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net energy billing/chapter 315 small generator aggregation

Net Energy Billing
What is net energy billing?
Under the Maine Public Utilities Commission’s Chapter 313 statute CMP is required to enter into a Customer Net Energy Billing Agreement with any customer seeking to connect a generator operating in parallel with CMP, provided the generator is an “eligible facility” (see below) and is less than 660 kW in size (total installed capacity). With “net energy billing,” the utility invoices the customer based on net energy over the billing period, taking into account any accumulated kilowatt-hour credits from prior billing periods. “Net energy” is the difference between the energy used by the customer and the energy generated by the customer’s facility over a common billing period. If the monthly net metered amount indicates generator output in excess of monthly usage, a customer will still be responsible to pay CMP’s minimum delivery charge. The unused kWh credits go into a “bank” administered by CMP. The banked kWh credits will be netted against usage in future monthly bills with the oldest credits applied first. Each unused kWh credit may remain in the bank for up to one year. At the end of each month, CMP will deduct from the bank any unused kWh credits that have reached their 12-month expiration.
Who is eligible for net energy billing?
Net energy billing is available to customers who use energy generated with renewable fuel or technology as specified in 35-A M.R.S.A. §3210(2)(C). This includes:
• Fuel cells;
• Tidal power;
• Solar, wind, and geothermal installations;
• Hydroelectric;
• Biomass; and
• Generators fueled by municipal solid waste in conjunction with recycling.
• Micro-Combined Heat and Power System. “Micro-Combined Heat and Power System” means a system that:
• Produces heat and electricity from one fuel input, without restriction to specific fuel or generating technology;
• Has an electric generating capacity rating of at least one kilowatt and not more than 30 kilowatts and a fuel system efficiency of not less than 80% in the production of heat and electricity or has an electric generating capacity of at least 31 kilowatts and not more than 660 kilowatts and a fuel system efficiency of not less than 65% in the production of heat and electricity;
• May work in combination with supplemental or parallel conventional heating systems;
• Is manufactured, installed and operated in accordance with applicable government and industry standards; and
• Is connected to the electric grid and operated in conjunction with the facilities of a transmission and distribution utility.
The generating facility must:
• Have an installed capacity of 660 kW or less to serve its own electricity requirements,
• Be located within the utility’s service territory
• Be located on or near the customer’s premises, and
• Be used primarily to offset part or all of the customer’s own electricity needs.
How does net energy billing work?
If the electricity generated exceeds the customer’s kilowatt-hour usage any net excess is banked and applied to the customer’s future bills as a reduction in usage. Within a current billing cycle the amount of generation produced would offset the amount purchased from a supplier and would reduce the customer’s delivery charge if the customer’s usage is greater than 50 kWhs.
If a customer is on a TOU rate the generation recorded on the out meter will be applied first to like time periods (e.g. on-peak will be applied against on-peak first, shoulder against shoulder, etc.). If there remains excess generation in any time period beyond the usage in the same period the excess will be used in the next closest time period. The intent is to use all generation produced within that billing cycle before adding any to the bank. If generation exists even after reducing all usage to zero (0) within the billing cycle the excess will be banked in whichever time period it was produced. In the subsequent month(s) energy will be drawn from the bank in the manner described in the preceding sentences.
If the customer’s usage exceeds the electricity generated plus any banked credits, the customer is billed for the excess usage at the applicable retail rate for electricity service. The customer’s invoice will reflect how many kWhs were credited against the current cycle’s usage.
Chapter 313 allows customers or shared ownership customers to designate up to 10 accounts for net energy billing under a single contract. The primary or facility account has to be one of the 10 accounts. The customer must designate a specific percentage allocation for the primary and each secondary account. The secondary accounts need to be in the same name as the primary account and the percent allocation has to sum to 100%. The customer may contact CMP no more frequently than every 3 months to reallocate the outflow distribution from their system. It is assumed that primary accounts in contracts without secondary accounts will be allocated 100% of the excess energy produced.
A customer may accumulate unused credits and apply them against usage over the next 12 billing periods on a first-in, first-out basis. If the unused credits are not used within 12 billing months, the unused credits from the oldest month would be lost. The customer receives no compensation for eliminated unused credits. If a customer has multiple accounts associated with their net energy billing agreement the net out energy produced at the primary account will be allocated to each account (both primary and secondary accounts) based upon the predetermined percentages. If at the end of each billing period any account (primary or secondary) still has excess associated with it, a bank will be created specific to that individual account, Energy associated with each account will be billed and banked separately. As stated above, if banked energy associated with any designated accounts remains for 12 billing periods, energy associated with that bank will be lost.

