National Grid
Certain types of Net Metering:
Allocating Net Metering Credits:
Qualifying Facilities:
Project Size and the Net Metering Cap:
Solar Renewable Energy Certificates:


  • What is net metering?
    1. Intermittent generators, such as solar and wind based generators, only produce electricity when their energy source is available (e.g. when the sun shines or the wind blows). With distributed generation (DG), intermittent generators are often connected behind the same utility meter as customer loads (e.g. HVAC, consumer electronics, lights) that can be turned off and on based on the needs of the customer. As a result, on-site electric power production does not necessarily match on-site electric power consumption (also known as the customer 'load' or demand') on a moment-to-moment basis. In Massachusetts, net metering allows these DG customers to financially balance out the total amount of energy imported with the total amount of energy exported over the course of a billing period (typically about a month). Then, the customer is only billed (or credited) for the net difference between these two amounts.

    2. Refer to the Net Metering page for a detailed description.

  • What is ISO-NE?
    1. ISO-NE stands for the Independent System Operator. It is responsible for managing the bulk power generation and transmission systems in New England.

  • What types of generating facilities can be used for net metering?
    1. Generating facilities that use renewable energy: solar, wind, and agricultural facilities are eligible for net metering.

  • My city or town gets electricity from a Municipality-Owned and Operated Electric Company. Could I Net Meter?
    1. This depends on whether or not your city or town follows the Net Metering rules that apply to Investor Owned Utilities.

    2. Please consult with your Local Electric Distribution Company. (Note: Net Metering Services will be administered through the Local Electric Distribution Company.)

  • Do I have to own the generating facilities that I install?
    1. No, the retail customer does not have to be the owner of the generation system.

  • Who is the Host Customer?
    1. The Host Customer is the account holder (the name on the electric bill). A Host Customer may or may not own the generating facilities served by their meter. Host Customers generate electricity on the Customer side of the meter.

  • What happens if I have a system behind my meter (i.e. I am the Host Customer) and I enter into a power purchase agreement with a third party?
    1. National Grid is not responsible for the terms and conditions of any agreement between the Host Customer and the third party system owner. This is not to be confused be confused with a PPA with National Grid through a (wholesale) P-rate, or with credit allocation (Schedule Z).

    2. For Simplified Applications, the Host Customer must fill out, sign, and submit an Exhibit H along with the remainder of the Interconnection Application documents. The sections that refer to the "Customer" in the Exhibit H should include information about the Host Customer (the legal entity listed on the electric utility bill). The sections that refer to the "Interconnecting Customer" in the Exhibit H should include information about the third party system owner.

    3. For Expedited or Standard Applications, National Grid will provide the Exhibit H as an attachment to the Interconnection Service Agreement. However, the Interconnecting Customer (i.e. third party system owner) must confirm that they have site control on the Interconnection Application and must provide contact information for the Host Customer on the Legal Information Document.

      Please see National Grid's Wholesale Energy Procurements website if you are interested in a PPA.

  • What if I generate less electricity than I use?
    1. If your generation system produces less energy than your facility/home uses during a billing period, you will only pay for the net amount of energy you draw from the grid.
      (Net Metering Tariff, Appendix A, Section 1.05)

  • What if I generate more electricity than I use?
    1. If your generating system produces more energy than your facility/home uses during that billing period, then your account will earn a credit that is equal to the net energy export amount (kWh) multiplied by the applicable charges. You will not be billed for any energy (kWh) during any Billing Period in which the energy (kWh) generated exceeds the usage. However, other charges will still be applied to your bill.
      (Net Metering Tariff, Appendix A, Section 1.05)

  • What if I am looking to sell my power via a transmission interconnection?
    1. If you wish to pursue a transmission interconnection as a Qualifying Facility (the local retail company would purchase 100% of output) then you would follow a state jurisdictional process which is administered by the (Distributed Generation) team.

    2. However, if you wish to sell the output to the market you would be required to interconnect under ISO-New England's Schedule 23 Tariff (if size is < 20 MW) which can be found at Documents and directions for submitting the interconnection application under Schedule 23 can be found at process is led by ISO New England and would consist of an initial scoping meeting to discuss regional/local planning variables, an overview of the proposed project, and next steps for the System Impact study phase.

      Without understanding the size of your project and whether there are any significant system impacts, a connection to National Grid's 115 kV (transmission) system would typically consist of tap line facility to a transmission substation consisting of a three-breaker ring bus, which would require about an acre of property adjacent to the Right of Way. This connection is estimated around $3-5 million dollars (depending on site location, etc), but the estimates would tighten during the study phase.

