficiency, conservation, and renewable energy. One of the responsibilities of the Energy Office is to help manage the increasing demand for the installation of photovoltaic (PV) solar technologies as a means to decrease dependence on electricity through the undersea cables. Because Nantucket is a designated Historic District, proposals to install solar technologies are subject to guidelines established by the Nantucket Historic District Commission (HDC).

The goal of this project was to develop recommendations and resources to encourage and assist in the solar permitting process. To achieve this goal, we identified three main objectives

  • Evaluate current guidance and best practices for the approval of solar technologies in historic districts.
  • Identify stakeholder opinions on Nantucket about the current guidelines and approval process for the installation of solar technologies and suggest improvements.
  • Update and improve the functionality of the online map of solar installations maintained by the Energy Office.

To complete these objectives, we used a variety of methods including, analysis of the Nantucket HDC and Energy Office records to identify candidates for interviews as well as developing a survey that was distributed to the Nantucket Civic League and a list of approximately 40 residents who had previous solar projects approved. In addition to interviewing Nantucket residents, we also interviewed the three main solar installers on the island, as well as a Nantucket Official and officials from other historic districts in the Commonwealth and Rhode Island. We also familiarized ourselves with the technology used in the current solar map and the record-keeping for new approved solar projects, as well as learning about newer technologies that will allow the Energy Office to maintain the solar map with greater currency and efficiency.



For the portion of the project concerning the interactive solar map, the general requirements were two-fold: First we had to recreate the current functionality of the existing Google Maps based solar map in an Arc-GIS based layer. Second, we needed to find a way to automate the process of updating said map layer. To begin, the functionality offered by the Arc-GIS Pro software seemed to be more than sufficient for the purpose of recreating the existing solar map. By working with the town’s GIS Coordinator, we developed a method for creating the solar-map layer from a table or spreadsheet of various solar installations. The original map utilized street addresses to provide location to the various entries, but there are two main reasons that this was not possible for the new layer. First, Google Maps provides a base layer containing street layouts and addresses by default, but Arc-GIS does not. Second, some portions of Nantucket do not actually have street addresses in the traditional sense, particularly the island of Tuckernuck located off the western coast of Nantucket. To circumvent these difficulties, we had to find a new method of providing location data for entries. Manual placement of the locations of various entries was not possible due to the automation portion of the requirements. Therefore, we had to utilize data available in the base layer of the Nantucket’s GIS system. More specifically, the layer containing the shapes of all the land parcels on Nantucket, as well as their location, which was provided to us by the town’s GIS Coordinator. This shape layer can be thought of as a jigsaw puzzle of the island, with each piece being an individual parcel of land, and each parcel of land containing a set of information (attributes) assigned to it.

Records from the EnerGov database were the primary source of information for new entries, with new installations being identified via cross-referencing HDC, electrical, and building permits. This was done because the presence of completed electrical and building permits is almost always an indication of an installation being built. Permit applications on EnerGov always include the parcel number of the property in question, with the parcel number being a unique identifier for all land parcels on Nantucket. The provided parcel shape layer includes this identifier, so it is possible to match solar installation entries to individual shapes in the parcel layer. By matching installation entries to parcel shapes in this way, the parcel shape layer could be used to provide location data for these entries. The shape layer was then converted to a marker layer, a process which basically just places a marker on a point inside of the corresponding shape. We tested this method with a data set containing all existing solar installations on Nantucket. This data set was created from data sheets of solar-related permits that were provided to us by one of the town’s IT specialists. We used a Python script to identify likely installations by cross-referencing the sheets of HDC Certificates of Appropriateness (COAs), electrical permits, and building permits. We then combined existing entries from the old solar map with new installations identified using the method outlined above and filtered for duplicates.


Findings and Recommendations:

Throughout our research process we completed several interviews and distributed a survey. While each method of gathering information was different, all interviewees posed their suggestions for opportunities for improvements in the current guidelines and application process. From our interviews with residents who had previously applied, we found that there was generally a lack of awareness regarding precisely what was considered acceptable in solar installations. This sentiment was largely reinforced by the survey question regarding what potential educational items may be beneficial to the process including a “guide to going solar” webpage and solar permitting checklist. In addition to a lack of awareness, residents also voiced their concern that the current HDC guidelines are not solar-friendly enough with approximately 63% of survey respondents agreeing. Our interviews with two of the three solar installers corroborated this sentiment as they also believed that current guidance was not as fair and reasonable as it could be.

However, approximately 36% of the survey respondents, as well as the Nantucket official we interviewed agreed that the current guidelines are fair and reasonable. In general, though these parties also agreed that having other educational resources would be a beneficial change and would help to increase awareness surrounding the current guidelines and application process. Based on these findings, we recommend that our project sponsors work together to create some of the following resources:

  • An online guide for homeowners considering the installation of solar technologies
  • A checklist of steps that will be followed during the application process
  • A compilation or slideshow to show the range of installations that the HDC has approved
  • Continuing updates of the solar map to display more accurately the current state of solar installations on island

These resources would allow for a more succinct and focused presentation of essential information for those looking to install solar technology.

In addition to the creation of these educational resources, we also found that many of the respondents felt that solar panels should be allowed to be visible from public ways if the property is outside of the Old Historic District or ‘Sconset Old Historic District. This figure included approximately 61% of survey respondents, of which 30% felt strongly that these types of installations should be more permissible. This leads to the recommendation that the town of Nantucket pursue a Survey & Planning Grant from the Massachusetts Historical Commission to help fund an independent third-party review of the current guidelines similar to what the Town of Salem, Massachusetts has done with their guidelines.