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Net Metering Frequently Asked Questions

Below you will find answers and information pertaining to common questions about net metering and the safe interconnection of generators to the NSTAR electric power system.

Such interconnections include photovoltaic arrays (solar panels), mini-turbines, wind turbines, cogeneration units and micro turbines, to name a few.

All regulations and fees have been filed and approved by the Massachusetts Department of Public Utilities (DPU). More information on net metering can also be found on the DPU's web site.

Who qualifies for Net Metering?

  Class I Class II Class III
Customer Class Solar, Wind or Agricultural Solar, Wind or Agricultural Solar, Wind or Agricultural
kW 60 kW or less Greater than 60 kW up to 1,000 kW Greater than 1,000 kW up to 2,000 kW
Net Metering
Credit Calculation
Credit excess generation, by TOU period if applicable, for all kWh rate components including default service except DSM & renewables. Credit excess generation, by TOU period if applicable, for all kWh rate components including default service except DSM & Renewables. Credit excess generation, by TOU period if applicable, for all kWh rate components including default service except Distribution, DSM & Renewables.
Calculation Exceptions     If municipal then also credit distribution kWh rate.
Limits Aggregate capacity shall not exceed 3 percent of NSTAR’s distribution peak for private facilities and 3 percent for municipal facilities.

When am I eligible to receive net metering credits?
You will be eligible to receive net metering credits only after your unit is authorized to be online and you have provided:

  • Evidence that you have received a Cap Allocation from the Administrator of the System of Assurance (see www.massaca.org). Simplified systems (less than 10 kW AC single phase and less than or equal to 25 kW AC three phase) are exempt from the Cap Allocation requirement;
  • A complete and accurate Schedule Z;
  • For agricultural net metering facilities, a determination from the Commissioner of the Department of Agricultural Resources that a business is an agricultural business and that the net metering facility is operated as part of that business; and
  • For anaerobic digestion net metering facilities, a determination from the Department of Energy Resources (“DOER”), in coordination with the Department of Environmental Protection (“DEP”), that the facility qualifies under DOER’s regulations as a Class I renewable energy generating source pursuant to DOER’s Renewable Portfolio Standards regulations.

For billing, what are the two types of Net Metering accounts?
There are two types of customers, host and allocatee. Host customers may produce excess generation.Credits from this generation may be used within the same account, or transferred to allocatee accounts (via a Schedule Z form).

I’m a Host Customer. Where would I find my net metering credits on my net metering bill?
Your net metering credits will appear under “Other Charges or Credits” on your current month’s bill. The line item will state “Net MtrCrdt" with both the kWh usage and the rate displayed.

I’m a Host Customer. Where on my net metering bill would I find the amount of net metering credits that were transferred to an Allocatee?
On the Host Customer bill, the section, "Other Charges or Credits," contains the detail for the individual "Transfer Amounts" of net metering credits that ware being transferred during the current month to the Allocatee accounts as specified in the Host Customer's completed Schedule Z form. It also details any remaining Net Metering Credit.

How do I know the amount of excess generation for the current bill?
Finding the difference between the actual read on last month's bill and the actual read from the current bill would give you the number of kWh used to calculate the net metering credit for the current month. This information can be found under "Electricity Used" on your bill as “Billed Use." A net negative number for Billed Use indicates excess generation.

How is the total amount of the net metering credit calculated or determined?
In general, the net metering credit is calculated by multiplying excess generation (kWh) by the appropriate rate for each of the following charges:

  • Default service fixed charge.
  • Distribution charge.
  • Transmission charge
  • Transition charge

For a summary of the calculations, please see the table in question 1. More information is also available in the Net Metering tariff.

How do I know how much of the net metering credit is available to be allocated each month?
The amount available to be allocated is equal to the current month's net metering credit less any Host Customer's charges. The calculation for the net metering credit is a line item under "Other Charges or Credits" and host customer charges are indicated under "Cost of Electricity." More information is also available in the Net Metering tariff.

What percentage of the net metering credit is applied to delivery charges versus supplier charges?
The net metering credit is split between the delivery charges and the supplier charges 50/50 (or 35/65 for low-income customers) if there is a supplier balance.

I’m an Allocatee Customer. Where would I find my net metering credits on my net metering bill?
On the Allocatee Customer’s bill, the section, "Other Charges or Credits," contains the amount of the net metering credit transferred from the Host Customer’s account (“Transfer Amount”), and the amount of that credit that was applied towards the Allocatee’s supplier balance (“Transfer to Supplier Bal"), and any associated sales tax and late payment charges as outlined in the example below.