  • What if I have an inquiry on a site location?
    1. To discover the electric service characteristics of a proposed site location, customers must submit a Pre-Application Report Form Exhibit B to [email protected].This step is mandatory for all applications >=500kWAC.

  • If I want to apply for net metering, where do I begin the process?
    1. To apply for interconnection and net metering, please follow the Interconnection Process which includes completing a Schedule Z for allocation of net metering credits.

  • Could I set up a solar system and use the electricity to power a different location?
    1. No, the generation system must be on the same parcel of land as the Host Customer who is receiving the electricity. However, credits from the excess power generation can be allocated to different accounts. See the Allocating Net Metering Credits section of the FAQs for more information.

  • Which load zone am I in?
    1. Your load zone is based on the geographic location of your facility. Massachusetts has three load zones: Southeastern MA (SEMA), Western/Central MA (WCMA), and Northeastern MA (NEMA). To find your load zone you can visit shared load zones or visit your account and select "View Your Account". Your load zone information will appear in the Account Details section.

  • Are customers required to install production meters?
    1. According to Section 1.03 on the MA Net Metering Tariff, Host Customers with a Class II or III Net Metering Facility shall install at the Host Customer's expense revenue-grade meters to measure the generator's kilowatt-hour ("kWh") output. Unless otherwise agreed in writing with the Distribution Company, the Host Customer will provide the actual metered output to the Distribution Company twice per calendar year: on or before January 31 and on or before September 30.

  • Who pays for the revenue meter?
    1. As stated in section 8.1 of the interconnection Tariff, the Company shall own the meter and the Interconnecting Customer shall pay the Company a monthly charge to cover taxes, meter maintenance, incremental reading and billing costs, the allowable return on the invoice cost of the meter and the depreciation of the meter.

  • Does my project need a phone line connected to the utility meter?
    1. Only if the project is above 60 kW and exporting power will the customer be required to provide a phone.

  • When am I eligible to receive net metering credits?
    1. You are eligible after:

      1) You receive approval from the Net Metering System of Assurance (refer to;

      2) Your standard meter has been replaced with a bi-directional meter (i.e. net meter); and

      3) You have received the formal "Authorization to Interconnect" e-mail or letter from National Grid.

Certain types of Net Metering:
  • What is an Independent Power Producer (IPP) and standalone generation?
    1. For the utility company, a stand-alone generating system is a grid-connected generating system that does not have any (non-parasitic) load behind the same meter. This is not to be confused with an isolated (or backup) generating system, which does not operate in parallel with the utility grid.

    2. Stand-alone generating systems are referred to as Independent Power Producers (IPP) (i.e. a generating system that uses little or no power and was constructed solely for the purpose of generating electricity).

  • What is remote net metering?
    1. While the terms "Remote" or "Virtual" net metering are not used in Massachusetts, Massachusetts' net metering regulations allow for benefits similar to programs in other states that use this terminology. In Massachusetts, customers with net metered distributed generation systems may allocate net metering credits to other National Grid electric accounts within the same ISO-NE load zone. This is allocation is determined when the customer submits a completed Schedule Z form to National Grid along with the appropriate Interconnection Application materials.

  • What are the definitions of a Unit and a Facility?
    1. On August 24, 2012 the MA Department of Public Utilities (D.P.U.) issued an order in 11-11-C on Definition of Unit and Facility where they limited each single parcel of land to one "host" costumer. On July 1, 2013 the MA D.P.U. offered additional clarification regarding the definition of a Facility. Please refer to the Massachusetts DPU Net Metering FAQ website for more information.

Allocating Net Metering Credits:
  • How is Net Metering credits handled for a G-3 Large Commercial Customer?
    1. G3 accounts have Time-of-Use metering that records energy imported or exported during on/off-peak periods, as defined by the rate. Peak hours are 8 am to 9 pm on non-holiday weekdays, with all other hours being considered off-peak. If a G3 customer exports during the peak hours, the Peak Net Metering Credit is calculated at the on-peak rate. Similarly, if a G3 customer exports during off-peak hours, the Off Peak Net Metering Credit is calculated based on the off-peak rate.

  • Is it a requirement to fill out Schedule Z (Net Metering Allocation form)?
    1. No. Schedule Z is only required for customers who want net metering.

