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The Metric

Aug 31, 2015

Scoring Residential Solar in Connecticut

How a municipal solar scorecard can identify potential gains for Connecticut municipalities
Map of CT Municipal Residential Solar PV Per Capita Generation 2013-2015 (created by Danny Macri using CartoDB)

In 2012 Connecticut’s legislature set a statewide goal: with incentive support provided by the CT Green Bank’s Residential Solar Investment Program (RSIP) install enough residential solar PV panels by 2022 to generate 30 megawatts (MW) of power annually. The CT Green Bank, whose task is to leverage public and private funds to accelerate the growth of green energy in Connecticut, met this solar PV target in 2014, eight years ahead of schedule. A new bill signed into law on July 2, 2015 by Governor Malloy expanded the program target from 30 MW to 300 MW. Between March 2012 and August 28, 2015, the CT Green Bank has completed enough residential solar projects in the Nutmeg state to power almost 7,100 CT homes [1]. These projects have the capacity to support 55 MW [2] of power, which generate an estimated 61,000 megawatt hours (MWH) [3] of electricity each year [4].

Connecticut’s Renewable Portfolio Standard (RPS) has set an ambitious goal of generating at least 20% of the state’s electricity with Class I (renewable) sources by 2020.  With close to 100% of Connecticut’s energy mix coming from nuclear and natural gas, state legislators, utilities, and electricity consumers are looking for alternative ways to diversify CT’s portfolio.  Powering the state with a varied mix of sources would enhance distribution reliability, hedge against fossil fuel price volatility, create jobs, and improve air quality. Solar energy and fuel cells, RPS notes, have the highest growth potential of all alternative fuel sources in the state.

Increasing solar PV adoption will also help Connecticut meet the new federal Clean Power Plan's targets [5]. With political and economic incentives aligned like never before, Connecticut lawmakers and office-holders have tasked the CT Green Bank to focus on expanding solar PV on rooftops throughout the state.

The Green Bank’s support has resulted in a solar PV boom. Connecticut has witnessed a doubling of PV panels approved and installed between December 2013 and 2014. Can the state sustain this breakneck pace? The gap between the number of approved and completed projects is widening. See the graph below. During the last two years, for every new MW of solar energy installed, on average, an additional 1.7 MW were approved. Why are we unable to keep pace with demand?  Since solar PV permitting is managed locally, what can municipal officials, businesses, and citizens do to ensure solar PV installations are completed in a timely manner as more and more projects come down the pipeline?


Data sourced from: CT Green Bank August 28, 2015 Residential Solar Investment Program data.

Yale’s Environmental Performance Index (EPI) partnered with the CT Green Bank to help answer this question. Over the next 10 months, EPI will develop a scorecard for each of Connecticut’s 169 municipalities assessing their support for residential PV panel installation. The global EPI gives policymakers from 178 countries a view of their nation’s environmental performance, highlighting areas where they are doing well and where they are falling behind. Applying the same methodology to municipalities, and specifically to residential solar policy, we will provide municipalities an objective analysis on what they can do to help the state meet its renewable energy goals, while creating jobs and improving quality of life for residents.

While the state sets high-level targets, provides incentives, and creates financing mechanisms, municipal governments inspect projects, issue permits and conduct or participate in initiatives and programs that incentivize adoption of solar PV. Cities and towns can use the scorecards as tools to track their policies’ effectiveness in encouraging residents to adopt solar power for single-family homes and gauge public support for municipal programs and regulations. The scorecards will help municipalities more effectively serve their constituents, lower PV installation costs, and will drive business for installers.

PV capacity in Connecticut has significantly increased over the last few years and, as Map One below shows, there is potential for even larger gains ahead. The map visualizes per capita solar electricity generated by Connecticut towns and cities. Toggling the map’s layer widget reveals sizeable per capita increases in the solar electricity generated from 2013 to 2015. The boost in solar energy production is not, however, spread evenly across the state. While some municipalities, such as East Haddam and Hampton, have increased their kilowatt hour (kWh) per capita rate by more than 50, others have not.  On average, residential customers consume 8,600 kWhs per year [6].

Map One’s checkered distribution of estimated generation rates per capita suggest that PV adoption varies according to location and perhaps other factors. Granted, some variables may be out of a municipality’s control. For example, the predominance of multi-family residential complexes or large student populations in certain areas would result in lower PV rates given limited rooftops and yard area per resident and large transient populations. The map does convey that municipal support of PV installations is related to higher adoption rates. About a third of CT municipalities have participated in Solarize campaigns, which have the town partner with an installer to drive PV panel installation. The towns with the highest per capita electricity generations tend to be the ones that have used the Solarize model. The scorecards we develop will help towns with lower generation rates per capita learn what’s working in towns with higher generation rates.

