Net Metering

Receive credit for generating your own power.

Thinking about installing solar panels or a wind turbine on your property? You can offset your utility costs through a process called interconnection. Interconnection is when your power generation system is hooked up to our electricity grid, which allows power to be distributed both ways. When you create more than you need, we can share it with your neighbors, and when you don’t generate enough, we can ensure you have the power you need to live your life. The process of measuring this difference is called net metering.

Net metering requires the use of a new meter that provides information on your property’s consumption, production from your generation system, and the difference between those two values. A positive variance means you have generated more power than you needed; a negative variance means we supplied energy to meet your needs after you used your generation unit’s production. In both cases, you’re seeing a lower energy bill — it’s a win-win.

Reading Your Meter

When set up on interconnection with your utility, a new meter is required to be installed on your property. This allows us to track how much energy you have placed back on our system and how much energy we have supplied you. It is called a net meter because it will determine the net, or difference in, power used and generated at your property.

On a day-to-day basis, your net meter will show whether you have needed additional electricity on top of your own generation; the number will increase based on how many more kilowatt-hours you used. Or, if you have sent a surplus back to the grid, the number on the net meter will decrease. If your system matched your energy needs, the number will remain unchanged. You may also want to have a separate meter that only tracks your energy generation.

This figure is measuring the amount of energy ( kWh) passing from your home back through the meter and onto Unitil’s infrastructure. It is important to note that this figure does not directly measure the amount of electricity generated by your facility. As your facility generates energy, your home is drawing from that power before it reaches the meter. This reading is only measuring the surplus energy that leaves your home without being used.

This figure represents the net, or difference, between the first two (+W and –W) readings on your net meter. This is your net read and is represented as a credit or charge on your next energy statement. NOTE: These readings are cumulative, meaning they do not reset to zero after each billing period. To measure a specific timeframe, check the meter at the beginning and end of the timeframe you want to check. Then, subtract the readings from the end of this period from the ones observed at the starting point to get an idea of your usage.

Did you know?

You can view your net metering historical data in your MyUnitil account.

Frequently Asked Questions

State Requirements & Applicant Information

Massachusetts Customers

As a result of the high interest in solar interconnection and renewable energy, we are at a point of saturation in some portions of our service territory. On a day of optimal generation, the potential exists for the renewable generating facilities to meet the energy needs of all the homes around them and also have excess energy feed backwards into the nearest supply substation. Any additional generation in the area may lead to safety issues at the nearby substation without specific modifications.

Unitil is required to follow the tariffs which govern interconnections in Massachusetts, and the tariff states that all system modifications resulting from solar saturation have to be paid for by the interconnecting customer or customers that trigger the need of system modification. However, the cost of these modifications are often well above the initial planned costs for these installations, which in turn leads to project delays.

As a company, we recognize the cost of this particular modification is high and that the tariff as written presents real obstacles for some small interconnection projects, especially at the residential level. While we are required to follow these tariffs as currently written, we have raised the issue with the Massachusetts Department of Public Utilities (DPU), the state regulatory body which governs such matters. The DPU has agreed to open up a review of this tariff and explore alternatives. We are committed to continuing to work with the Department of Public Utilities to find a more equitable solution for all of our customers.

Map of Affected Streets by Town (PDF)

Generating facilities with a nameplate rating greater than 10 kW AC single-phase or 25 kW AC three-phase must apply for registration of a cap allocation with the MassACA. If you have not already done so, please contact the MassACA to apply for a cap allocation in the Net Metering queue. New Solar Customers who are not Cap exempt or Municipal and submit an application after September 26, 2016, at 2:00 p.m. will receive Market Net Metering Credits (60% of excess kWh is credited). Customers with questions can email generator@unitil.com or call 603-773-6480.

Statutory caps:

The Commonwealth of Massachusetts requires each electric utility to provide net metering to customers with qualifying generation systems. There is, however, a limitation on the amount of generation that is eligible to be net-metered on each electric utility’s system. This is known as the statutory “cap” on net metering capacity. Each electric utility, including Unitil, is required to limit the combined generation capacity of all non-exempt net metering facilities to 7% of the utility’s historic peak load for non-municipal (“Private”) customers and 8% of the historic peak for municipal (“Public”) customers. See current cap numbers here.

