Net Energy Metering (or NEM) is one way to lessen Hawaii’s dependence on imported oil by encouraging the greater use of eligible renewable energy sources like solar (photovoltaic), wind, biomass, or hydroelectric power for electrical generation by residential and commercial customers. Hawaiian Electric Company, Maui Electric Company, and Hawaii Electric Light Company support Net Energy Metering and recognize their roles to help Hawaii transition from fossil fuels to more renewable energy resources. Here is some general information that we hope will be helpful. For routinely updated information regarding circuit penetration and new MECO procedures, please see our Important Updatessection.
1. What is net energy metering?
According to Hawaii state law (Hawaii Revised Statues (HRS) Section 269-101 - 269-111), all residential and commercial utility customers who own and operate an eligible renewable energy generation system up to a generating capacity of 100 kW and intend to connect to utility grid, must register their systems with their utility by executing a NEM agreement. The executed agreement allows the NEM customer to connect their renewable generator to the utility grid, allowing it to export surplus electricity into the grid, and to receive credits at full retail value which can be used to offset electricity purchases over a 12-month period.
NEM customers are billed for net energy purchased, which is determined by subtracting the excess energy exported to the utility grid from the total energy supplied by the utility. Here is the formula:
Energy Supplied by the utility (kWh)
- Excess Energy exported to the utility (kWh)
= Net Energy Billed to the Customer (kWh)
2. What is the value of NEM?
NEM allows you to offset all or part of your electricity purchases from the utility by energy produced by your eligible renewable generation system and export any excess electricity to the utility grid at the retail rate.
NEM gives value to the excess electricity you produce with your renewable generation system. Electricity generated by your renewable generator would first supply power for your own needs and any additional power you need would be purchased from the utility. When a NEM customer generates more electricity than what is consumed, excess energy produced can be exported back to the utility at full retail value which can be used to offset electricity purchases over a 12-month period.
This is in contrast to other non-NEM customers with renewable energy generation systems. If they have a power purchase agreement, they are compensated for power exported to the utility grid at a lower wholesale rate. Standard interconnection customers must consume all electricity that is self-generated, and not allow to export surplus energy to the grid nor be compensated. With NEM, you are in effect being given the retail credit for excess power which you generate.
3. What types of generators are eligible?
Hawaii law specifies that NEM applies to solar, wind, biomass or hydroelectric generation facilities, or a hybrid system of two or more of these technologies, with a capacity up to 100 kW. (For more information about these technologies, visit the websiteof the State of Hawaii, Department of Business, Economic Development and Tourism, Strategic Industries Division, Energy Branch).
The Hawaii Public Utilities Commission (PUC), by rule or order, can change the maximum allowable capacity.
4. I am installing a solar water-heating system. Does that qualify for net energy metering?
No. NEM applies only to systems that generate electricity. Solar electric systems, known as photovoltaic (PV), use solar cells to convert the sun’s light into electricity. By contrast, solar water-heating systems use heat from the sun directly to heat water for your use. Since solar water-heating systems do not produce electricity, they cannot feed into the grid and do not qualify for NEM.
New and existing NEM systems will require a new bi-directional meter capable of measuring the energy supplied by your utility and the excess electricity from your renewable energy generation system exported to the grid. The utility will provide the meter at no cost to you when the NEM agreement is executed.
6. What happens to my electric bill if I generate more electricity than I use from the utility?
The NEM agreement allows the customer to carry over unused credits (excess net generation expressed as a monetary value) to future bills within a 12 month period, starting from when the agreement is executed. Any unused credits remaining at the end of each 12- month reconciliation period may not be carried over to the next 12-month period.
A required minimum charge is assessed in your monthly electric bill to cover fixed costs like reading your meter and billing. This minimum charge is due and payable each month even if you generate more electricity than you use from the utility.
Links to maps showing highly penetrated circuits can be found here.
To request a Circuit Penetration Inquiry in order to determine the available kilowatts available for potential distributed generation systems, email the following information to: cpi@mauielectric.com
• Tax Map Key (TMK) number of property where the system is being proposed
• Address of property where the system is being proposed
Please send only one request per email and allow 3-5 business days for the results. Information provided is based on data available on the date your response is sent, and is for general information purposes only. If you wish to proceed, you must submit the documents below and receive written approval from MECO that your application has been approved.
8. What is the potential interconnection application timeline for an NEM project?
The following table illustrates the estimated timeline for the NEM process from beginning to end:
Complete Appendix I with customer information including the customer's name, address, electric account number, and contact information. The agreement must be signed by both the customer and the licensed contractor who will complete the work. The make, model and number of renewable generator (PV modules, wind turbine, hydroelectric generator, or biomass generator) and inverter information must also be provided.
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Submit a single line drawing accurately illustrating how power output from the renewable energy generator is to be interconnected to the utility. A sample single line drawing can be downloaded here.
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Module specification sheets from the equipment manufacturer.
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Inverter specification sheets from the equipment manufacturer.
Complete Exhibit A of Appendix II with customer information including the customer's name, address, electric account number, and contact information provided. The agreement must be signed by the customer. The insurance company used for insuring the system must be noted. The make, model, and number of renewable generator (PV modules, wind turbine, hydroelectric generator, or biomass generator) and inverter information must also be provided. Information about the installer must be complete.
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For systems greater than 10 kW and less than 30 kW, submit a single line drawing accurately illustrating how the system is to be interconnected to the utility along with the relay list, trip, and settings of the generating facility.
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For systems greater than 30 kW but not more than 100 kW, submit a three line drawing accurately illustrating how the system is to be interconnected to the utility with a licensed professional electrical engineer stamp along with the relay list, trip, and settings of the generating facility.
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Module specifications sheets from the equipment manufacturer.
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Inverter specification sheets from the equipment manufacturer.
If your renewable energy generation system mistakenly back-feeds power into an electric line that utility crews think is de-energized, the crews can be seriously injured or even killed. The interconnection study also helps assure the utility that you and other customers continue to receive reliable service and good power quality, avoiding potentially disruptive swings in voltage levels that could damage your equipment and that of the utilities.
Whether you are installing a new renewable energy generation system or considering NEM for an existing renewable energy generation system, compliance with all safety and other codes are required.
The 2005 Legislature, by Act 104, gave the Hawaii Public Utilities Commission authority to set requirements and limits as well as safety, performance, and reliability standards for NEM by order, tariff, or rule.
Net Energy Metering is intended to offset part or all of a customer's electric consumption from the Utility. During sunny days with low household consumption a customer's PV system may generate more electricity than used by the customer. Under these conditions the excess will flow back through the Utility meter to the grid. On other days a customer's PV system may not generate enough electricity to completely power the customer's load. In this case some electricity will flow from the grid through the Utility meter to supply the remaining power for the customer. Only the electricity flowing to and from the grid is measured by the Utility meter. The Utility meter will not measure the electricity generated by the customer's PV system to the customer's load. The Utility meter will only measure the excess electricity going back to the grid or the extra power supplied from the grid. Therefore, the energy measured by the Utility meter will not match the energy measured by the PV inverters. See PV system diagram below.