Map 1: CT Municipal Residential Solar PV Per Capita Generation 2013-2015*


Link to full map: http://cdb.io/1F4gkly

*This map only reflects estimated solar PV per capita generation rates from solar PV panels that were installed through the CT Green Bank Residential Solar Investment Program from March 1, 2012 to August 28, 2015. It neither includes power generated from outside of the program nor from commercial entities.

This second map shows that the time lag has increased from the day a resident applies for Green Bank incentives to the day the project is completed. Statewide, the timeline has lengthened from 127 days to 161 days between 2012 and 2015. The reasons for the increase vary from project to project. Installers may not have the staff to meet existing demand, incentive approval and financing may be delayed, or municipalities may take longer to approve permits. How can municipalities provide a responsible level of oversight while decreasing the amount of time it takes for a project to be completed? EPI will bring together installers and municipal officials to suggest metrics to fairly and accurately assess municipal support. The scorecards will then assess how close municipalities are to achieving those metrics.

Map 2: CT Residential Solar PV Installation Timeline and Scale-Up**


Link to full map: http://cdb.io/1F4ewcm

**As with the map above, this map only reflects solar PV data from the CT Green Bank Residential Solar Investment Program from March 1, 2012 to August 28, 2015.

Of the 55 MW of finished residential solar projects, the CT Green Bank has approved but has not yet completed projects that can generate an additional 39 MW, amounting to 42% of total approved capacity [7]. The installed versus approved capacity for each town can be found in Map 2 above. Some towns are expected to increase capacity five-fold. But this additional and future potential capacity may never be realized. Unless extended, the 30% solar federal tax credit to support new residential solar PV installations will step down to 10% for third party owned projects and 0% for homeowner owned projects on January 1, 2017. The CT Green Bank incentives will continue decrease over the coming years. Customers who have received an approved incentive must have PV project completed before the January expiration date to make use of the tax credit.

Customers and installers will have to race to install solar PV to take advantage of this financial incentive. Municipalities must increase the efficiency of permitting processes and provide additional support to residents to realize the full potential of solar power over the next year and a half. The scorecards we develop will provide clear metrics on where municipalities are performing well and where they are lagging behind so they know where they can most improve.

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Over the next 10 months, we will collaborate with local policymakers, administrators, and installers to develop scorecards that can help municipalities optimize their processes and programs and lower the cost of solar. We would like to receive input from and share the scorecards with other organizations or governing entities that may find developing a similar index useful for them. If you would like to contribute to this process or follow our progress send an email to Daniel.Macri@yale.edu.

For more information about the CT Green Bank RSIP and to access market data, visit the RSIP page on EnergizeCT. Click on the Incentives tab and scroll down to the bottom of the tab to access RSIP market data.


[1] Per home electricity consumption for CT was calculated by aggregating and then dividing the “Sales (Megawatthours)” column by the “Customers (Count)” column for CT entries from 2013 Utility Bundled Retail Sales- Residential file from the U.S. Energy Information Administration 2013 survey. The equivalent number of homes that can be served from energy produced through the CT Green Bank Residential Solar Investment Program was determined by dividing the statewide Estimated Annual Production (kWh) obtained from the CT Green Bank August 28, 2015 market report  / 1000 [to convert to MWH] by the per home electricity consumption as explained previously. For updated on the amount of residential solar PV approved and installed go here.

[2] 55 MW STC (Standard Test Condition) means that if the system operates at full performance it can generate 55 MW of power at a moment in time. Think of the capacity of a solar panel similar to the speed capacity of a car. A car may have the capacity to drive 120 miles per hour at a given moment in time. However, the car is not always travelling at 120 miles per hour during its lifespan. Though a solar panel can produce, let’s say 8 kilowatts of power, the system doesn’t always operate at maximum capacity since the sun doesn’t shine all day long and there are other variables that affect system performance.

[3] MWHs measures the amount of electricity generated per period of time. Your electricity bill is priced in kilowatt-hours (kWh) or per month. One thousand kWhs equals one MWH. The Estimated Annual Production (MWHs) per project was obtained by multiplying the MW capacity by a capacity factor of approximately 0.13 (depending on the anticipated efficiency), and 8760 hours per year. The statewide estimated annual residential solar PV production aggregated all projects. The capacity factor will depend on hardware and location specific parameters thus the generation data presented here is solely an estimate.

[4] The CT Green Bank through the Residential Solar Investment Program and its predecessor, the Connecticut Clean Energy Fund have approved a total of 107 MW of residential solar power.

[5] The federal Clean Power Plan requires CT to reduce CO2 emissions per megawatt hour of electricity by 7% and increase overall emissions by no more than 3% from the 2012 baseline.  

[6] Ibid (see footnote 1 for raw data source).

[7] Ibid (see footnotes 2 and 3).

A previous version of this article noted that federal solar tax credits will step down on December 31, 2016. It has since been revised to note that the tax credits will step down on January 1, 2017.