  • How often could I submit a Schedule Z form or modify my Schedule Z allocations?
    1. Interconnecting Customers are allowed to submit a final revised Schedule Z form prior to receiving the "Authorization to Interconnect"(and then up to twice per year after receiving the Authorization to Interconnect).

  • What is Exhibit H?
    1. The Exhibit H is an agreement between National Grid and the Host Customer (the named legal entity on the electric billing account) to interconnect a third-party generation unit behind the Host Customer's meter.

    2. The Exhibit H must be completed when the retail customer is not the owner and operator of the proposed generation system. (For simplified applications, this must be submitted with the initial application. For all other applicants, the Exhibit H will be included in the Interconnection Service Agreement.)

  • As the Host Customer, where can I find the net metering credits on my bill?
    1. Customers that net export power over the billing period will notice the following differences on their bill:

      1) The current meter reading will be lower than the previous reading.

      2) The total usage will appear as a negative number.

      3) Net Metering Credit will be a line item in the Delivery section of the bill.

    2. If the Net Metering Credit exceeds the total of the other charges on the bill, the "Current Charges" will be negative.

    3. If the Net Metering Credit does not exceed the total of the other charges, then the "Current Charges" will be positive.

  • How much of the credit will each "target account" receive?
    1. Credits will be allocated from the Host Customer to "target" customer(s), as directed in Schedule Z on a percentage basis only.

  • How are net metering credits calculated?
    1. MA-Please refer to the Massachusetts Net Metering Tariff (Section 1.06 of the Net Metering Provision section) to see how net metering credits are calculated.The net metering tariff can be found on the Interconnection Documents page.

    If you are: Then multiply net export (in kWH) by:
    Municipal or governmental entity and own solar from 1.01- 2 MW Distribution + Basic Service + Transmission + Transition
    Anyone owning wind or solar from 0 - 1MW, inclusive Distribution + Basic Service + Transmission + Transition
    Agricultural facility between 0 - 1 MW, inclusive Distribution + Basic Service + Transmission + Transition
    Agricultural facility between 1.01 MW - 2 MW, inclusive Basic Service + Transmission + Transition
    Anyone with wind, solar between 1.01 MW - 2 MW, inclusive Basic Service + Transmission + Transition
    Neighborhood and own solar or wind 0 -2 MW, inclusive Basic Service + Transmission + Transition
    Facility that is not wind, solar or agricultural under or equal to 60kW Average Monthly Clearing Price at the ISO-NE

  • What are the different net metering classes?
    1. Class I: any facility that is 60 kW or less

    2. Class II: solar, wind, anaerobic digester, or agricultural facility that is greater than 60 kW and less than or equal to 1 MW

    3. Class III: solar, wind, anaerobic digester, or agricultural facility that is greater than 1 MW and less than or equal to 2 MW

    4. Agricultural

  • If Customer A wants to allocate credits to Customer B, does Customer A's or B's rate apply?
    1. Net Metering Credits are calculated at the rate of the Host Customer (Customer A in this example). The resulting dollar amount would be moved to and shown on Customer B's account, generally in the following month.

  • I am the Host Customer for my project and I have chosen to allocate my net metering credits via a Schedule Z. Would the target customers on Schedule Z see how the credits are allocated, specifically which percentage each one is receiving?
    1. No, the customers cannot see what percentage of net metering credits they are receiving; they are only able to view the dollar value of the net metering credit they have received.

  • Could I ever receive a check for my net metering credits?
    1. If the generating facility qualifies for Class III (1MW to 2MW) net metering, the distribution company may elect to pay for the credits by check. This will be determined on a case by case basis once credits have been generated on the account.

  • Will all credits on my account be refunded to me via check if at some future time, while under the Interconnection Service Agreement, I sell my property?
    1. Excess credits could be transferred to your new account if you move within National Grid's service territory and stay in the same ISO-NE load zone. If you move out of state or to another utility or load zone, your Net Metering Credits are forfeited.

  • What happens if I have excess credit at the end of the year?
    1. Customers who accrue a credit on their electric bill will continue to roll the credit forward indefinitely.

  • Could I allocate to a National Grid Gas account?
    1. No. Allocation of credits is not allowed to gas accounts per the Net Metering Tariff. Currently, there is no mechanism in the tariff.

  • Once the cap is reached, is there a way for on-site solar facilities to interconnect?
    1. Yes. The project would be considered a Qualifying Facility (QF). National Grid would purchase output from them at the ISO-NE hourly wholesale clearing price. This differs from net metering where the utility purchases at the retail price. This also differs from net metering in that the customer cannot allocate credits (Schedule Z).