Unitil is required by law to limit the net metering capacity in accordance with these caps (see, G.L. c. 164 s. 139). Renewable energy generating facilities with a nameplate rating of less than 10 kW single-phase, or 25 kW three-phase are exempt from the net metering cap.

The final determination of eligibility for net metering is made after it is installed and at the time the generation system has had its final inspection and commissioning test and is issued the Approval to Interconnect by Unitil. As a result, net metering may not be available to some applicants who request it, even if they have the approval to install the generation facility.

In the event that the net metering cap has been fully subscribed, the interconnection of customer generation to Unitil’s electric distribution system is still allowed, but not under the Net Metering Tariff, and Net Metering Credits would not be available for any of the excess electricity generated by the customer’s facility. Please see the chart at the bottom of this page for more information regarding the status of capacity remaining in regards to the private and municipal caps. Should you have any questions please feel free to call our office at 1-603-773-6480. We look forward to working with you.

Important net metering credit information:

Under the net metering rules, customers that are net exporters of power for the month will receive a credit on their monthly bill based on the following formula:

Class 1 and 2 customers and municipal/governmental Class 3 customers whose generation is wind, solar, anaerobic digestion or agricultural will receive credit equal to the excess kilowatt-hours (kWh) by time-of-use rates, if applicable, and the product of the sum of the following charges applicable to the rate class under which the customer takes service:	Other Class 3 customers will receive credit equal to the excess kilowatt-hours (kWh) by time-of-use rates, if applicable, and the product of the sum of the following charges applicable to the rate class under which the customer takes service:
Basic service kWh charge Distribution kWh charge Transmission kWh charge Transition kWh charge	Basic service kWh charge Transmission kWh charge Transition kWh charge

New Solar Net Metering Facilities and other Solar Net Metering Facilities that are not Cap Exempt Facilities after 25 years from the date that each Solar Net Metering Facility was first authorized to interconnect shall receive Market Net Metering Credits. Class 1 customers whose generation is not solar, wind, anaerobic digestion or agricultural will continue to receive the average loss-adjusted monthly clearing price set by ISO New England.

Net metering credits may be transferred to other electric customers in Unitil's Massachusetts service territory, on a going-forward basis only, in the months in which they are earned by completing the Standards for Interconnection of Distributed Generation - Form Schedule Z (under the Steps to Interconnection section of this website) and the accompanying excel worksheet, and then submitting as part of the normal interconnection process. Net metering credits cannot be transferred to other customer accounts after they have been earned. Net metering credits cannot be cashed out nor used for non-electric service charges.

Current Numbers:

Historical Peak Load	102.39 MW (July 27, 2005)
Private Cap Exempt Customers as of October 2023	18.88 MW

Non-Municipal Customers
Net Metering Cap (Private)	7.17 MW (7% of historical peak load)
Net Metering Online as of 2023	7.00 MW
Reserved Cap Allocations	0.17 MW
Capacity Available Under Cap	0.00 MW
Completed Applications Pending	See public/private cap information

Municipal Customers & Other Government Entities
Net Metering Cap (Public)	8.19 MW (8% of historical peak load)
Net Metering Online as of 2023	8.14 MW
Reserved Cap Allocations	0.00 MW
Capacity Available Under Cap	0.05 MW
Completed Applications Pending	See public/private cap information

The Massachusetts Department of Public Utilities approved Unitil's Net Metering Tariff, effective August 1, 2019. The Green Communities Act provides for three classes of net metering customers:

Class I: Anaerobic Digestion/wind/agricultural generation, 60 kW and less
Class I Solar: 60 kW and less using sunlight
Class I Other: All other generation (non-renewable) 60 kW and less
Class II: Anaerobic Digestion/wind/agricultural generation over 60 kW to 1,000 kW
Class II Solar: Sunlight generation over 60 kW up to 1,000 kW
Class III: Anaerobic Digestion/wind/agricultural generation over 1,000 kW to 2,000 kW
Class III Solar: Sunlight generation over 1,000 kW up to 2,000 kW

On June 15, 2018, the Small Hydroelectric Net Metering Program became effective. This is a distinct, technology-specific Net Metering program wherein each Small Hydroelectric Net Metering Facility seeks to net meter while the program is open participates in a separate cap and generates a Small Hydroelectric Net Metering Credit pursuant to M.G.L. c. 164, § 139A.