Net energy billing applies only to kilowatt-hour usage charges. Net energy billing customers are responsible for all other charges applicable to the customer’s rate class (for example, a monthly service charge, demand charges, etc) and recovered either through fixed amounts or over units other than kWh.
A customer who uses net energy billing may purchase generation service from any competitive electricity provider that agrees to provide service on a net energy basis. If the customer is served through the standard offer, the standard offer provider shall provide service on a net energy basis.
The utility may install additional meters to record generation and usage separately, provided that the customer signing a net energy billing agreement will not be charged for those additional meters or other equipment. CMP determines how it will meter each account based upon the size of the generator and the expected monthly usage. If monthly usage is expected to always exceed the generated output, CMP will replace the current meter with a single net “smart” meter. This meter can operate in both directions depending on the relationship between the generator output and usage at any point in time, and it provides a true net reading at the end of the monthly billing cycle.

If the generator output is likely to exceed electric usage during some months, CMP will install either a meter adapter with two “smart” meters or a single “alpha” meter. The meter adapter with two meters (each meter will only move in the forward direction) may be used if the service size is 200 amps or less. One meter will only record the net outflow of energy delivered from the premise to the CMP system and the other meter will only record the net inflow of energy from CMP’s system. In some cases, a single solid-state net energy meter may be used (currently available for single-phase (non-demand) 200 amp and 320 amp only). This alpha meter will record the net flow of energy in both directions with a single meter. As a general rule, alpha meters are only used for small commercial net energy customers.
Prior to operating a generator in parallel with CMP’s system, a customer must submit an application for an Interconnection Agreement with CMP. The application may be found under Small Generator Interconnection Procedures on the CMP Home page at If the generator passes the technical screening as defined in the Maine Public Utilities Commission Chapter 324 statute, then both the Interconnection Agreement and the CNEBA will be sent to the customer for signature.
The following link provides additional information concerning MPUC Chapter 313.
A customer may also be required to schedule an on-site inspection if the system is atypical. Should period testing of the automatic protective devices be required on a biennial or less frequent basis, the customer shall allow CMP to witness the test or to access the test reports or logs.
Here is a link to see a sample Residential 12-month net energy billing contract:
Chapter 313 Sample CNEBA.pdf Sample_Rolling 12 month_Residential_CNEBA.PDF

Here is a link to our customer net energy billing agreement (CNEBA) procedures:



Chapter 315 Small Generator Aggregation


The purpose of Chapter 315, Small Generator Aggregation, is to provide small generators access to the ISO New England (ISO-NE) wholesale energy market. Generators who sign a Chapter 315 agreement will receive an energy payment for any excess generation based upon regional wholesale locational prices. Under Maine Public Utilities Commission Chapter 315, Central Maine Power Company (CMP) is responsible for the administration of the sale of power from the seller’s facility to the Standard Offer Provider. Customers seeking to sell energy are required to sign a Small Generator Aggregation Agreement and an Interconnection Agreement before commencing service under Chapter 315.  A copy of Chapter 315 may be obtained at the following web site:


Chapter 315 Frequently Asked Questions

Chapter 315 Sample Agreement


If you are interested in signing a CNEBA with CMP, please call  Mike Erskine at 207-621-7887 or  Diana Morgan at 207-626-9736.