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PSC 119 Interconnection Guidelines
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PSC 119 Guidelines for Interconnecting DG Systems under 20kW to the Utility Distribution System
The PSC 119 Guidelines explain the procedures and requirements set forth under the DG Interconnection Rules, and contain standard PSCW interconnection application forms and agreements. While the DG Interconnection Rules and Guidelines cover all DG systems up to 15 megawatts (MW) that operate in parallel with electric distribution systems, this fact sheet focuses on DG systems with a capacity of less than 20 kilowatts (kW).
Even though you may have only a few panels, your utility will regard this system as a "customer-sited distributed generation facility" if you apply for interconnection. For this reason, you should choose an installer who is both licensed and experienced with DG interconnections. You and your installer will need to work with your utility to be sure your system conforms to interconnection requirements for safety and reliability. PSC 119 standardizes these requirements across the state, making the process easier and less expensive for both installers and system owners.
Applicant Responsibilities
- Coordinating the design, installation, operation and maintenance of the system
- Making an application for interconnection through the local public utility
- Insuring that the distributed generation system conforms to all codes, standards, laws and regulations at the local, state and national level, and conforms to the requirements of the interconnection guidelines
- Acquiring and paying for all required permits, authorizations and licenses
The Interconnection Process
- Obtaining Information and Application Materials: When an applicant requests information about interconnecting a DG system to the utility grid, the local public utility is required to provide information and PSCW Standard Application materials within five business days.
- Completing and Submitting the Application: The applicant works with the system installer to complete the application, and submits it for review. The utility has ten business days to inform the applicant if the application is complete, or if it is incomplete and must be resubmitted. If resubmittal is required, necessary changes must be described. The applicant is not charged any fees for review of the application.
- Application Review and Notification: The utility reviews the submitted application and notifies the applicant within ten business days if the application is approved. If distribution system upgrades are required (e.g., a new meter) a cost estimate is provided to the applicant at this time, or the public utility notifies the applicant that an engineering review or distribution system study is required. If the application is not approved, it must be clearly documented so that the applicant can rectify the problem. (Using a UL approved inverter or paralleling equipment should significantly reduce the need for an engineering review.)
- If Additional Studies Are Required: In situations where an engineering review or distribution system study is required, the applicant has one year to request that the review or study be done. Once the request is received, the public utility must complete the review or study within ten business days. The applicant for a facility under 20 kW is not charged any fees for engineering or distribution system studies.
- If System Upgrades Are Required: If distribution system upgrades are required, the applicant has one year to decide whether to proceed with installation and commit to paying for the upgrades.
- Execution of the Agreement: Once the application is approved, all reviews and studies are completed, and the applicant has committed to paying for any distribution system upgrades, the DG Interconnection Agreement (PSC 6029) is executed between the public utility and the applicant.
- Installation and Notification: The applicant installs the small, distributed generation system as specified in the application materials. When installation is complete the applicant notifies the public utility.
- System Testing and Acceptance: The public utility has ten business days to test the installation and five business days to issue a formal letter of acceptance to the applicant. If the public utility does not test the installation within ten business days the system is considered accepted and may interconnect to the distribution system. If the public utility tests the system and the test is successful, a letter of acceptance must be provided to the applicant with five business days. If the system fails the public utility's testing, the applicant shall work with the utility to take corrective action.
System Insurance Requirements
- A minimum of $300,000 liability insurance or proof of financial responsibility is required for each interconnection
- The applicant is required to provide a certificate of insurance containing a minimum of 30 days notice if the liability insurance policy is dropped or liability coverage is decreased
- For small DG systems additional insurance requirements, such as requiring the system owner to include the public utility as a co-insured, are not allowed.
Design Requirements for the System
- The Rules clearly state the technical design requirements for interconnecting distributed generators in Wisconsin. The Guidelines include specifications for grounding, operating limits, protective functions, and circuit breakers.
- These design requirements are largely based on existing UL, ANSI and IEEE standards.
- Interconnection equipment (e.g., an inverter) listed by a nationally recognized certifying body as meeting the applicable testing requirements of UL 1741 shall be accepted for interconnection without additional protection systems. Certified interconnection equipment does not require additional testing by the public utility.
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