In addition to the Interconnection Application, an eligible customer must complete and submit Schedule Z in order to be considered for Net Metering.

If you are seeking to allot your credits to other Unitil accounts, please download the following spreadsheet, fill it out completely and return it as a workable Excel spreadsheet. Upload your documents securely through our Documentation Upload Portal.

A customer wishing to be certified as a municipal or other governmental entity MUST be certified by the D.P.U. as such before the Company can provide net metering service or allocate credits under the public net metering cap. Please complete the government application below and submit to the D.P.U. and the Company.

MA Net Metering Government Application (PDF)

New Hampshire Customers

As defined in RSA 362-A:1, II-b per the New Hampshire Public Utilities Commission (NHPUC), an eligible customer is an electric utility customer who fulfills one or more of the following:

Owns or operates an electrical generating facility (on-site generator) powered by renewable energy that has a capacity of not more than 1,000 kilowatts
Owns and operates a heat-led combined heat and power system (on-site generator) that has a capacity of 100 kilowatts or more but less than or equal to 1,000 kilowatts, which began operating after July 1, 2010
Owns or operates a heat-led combined heat and power system (on-site generator), with a total peak generating capacity of not more than 100 kilowatts that was installed on or before July 1, 2010 AND the on-site generator:
- Is located behind a retail meter on the customer's premises
- Is interconnected and operates in parallel with the electric grid
- Is primarily used to offset the customer's own electricity requirements

For Standard Net Energy Metering (customer-generators who received a capacity allocation prior to September 1, 2017):

If the electricity received by the customer-generator from the distribution system exceeds the electricity exported to the distribution system by the customer-generator during the billing period, the customer-generator shall be billed based on the net energy received in accordance with the applicable rate schedule, net of any credits from prior months described below.

If the electricity exported to the distribution system by the customer-generator exceeds the electricity received from the distribution system over the billing period:

The surplus electricity exported to the distribution system shall be calculated by subtracting the kilowatt-hours received from the distribution system from the kilowatt-hours exported to the distribution system over the billing period;
The distribution utility shall use zero kilowatt-hours when calculating all charges that are based on kilowatt-hour usage;
The customer-generator shall be credited over subsequent billing periods (i.e. “banked”) for the surplus electricity exported to the distribution system and all associated kilowatt-hour-based charges;
For default service customers, if the surplus electricity production exceeds 600 kilowatt-hours after the March billing cycle, the customer-generator may elect, on an annual basis, to receive a payment from the distribution utility equal in amount to the economic value of accumulated surplus as calculated in accordance with the NHPUC 900 rules.

All charges that are not based on kilowatt-hours, including the customer charge and demand based charges, shall be billed in accordance with the applicable rate schedule.

For Alternative Net Energy Metering (customer-generators who did not receive a capacity allocation prior to September 1, 2017):

Non-bypassable charges shall be assessed based on the full amount of electricity received from the distribution system without any netting of electricity exports over the billing period.

If the electricity exported to the distribution system by the customer-generator exceeds the electricity received from the distribution system over the billing period:

The surplus electricity exported to the distribution system shall be calculated by subtracting the kilowatt-hours received from the distribution system from the kilowatt-hours exported to the distribution system over the billing period; and
The distribution utility shall use zero kilowatt-hours when calculating all charges, except non-bypassable charges, that are based on kilowatt-hour usage.
The customer-generator shall receive a monetary bill credit for net electricity exports over the billing period calculated at 25 percent of any distribution charges assessed on a per-kilowatt-hour basis, any transmission charges assessed on a per kilowatt-hour basis, and, for default service customers, the default service rate assessed on a per kilowatt-hour basis;
The monetary credits shall carry forward to subsequent billing periods until used;
If the monetary credit balance exceeds $100 as of the end of the March billing period, on an annual basis, the customer-generator may elect to receive a payment from the distribution utility.

