Distributed Generation and Interconnection in Massachusetts
Updated Apr 15, 2014, 12:16 PM
Distributed Generation and Interconnection in Massachusetts
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Net Metering

Net metering allows customers with distributed generation systems, typically wind or solar, to be compensated when their systems generate more electricity than the customer is using onsite. Effectively, the meter "runs backward" whenever a customer's distributed generation system is producing more power than is being consumed onsite.

At the end of each month, on-site generation is credited against any electricity that the customer consumed from the grid. If the customer has net excess generation at the end of the month, the customer receives a credit on his or her utility bill.  For an overview of net metering, please take a look at these Frequently Asked Questions.

More comprehensive information is available at the DPU's new net metering web page and on the utility web pages covering net metering (see links in the right sidebar).

Net metering eligibility

Massachusetts has three classes of net metering facilities:

 Class      Size  Generation Type
 Class I    
  ≤ 60 kW
Any generator
 Class II
 > 60 kW; ≤ 1 MW
Agricultural, solar, wind, or anaerobic digestion
 Class III
 > 1 MW; ≤ 2 MW
Agricultural, solar, wind, or anaerobic digestion

For government entities, the size limit applies on a per-unit basis, rather than per facility. For example, a government entity  with two 1 MW wind turbines would be classified as Class II, but a private entity with those two turbines would be classified as a Class III.

Massachusetts also allows "neighborhood net metering" for neighborhood-based Class I, II, or III facilities that are owned by (or serve the energy needs of) a group of 10 or more residential customers in a single neighborhood and served by a single utility. The neighborhood facility may also serve additional customers (including commercial), as long as the base requirements are met.

All net-metered facilities must be behind a customer's meter, but only a minimal amount of onsite load is required.

Net metering credits

At the end of each billing period, net metering customers receive a credit on their utility bill based on the excess kilowatt-hours (kWh) produced by their net-metered system. The calculation of the credit varies by facility class and customer type.

Credits for renewable generation (using net excess or "exported" generation for the billing period)

   Credit includes the following kWh-based billing elements
 Class          Default Service
 Distribution  Transmission  Transition
 Class I
 X*  X  X  X
 Class II
 X  X  X  X
 Class III
 X  Gov't only
 X  X

Net metering customers remain responsible for customer charges, kW-based charges, and system benefit charges.

* Non-renewable generation (for example, from Class I cogeneration facilities) is credited only at the average monthly clearing price at ISO New England rather than the Default Service price without any of the other kWh-based elements.

View examples of how net metering credits would apply to a typical residential customer bill using two scenarios.

Net metering customers may direct their utility to allocate the net metering credits to other customers that are in the same utility service territory and ISO-NE load zone (a policy called "virtual net metering"). For Class III facilities, the utility has the option to purchase the net metering credits rather than allocating them.  See your zone by zip code or street address at the ISO-NE Dispatch Zone Determination Website.

Net metering caps

The total amount of net metering capacity on a utility's system is limited to 6% of the system peak load, 3% for net metering on private facilities, and 3% on public facilities such as municipal buildings. Massachusetts has created a System of Assurance of Net Metering Eligibility to enable customers that are developing distributed generation systems to reserve space under the cap. The MassACA.org website provides information about the space available under each utility's cap (see the link entitled "Public/Private Cap Info").

Small, renewable distributed generation systems are exempt from the cap. The exemption applies to renewable generators 10 kW or smaller in a single-phase circuit and 25 kW or smaller on a three-phase circuit.

How to apply

Apply for net metering by submitting a Schedule Z along with your application to interconnect, which is available from the net metering pages on each utility website (see links in right sidebar). In addition, the Massachusetts Department of Public Utilities requires all public entities to apply here for classification as a public entity.
Additional information
DPU net metering regulations
System of Assurance of Net Metering Eligibility

 

Utility forms and tariffs
National Grid
NSTAR
- Net metering tariff
- Net metering cap
- Schedule Z
- Net metering FAQ
WMECo
Unitil

 

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