Net Metering

This figure is measuring the energy in kilowatt-hours (kWh) passing from our electric infrastructure through the meter into the home. This is not the total amount of energy your home is using, but only the amount you are drawing off the wires coming down your street.

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.

As of early 2025, Generating Facilities with a nameplate rating equal to or less than 25 kW are no longer required to apply for registration of a cap allocation with the MassACA.  Generating Facilities with a nameplate rating greater than 25 kW 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.

Changes to net metering regulations:

Implemented in 2025, these changes were made by the Massachusetts Department of Public Utilities (“DPU”) in 2024 based upon directions included in the Massachusetts 2021 Climate Act and 2022 Clean Energy Act. Please note that no action is required by you at this time. Read the official letter on General NEM updates.

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 or equal to 25 kW 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:

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. Beginning April 1, 2025, eligible net metering host customers earning Market Net Metering Credits can allocate credits through a Schedule Z to transfer net metering credits to electric accounts within the Commonwealth. 

Net metering credits cannot be transferred to other customer accounts after they have been earned, except in cases where the host customer has terminated service with Unitil. Upon final termination of a host account, the customer has 12 months to request transfer of the excess net metering credit balance to another electric account in Unitil Service territory.

Current Numbers:

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 order to guarantee a position under the net metering Caps, all non-Cap exempt customers must apply for allocation under the Massachusetts System of Assurance for Net Metering.

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 your Interconnection Program Portal.

• Download Schedule Z Net Metering Allocation Spreadsheet (Excel)
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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)

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:

1. 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;
2. The distribution utility shall use zero kilowatt-hours when calculating all charges that are based on kilowatt-hour usage;
3. 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;
4. 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:

1. 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;
2. 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;
3. 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.

• NHPUC Requirements (PDF)
• Applicable Tariff

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.

• PUC 900 Rules (PDF)