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Net metering allows customers to offset their energy use and transfer energy back to their electric companies in exchange for a credit. If you have a solar or another renewable energy facility, and your electric company allows it, you may be able to net meter. Want to learn more about how net metering works?
If you are a customer of a regulated electric company (Eversource, National Grid, or Unitil), you may net meter. Net metering allows you to generate your own electricity to offset your electricity usage. Common examples of net metering facilities include solar panels on a home or a wind turbine at a school. These facilities are connected to a meter, which measure the net quantity of electricity that you use. When you use electricity from the electric company, your meter spins forward. When you generate excess electricity and “export” electricity to the electric grid, your meter spins backward.
Massachusetts does not differentiate between behind-the-meter net metering (electricity generation consumed on the same site it is generated) versus virtual net metering (electricity generation consumed at a site other than where the electricity is generated). For most purposes, including credit calculation, there is no difference between net metering and virtual net metering.
Your net metering facility may use any type of generating technology, regardless of whether it is a renewable technology, if it is smaller than or equal to 60 kilowatts (kW). G.L. c. 164, § 138; 220 CMR 18.00. If your net metering facility uses wind, solar, or anaerobic digestion technology, then it must be:
State law requires that the electric companies must have separate net metering caps for public and private net metering facilities in the general net metering program (GP). St. 2010, c. 359, s. 29.00. Each GP cap is equal to a percentage of each electric company’s highest historical peak load, which is the most electricity consumed by the electric company’s customers at any one time.
As of April 11, 2016, the caps are:
Private Cap (7%)
Public Cap (8%)
National Grid Massachusetts Electric Company
National Grid Nantucket Electric Company
NSTAR Electric Company d/b/a Eversource Energy
Western Massachusetts Electric Company d/b/a Eversource Energy
Unitil d/b/a Fitchburg Gas and Electric Light Company
Under the GP, once an electric company fills its net metering cap, new customers that require space under that cap cannot participate in net metering. Note that cap exempt facilities (cap exempt facilities are those with a nameplate rating less than ten kilowatts on a single-phase circuit or 25 kilowatts on a three-phase circuit) will be able to net meter even if the relevant cap is full. 220 CMR 18.02, 18.07(5).
Public and private net metering facilities have different size limits and may generate different credit values. For more information on public facilities, please see Designing Net Metering Facilities.
State law also requires that the electric companies have a separate cap for facilities participating in the small hydroelectric power net metering program (SHP) that has a combined capacity of 60 MW. St. 2016, c. 188, s. 10. Each SHP cap share is equal to an electric company’s load measured in megawatt-hours in calendar year 2016. D.P.U. 17-10-A. The SHP cap shares will be determined in the D.P.U. 18-04 compliance filings.
Under the SHP, new customers must obtain a cap allocation to participate even if they are less than ten kilowatts on a single-phase circuit or 25 kilowatts on a three-phase circuit. Under the SHP, once an electric company fills its net metering cap, new customers that seek to participate in net metering must apply for a cap allocation from the relevant GP cap unless they are a cap exempt facility.
Net metering credits can offset the delivery and supply portions of your electric bill, as well as customer charges. You may use net metering credits to decrease your electricity bill to zero dollars and zero kilowatt hour (kWh) usage. G.L. c. 164, §§ 138, 139. 220 CMR 18.04.
Customers who net meter are billed for their net consumption of electricity.
Net monthly consumption = (total electricity consumed in a month) - (total electricity generated in a month).
To determine your credit value:
Size of Private Facility
Size of Public Facility
Class I net metering facility
60 kW or less
60kW or less
Class II net metering facility
more than 60 kW but less than or equal to 1 MW
more than 60 kW but less than or equal to 1 MW
Class III net metering facility
more than 1 MW but less than or equal to 2 MW
more than 1 MW but less than or equal to 10 MW
Small Hydroelectric Program
Size of Facility
Small hydroelectric net metering facility
2 MW or less
Size of Private Facility
Size of Public Facility
Small Hydroelectric Program
Size of Facility
In April 2016, the Solar Energy Act created different net metering credits values for solar net metering facilities. Before the Solar Energy Act, solar net metering facilities generated standard net metering credits under the old regime. After the Solar Energy Act, certain solar net metering facilities generate market net metering credits under the new regime.
220 CMR 18.04 and Appendix A of your electric company’s net metering tariff will tell you whether your facility will generate standard net metering credits or market net metering credits.
All solar net metering facilities that are not cap exempt will generate market net metering credits for 25 years from the date of authorization to interconnect to the electric grid. 220 CMR 18.04.
The following solar net metering facilities generate market net metering credits equal to 100% of the net excess kilowatt hours:
For specific information about net metering credits for your net metering facility, contact your electric company.
The host customer of a net metering facility determines what happens to the net metering credits a facility generates by submitting a form called Schedule Z to the electric company. A host customer may change Schedule Z no more than twice in one calendar year, unless there is mutual agreement to change it more often. Contact your electric company for more information about Schedule Z. G.L. c. 164, § 139(b)(1).
As a host customer, you may use net metering credits to offset your bill from your electric company. You may also assign net metering credits to other accounts (even if they are not your accounts) as long as all the accounts are:
If you allocate net metering credits to a public entity, there is no effect on the public entity’s 10 MW limit. A public entity may receive an unlimited amount of net metering credits with no effect on its 10 MW limit. The capacity of a net metering facility within the public cap only affects the host customer’s 10 MW limit.
Time of use (TOU) rates are rate designs with a peak and off peak rate. Commercial and industrial electric customers may be on a TOU rate, provided that the customer meets the requirements to be on the TOU rate. For more information on the TOU rate, consult the electric company’s TOU tariff. Only NSTAR Electric (Eversource Energy) and National Grid offer a TOU rate for residential customers. If you are on a TOU rate, you will generate net metering credits based on the TOU rate.
