Utility Interconnection & Cogeneration
Many utility companies have specific guidelines in place for homeowners wishing to sell alternative energy back to the utility company. Even companies that do not have their own regulations in place must comply with the Public Utility Regulatory Policies Act (PURPA) of 1978, which requires utility companies to buy power back from "Qualifying Facilities" at an "avoided rate." Each electric company's avoided rate is equal to their cost of producing the power in their own power plants or buying the electricity from a large generation facility.
The avoided rate for power is usually much less per kWH than the price the homeowner pays for the utility power they use. These utilities reason that since they are still providing and maintaining power lines and distribution systems, the homeowner is only saving them the cost of actual power production, so the cost of actual production is all the homeowner is reimbursed for.
Some utilities will pay the same amount per kWH sold to them as they charge customers per kWH, known as "net metering." Under net metering, if you produce 500kWH of power in month and you use 800kWH of utility power in the same month, you would only pay for 300kWH on your utility bill. These utilities generally supply power meters that run backwards when the homeowner's system is feeding power into the grid and run forwards when the homeowner is using utility power, so the meter itself keeps track of the net balance of power used.
Below you will find links to summaries of home power system interconnection guidelines for various utilitiy companies in Alaska. If your utility provider is not listed, it is either because we have not yet obtained their interconnection requirements from them, or because they have no official requirements available.
- Links to Federal Regulations
- Alaska Electric Light & Power (AELP)
- Chugach Electric
- City of Sitka
- Golden Valley Electric Assoc. (GVEA)
- How to Obtain Qualifying Status For Your Facility (FERC)
- Public Utilities Regulatory Policy Act (PURPA) Table of Contents
- PURPA Cogeneration & Small Power Production Section
AELP requires the following basic technical requirements be met before a Qualifying Facility can interconnect with their system:
- The facility must conform to the National Electrical Code (NEC) as adopted in Alaska Statutes (AS) 18.60.580
- The system must also have a locking manual disconnect switch, allowing it to be positively isolated from GVEA's system when necessary, which can be switched under full load and padlocked open. The disconnect must be clearly labeled and accessable to utility personnel.
- The facility must have adequate overcurrent protection according to AELP's standards. If the overcurrent protection is tripped, the facility cannot reconnect without contacting AELP unless they have prior written authorization. Trace intertie capable inverters include built-in overcurrent protection. Contact AELP to determine if this is sufficient to meet their requirements.
- AELP will also provide their own overcurrent protection, in accordance with their current practices.
As of November 1, 2000, AELP will pay approximately 11 cents per kilowatt-hour for sellback power only when they are using diesel generation to meet customer power demands. If their standard hydroelectric power sources are capable of meeting customer power demands, they will not pay for surplus power generated by small home power facilities.
As with any plan to interconnect a home power system with the local utility company, you should contact AELP to arrange any necessary inspections before bringing the power system "on-line."
CLICK HERE to view the official text of AELP's Small Power Producers regulations.
Chugach Electric has produced a very comprehensive 86 page guide to their Interconnection Requirements for Non-Utility Generation. We can't effectively summarize the document on this page, so please contact Chugach Electric to request a full copy of their publication by mail.
James B. Wilson, Manager
Standards & Engineering Support
Chugach Electric Association, Inc.
PO Box 196300, Anchorage, AK 99519-6300
phone: 907-563-7494 fax: 907-562-0027
The City of Sitka has not written their own specific requirements. They follow the directives of the Public Utility Regulatory Policies Act (PURPA) of 1978, which requires utilities to buy electric power from private Qualifying Facilities (QF) at an Avoided Cost rate.
To become a Qualifying Facility, the independent power supplier has to produce electricity with a specified fuel type (cogeneration or renewables), and meet certain ownership, size, and efficiency criteria established by the Federal Energy Regulatory Commission (FERC).
GVEA has specific technical regulations in place for utility-intertie home power systems. Renewable energy supplied by the homeowner will be routed through a second meter, so the home's grid power usage is tracked on one meter and renewable "sellback" power is tracked on a separate meter. Power sold back to GVEA is paid for at GVEA's current "avoided" rate per kWH. As of October 2000, the avioded rate on GVEA power was approximately 2.5 cents per kWH.
Any renewable energy system producing 10kW of power or less must comply with GVEA's Parallel Interconnection Technical Requirements. Some of the hardware requirements can be met by purchasing a Trace SW series inverter, or a PS series inverter with the SWRC control unit (allowing necessary adjustments to be made to the PS inverter's factory settings). For instance:
- GVEA requires intertied home power systems to include "a system for automatically isolating the Facility from GVEA's system." Trace PS and SW series inverters include built-in "islanding" protection, preventing them from attempting to feed power to the grid in the event of a power outage. When grid power fails, the SW or PS inverter automatically stops feeding power into the utility grid lines.
- GVEA also requires that "the Facility shall be operated so that variations from acceptable voltage levels and other service impairing disturbances do not occur." Trace PS & SW series inverters produce utility quality 60Hz true sine-wave power. Their built-in protection circuitry provides over- and under-current protection, and the inverter automatically syncs its power output to match available AC grid power.
The system must also have a locking manual disconnect switch, allowing it to be positively isolated from GVEA's system when necessary. In some cases, the home power system may also need to be connected through a separate distribution transformer. GVEA will determine whether or not the transformer is necessary when they review the plans for the power system.
INSPECTION AND APPROVAL
In addition to hardware disconnect and safety requirements, GVEA must review the plans and specifications for the power system before it is installed. They will provide written notice of any modifications to the plans they find necessary. After required modifications are made, the final system plans must be re-submitted to GVEA for final approval. After plans are approved, the installed power system must have a final physical inspection before grid interconnection can be approved.
OPERATION, MAINTENANCE AND CONTROL
The homeowner is responsible for obtaining any necessary permits for the power system before it is put into operation. Once the system is fully operational, the homeowner must perform and keep records of all required system maintenance and testing, and allow GVEA to review the maintenance records and test results upon request.
GVEA has the right to disconnect the home power system from the power grid if they find it necessary. GVEA will consult with the homeowner before doing so in most cases, but if they determine the system must be disconnected immediately and/or the homeowner cannot be reached, GVEA will disconnect the home system without giving notice.
CLICK HERE to view the official text of GVEA's Parallel Interconnection Technical Requirements