Why has the "Other Charges and Credits" amount on the Host Customer’s bill been different from credits appearing on the Allocatee’s bills for the same month?
Prior to April 2014, credits earned by the host account were not reported as a transfer on the Allocatee customer's bill until the month after the Host customer credit was reported. This process has been changed, and the net metering credit earned by a Host customer during a billing cycle is applied to the electric bill of the Allocatee customers that same billing cycle. Host customer credits are applied to their account in the same billing cycle also.

How much of the credit will each Allocatee receive?
NSTAR requires the Host Customer to have an approved Schedule Z on file. The Allocatees and allocation percentages are designated on the Schedule Z form by the Host Customer. The Host customer bill will reflect the allocation percentages, Allocatee account numbers and credit amounts in the "Other Charges or Credits" section.

If I have a large credit balance due to net metering credits, can I receive a check?
All credits are either posted to a host customer’s account or allocated to designated customers. Per the tariff, checks may be issued, at NSTAR's discretion, for Class III customers only. For a Class III Net Metering Facility, the Distribution Company may elect to purchase Net Metering Credits from the Host Customer, rather than allocating such Credits. The Distribution Company must provide written notice to the Host Customer of its election to either purchase or allocate Net Metering Credits within 30 days of the Host Customer’s request for Net Metering Services.

For Net Metering Credits purchased under this provision, the Distribution Company will make payment by issuing a check to the Host Customer each Billing Period, unless otherwise agreed in writing with the Host Customer. In addition, the Distribution Company shall continue to purchase such credits for so long as the Host Customer takes service under this tariff or as mutually agreed in writing by the Distribution Company and the Host Customer.

Class I and Class II customers with large credit balances should complete a new Schedule Z form to allocate excess net metering credits to additional electric accounts. Per the tariff: For any Billing Period that a Host Customer earns Net Metering Credits, the Distribution Company shall allocate Net Metering Credits by applying them to a designated Customer’s account. The Distribution Company shall carry forward, from Billing Period to Billing Period, any remaining Net Metering Credit balance.

How many times may I submit a new Schedule Z?
A new schedule Z may be submitted twice in a calendar year.

Who qualifies as a municipal customer?
Only the Department of Public Utilities (DPU) can classify participants as municipalities, other government entities or public entities. There is no self-designation available.

To receive this classification, a participant must file an application with the DPU. The application and instructions are available on the MassACA web site. Once approved, the DPU will assign a public entity classification number.

When is a public entity required to obtain official classification from the Mass. Department of Public Utilities?
There are three situations where a municipality or other government entity would need to obtain a classification number from the DPU:

  • The public entity wants to enroll in net metering.
  • The public entity is already taking advantage of net metering.
  • The public entity is going to receive net metering credits from a different public entity.

If I qualify, how soon would I get a check for the net metering credits? (Class III customers)
It usually takes about three weeks from the point Billing receives the meter reads to the processing of a check by Accounts Payable.

Can I allocate to an NSTAR Gas account?
No. Net metering credits can be allocated to other electric accounts within the service territory and ISO load zone of the Host Customer account consistent with Section 1.07 of the Net Metering tariff.

Can a customer close their account to cash out the net metering credits?
No. If a customer closes their account, the residual net metering credit will be allocated to all NSTAR customers.

Can a customer partially cash out their credits?
Net Metering Credits will not be cashed out either in full or partially. The only exception to this is Class III customers who were approved by NSTAR to receive a check.

Are net metering credits transferred to basic service and/or alternate supplier charges?
Yes, if the net metering credit is large enough, it is used to pay off the Host Customer’s distribution and supplier balances in full. If the net metering credit is not large enough to fully pay off the Host Customer’s bill and there is a supplier balance, the credit is split 50/50 for non-low income customers and 35/65 for low income customers. If there is no supplier balance, e.g. the current supplier balance is zero, and the customer does not allocate the credit, it remains on the distribution portion of the account.

If the Host is allocating, we pay the Host account to zero and allocate credits based on the percentage listed in Schedule Z. If there is no supplier balance on the Allocatee's bill, the credit will remain on the distribution portion of the bill. If the customer received a bill with a distribution credit and a supplier debit, the company would transfer the credit to the supplier portion if requested by the customer.

Where can I find general information about my NSTAR Electric bill?
More information, including a sample of a typical NSTAR bill, is available by viewing NSTAR's “Understanding My Bill” page.

Is more information available about interconnecting my generation system, so I can participate in the net metering program?
Visit the "Interconnections" section of NSTAR's web site and fill out the appropriate application for your generation. The section also includes other useful interconnection information including standards and requirements for interconnection, the net-metering tariff and the interconnection service agreement.

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