  • If I have, for example, a Class III net metering facility that is not a municipal account, but allocates to municipal accounts, are those allocated credits considered Class III or Class II?
    1. It will be considered a Class III facility. However, if allocating to municipal accounts then the customer would need to follow the state approval process by filling out Appendix C and viewing Order Adapting Model Net Metering Tariff. Customer should submit the state approval of Appendix C with the application to National Grid.

Qualifying Facilities:
  • What is a Qualifying Facility?
    1. A Qualifying Facility is a renewable energy generating facility that receives a special rate and regulatory treatment. They can either be a small power production facility (less than or equal to 80 MW) or a cogeneration facility (produces electricity and heat).

  • What is the Qualifying Facility Power Purchase "Rate P" ?
    1. It is a rate specific to Qualifying Facilities determined by ISO-NE.

  • How is output metered and purchased at a Qualifying Facility?
    1. QFs have their output metered hourly and this energy is purchased at hourly rates equal to the wholesale payments received by National Grid from ISO-NE. These rates are generally significantly lower than retail rates. Each month the customer will receive a check from National Grid.

Project Size and the Net Metering Cap:
  • A Class III Net Metering facility can be up to 2 MW. What is the maximum size for a project?
    1. Class III Net Metering facilities are limited to 2 MW unless the generation is owned or operated by a Customer who is a municipality or other governmental entity. In this case, the total system size of the facilities can exceed 2 MW as long as they are comprised of multiple generation units each less than or equals to 2 MW, respectively. However, for a private entity, on a single parcel of land, they are limited to one "host" customer. Please click the Definition of Unit and Facility link for more information.

  • What is the Net Metering "Cap"?
    1. According to Massachusetts law, (as of August 3rd, 2012) the aggregate total of generating facilities taking net metering service is capped at 3% of the utility's historic peak load. Governmental entities are similarly capped at 3% of retail load.

  • Does the government entity have to own the distributed generation system or simply be a party to the transaction/receiver of credits in order to fall under the 3% government net metering cap?
    1. The Host customer must be in the name of the government entity. In order to fall under the government cap, the customer will need to file Appendix C as public facilities can not infringe on the private net metering cap. See Section 1.12 in the Net Metering Provision. Appendix C is an electronic application form for public entities, which may only be submitted electronically to Department at: [email protected]. Paper copies of this form will not be accepted.

Solar Renewable Energy Certificates:
  • What is a SREC?
    1. An SREC is a Solar Renewable Energy Certificate, which represents the renewable and/or environmental attributes associated with electricity that is produced by solar generators. An SREC is created for every megawatt-hour of solar electricity created. In states with SREC legislation, the Renewable Portfolio Standard (RPS) mandates that distribution companies buy a certain quantity of SRECs each year.

    2. Note: A Renewable Energy Certificate (REC) is similar to an SREC, but it is generally associated with electricity produced by non-solar renewable technologies, such as wind turbines or anaerobic digesters.

  • If the distribution company is buying power, is it also entitled to the system's RECs for no extra charge?
    1. Utilities are not automatically granted the RECs (Renewable Energy Certificates). The RECs are separate from the power the distribution company is buying. (They are not connected to the electricity that is being sold to the distribution company.)

  • I'm moving into a house with a self-generation system already installed. What do I need to do to benefit from Net Metering?
    1. If you are the new homeowner you would need to agree to the terms and conditions set forth in the original Interconnection Service Agreement (ISA).

    2. You also need to:

      1) Understand how your generation system works.

      2) If possible, ensure that the transfer of ownership is appropriately documented during the sale of the house. (Verify the status of any third party ownership of the generation system.)

      3) Contact National Grid to request an updated Interconnection Service Agreement (ISA).

  • Where can I find my account number and meter number?
    1. This information can be found at the top of your electricity bill.

  • I installed a solar system, why is my bill so high?
    1. This depends on a number of factors. If the weather is not favorable to your generating facility (eg.: little sun for solar systems and insufficient wind for turbines), then your system will not be supplying power to its full potential. Similarly, clouds that block the sun will reduce the power output from solar panels. Choosing the right location for your generating facility is critical.

  • Are there any tax credits or rebates for installing a renewable-energy system?
    1. A comprehensive list of tax credits, rebates, incentives and more can be found at

  • Where can I find a Form W-9 for National Grid?
    1. Our W-9 forms can be found at /shortcut_w9.asp

  • Still have questions?
    1. Email: [email protected]