The design, installation, and interconnection of a net metering facility can be complex. We recommend that you consult a professional. We do not regulate installers and developers and cannot endorse any companies.
It is your responsibility to make sure that your net metering facility complies with the net metering rules and regulations. We highlight some of the important rules below. However, you should read the Important Resources provided below to make sure you understand all of the rules and regulations associated with net metering.
The Single Parcel Rule defines a net metering facility as “the energy generating equipment associated with a single parcel of land, interconnected with the electric distribution system at a single point, behind a single meter.”
According to the Subdivision Rule if you want to install a net metering facility on a parcel of land that was the result of a subdivision occurring after January 1, 2010, you must petition the DPU.
To design a net metering facility participating in the GP that complies with the DPU’s rules and regulations, please keep the following information in mind:
If you cannot design a net metering facility that complies with the DPU’s net metering rules and regulations, you may be granted an exception.
The electric companies may grant exceptions to the Single Parcel Rule on the basis of optimal interconnection. The exceptions may include multiple interconnection points and multiple meters for a single facility. D.P.U. 11-11-E. For more information on submitting a petition to the DPU, visit Petitioning the DPU.
Note that small hydroelectric net metering facilities participating in the SHP are not subject to the Single Parcel or Subdivision Rules.
Before designing your net metering facility, you will want to read the following resources at a minimum:
To access these resources, go to the Net Metering Filings webpage.
To be in the public cap under the GP, your facility must be a Class II or III:
If your facility cannot meet the criteria listed above, your facility belongs in the private net metering cap under the GP. A facility cannot be in both caps at the same time.
Public net metering facilities may be up to 10 MW. However, each unit must be at least 60 kW and cannot exceed 2 MW. G.L. c. 164, §§ 138, 139(f); 11-11-C at 15.
Only the DPU can classify participants as “municipalities” or “other governmental entities,” that is to say, as public entities. There is no self-designation. To receive this classification (also called a public ID number), a participant must file An Application for Municipality or Other Governmental Entity with the DPU electronically.
There are two different situations where a public entity (either municipality or other governmental entity) would need to obtain a classification number:
When applying for a cap allocation with MassACA, the AC capacity of a solar net metering facility is 80% of the facility’s DC rating at standard test conditions. This means that the AC capacity that is used to determine your net metering cap allocation may be different than the “as-built” AC capacity.
Both the host customer and all offtakers must be public entities with a public ID number provided by the DPU.
The DPU relies on the registry of deeds to determine parcel boundaries. The DPU does not rely on GIS documentation to determine parcel boundaries. If you have questions about whether and how your parcel boundary changes affect your net metering facility, contact your electric company first before contacting DPU staff.
If you are receiving market net metering credits, the 60 percent only applies to excess kilowatt hours generated.
The DPU approved Eversource Energy's request for an MMRC in D.P.U. 17-05-B at 100-156. To date, National Grid and Unitil have not filed an MMRC proposal with the DPU.
The purpose of an MMRC is to ensure that all electric company customers contribute to the fixed costs of ensuring reliability, proper maintenance, and safety of the electric distribution system. St. 2016, c. 75, § 9.
The electric companies must file their MMRC proposals in (1) their base distribution rate proceeding; or (2) a revenue neutral rate design filing that is supported by appropriate cost of service data across all rate classes. St. 2016, c. 75, § 9.
The DPU may approve an MMRC that:
The DPU may only approve a proposal for an MMRC after the aggregate nameplate capacity of installed solar generating facilities in the Commonwealth is equal to or greater than 1,600 MW (MMRC Date). The DPU established the MMRC Date as May 1, 2017. D.P.U. 16-64-G at 20. The DPU must conduct a full adjudicatory proceeding when reviewing proposals for an MMRC, which shall include at least 1 public hearing and an opportunity for public comments. St. 2016, c. 75, § 9.
This net metering guide was created to provide an overview of net metering. For more information on net metering visit the net metering homepage. You may also find the following resources helpful:
MassACA (also known as the System of Assurance of Net Metering Eligibility) was created by the DPU to:
MassACA started accepted applications for a cap allocation (ACA) on January 24, 2013. For more information about MassACA or to review the aggregate capacity of net metering facilities in Massachusetts visit the MassACA website. For tips on applying for a cap allocation, visit our "how to" page.
Many net metering questions can or must be answered by your electric company (e.g., installing net meters, the interconnection process, qualifying for an optimal interconnection exception, etc.). Please contact your electric company for questions related to interconnection, including whether or not your facility qualifies for an optimal interconnection exemption.
Massachusetts Electric Company and Nantucket Electric Company, each d/b/a National Grid
Contact: email (email preferred) or customer service at (800) 322-3223
Contact: Bruce Kim at (781) 441-8285 or by email
Fitchburg Gas and Electric Light Company d/b/a Unitil
Contact: (888) 301-7700
Contact: Cindy Janke at (413) 585-1780, (413) 787-1087, or by email
You can also visit the following webpages for more information on interconnection:
If you have an interconnection dispute, you must try to resolve it directly with your electric company. If the dispute cannot be resolved, please provide the following information to the DPU's Consumer Division online, by phone, mail, fax or email:
If you have a dispute with an installer, seller, or developer and wish to take formal action, contact the Attorney General’s Office, the Better Business Bureau, or consider your legal options.
Please contact the DPU for answers to specific questions about the net metering rules and regulations.
Please contact the Administrator of the System of Assurance for questions related to applying for a cap allocation.