All charges that are not based on kilowatt-hours, including the customer charge and demand based charges, shall be billed in accordance with the applicable rate schedule.

For Standard Net Energy Metering (customer-generators who received a capacity allocation prior to September 1, 2017):

If the electricity received by the customer-generator from the distribution system exceeds the electricity exported to the distribution system by the customer-generator over the billing period, the customer-generator shall be billed all applicable charges on all kilowatt-hours received by the customer from the distribution system, less a credit on default service charges, for those customer-generators on utility default service, equal to the metered electricity exported to the distribution system over the billing period.

If the electricity exported to the distribution system by the customer-generator exceeds the electricity received from the distribution system over the billing period:

The surplus electricity exported to the distribution system shall be calculated by subtracting the kilowatt-hours received from the distribution system from the kilowatt-hours exported to the distribution system over the billing period;
The distribution utility shall use zero kilowatt-hours when calculating all default service charges. The customer-generator shall be billed for all other applicable charges on all kilowatt-hours received by the customer from the electric distribution system;
The customer-generator shall be credited for surplus electricity exported to the distribution system over subsequent billing periods for default service charges only, for those customer-generators on utility default service. For default service customers, the customer-generator may elect on an annual basis to receive a payment from the distribution utility equal in amount to the economic value of the accumulated surplus as calculated in accordance with the NHPUC 900 rules.

All charges that are not based on kilowatt-hours, including the customer charge and demand based charges, shall be billed in accordance with the applicable rate schedule.

For Alternative Net Energy Metering (customer-generators who did not receive a capacity allocation prior to September 1, 2017):

If the electricity received by the customer-generator from the distribution system exceeds the electricity exported to the distribution system by the customer-generator over the billing period, the customer-generator shall be billed for all applicable charges on all kilowatt-hours received by the customer from the distribution system, less a credit on default service charges, for those customer-generators on utility default service, equal to the metered electricity exported to the distribution system over the billing period.

If the electricity exported to the distribution system by a customer-generator on utility default service exceeds the electricity received from the distribution system over the billing period:

The surplus electricity exported to the distribution system shall be calculated by subtracting the kilowatt-hours received from the distribution system from the kilowatt-hours exported to the distribution system over the billing period;
The distribution utility shall use zero kilowatt-hours when calculating all default service charges. The customer-generator shall be billed for all other applicable charges on all kilowatt-hours supplied to the customer from the electric distribution system;
Customer-generators who receive default service shall receive a monetary bill credit for surplus electricity exported, calculated at the default service rate assessed on a per kilowatt-hour basis;
The monetary credits shall carry forward to subsequent billing periods until used;
If the monetary credit balance exceeds $100 as of the end of the March billing period, on an annual basis, the customer-generator may elect to receive a payment from the distribution utility.

All charges that are not based on kilowatt-hours, including the customer charge and demand based charges, shall be billed in accordance with the applicable rate schedule.

For further information on Net Energy Metering and Group Net Metering, please refer to the NHPUC 900 rules.

Here are the rules and technical requirements for net metering set forth by the New Hampshire Public Utilities Commission. For customers whose applications for interconnection were deemed complete prior to September 1, 2017, PUC Rule 900 applies. For customers whose applications for interconnection were deemed complete on or after September 1, 2017, the Company tariff for Schedule QF (Rates Applicable to Qualifying Facilities), section entitled Net Energy Metering, applies.

The NHPUC established new rules regarding Group Net Metering effective January 8, 2015, which were modified by legislation effective July 2018.

For customers approved to be Group hosts by the NHPUC, payments will begin in the bill cycle following the first meter read date after your approval in accordance with the NHPUC rules. Payments for net excess generation will be made at full retail kWh rates and will include the energy service charge only for customers who are receiving energy service from Unitil.