1. (1) A public utility must use the Tier 4 interconnection review procedures when an applicant submits an application requesting Tier 4 review to interconnect a small generator facility meeting the following requirements:

   1. (a) The small generator facility must have a nameplate rating of 10 megawatts or less.
   2. (b) An applicant whose Tier 1, Tier 2, or Tier 3 application was denied may request that the public utility treat that existing application already in the public utility’s possession as a new Tier 4 application. Within ten business days of receipt of the applicant’s request to use the existing application, the public utility will transfer the existing application to the Tier 4 process and notify the applicant whether or not the application is complete. If the application is incomplete, the public utility must provide a written list detailing all information that the applicant must provide to complete the application. The applicant will have ten business days after receipt of the list to submit the listed information. Otherwise, the application will be deemed withdrawn. The public utility must notify the applicant within ten business days of receipt of the revised application whether the revised application is complete or incomplete. The public utility may deem the application withdrawn if it remains incomplete.
2. (2) A public utility must approve an application to interconnect a small generator facility under the Tier 4 interconnection review procedures if the public utility determines that the safety and reliability of the public utility’s transmission or distribution system will not be compromised by interconnecting the small generator facility. The applicant must pay the reasonable costs of any interconnection facilities or system upgrades necessitated by the interconnection.
3. (3) In addition to the timelines and requirements in OAR 860-082-0025, the timelines and requirements in sections (5) through (12) of this rule apply to Tier 4 interconnection reviews.
4. (4) A public utility and an applicant may agree to waive the requirement for a scoping meeting, the system impact study, or the facilities study. The applicant may waive the requirement for a feasibility study.

5. (5) A public utility must schedule a scoping meeting within 10 business days after notifying an applicant that its application is complete.

   1. (a) The public utility and the applicant must bring to the scoping meeting all personnel, including system engineers, as may be reasonably required to accomplish the purpose of the meeting.
   2. (b) The public utility and applicant must discuss whether the public utility should perform a feasibility study or proceed directly to a system impact study, a facilities study, or an interconnection agreement.

   3. (c) If the public utility determines that no studies are necessary, then the public utility must follow the requirements in OAR 860-082-0025(7) if:

      1. (A) The application meets the criteria in section (2); and
      2. (B) The interconnection of the small generator facility does not require system upgrades or interconnection facilities different from or in addition to the applicant’s proposed interconnection equipment.
   4. (d) If the public utility determines that no studies are necessary and that the small generator facility could be interconnected safely if minor modifications to the transmission or distribution system were made (for example, changing meters, fuses, or relay settings), then the public utility must offer the applicant a good-faith, non-binding estimate of the costs of such proposed minor modifications. Modifications are not considered minor under this subsection if the total cost of the modifications exceeds $10,000. If the applicant authorizes the public utility to proceed with the minor modifications and agrees to pay the entire cost of the modifications, then the public utility must send the applicant an executed interconnection agreement within 15 business days of receipt of the applicant’s agreement to pay for the minor modifications.

6. (6) If the applicant requests a feasibility study, then the public utility must provide the applicant with an executable feasibility study agreement within five business days of the date of the scoping meeting.

   1. (a) The feasibility study agreement must include a detailed scope for the feasibility study, a reasonable schedule for completion of the study, and a good-faith, non-binding estimate of the costs to perform the study.
   2. (b) The feasibility study agreement must follow the standard form agreement developed by the public utility and approved by the Commission.
   3. (c) The applicant must execute the feasibility study agreement within 15 business days of receipt of the agreement or the application is deemed withdrawn.
   4. (d) The public utility must make reasonable, good-faith efforts to follow the schedule set forth in the feasibility study agreement for completion of the study.
   5. (e) The feasibility study must identify any potential adverse system impacts on the public utility’s transmission or distribution system or an affected system that may result from the interconnection of the small generator facility. In determining possible adverse system impacts, the public utility must consider the aggregated nameplate rating or export capacity when applicable of all generating facilities that, on the date the feasibility study begins, are directly interconnected to the public utility’s transmission or distribution system, have a pending completed application to interconnect with a higher queue position, or have an executed interconnection agreement with the public utility.
   6. (f) The public utility must evaluate multiple potential points of interconnection at the applicant’s request. The applicant must pay the costs of this additional evaluation.
   7. (g) The public utility must provide a copy of the feasibility study to the applicant within five business days of the study’s completion.
   8. (h) If the feasibility study identifies any potential adverse system impacts, then the public utility must perform a system impact study.

   9. (i) If the feasibility study does not identify any adverse system impacts, then the public utility must perform a facilities study if the public utility reasonably concludes that a facilities study is necessary to adequately evaluate the application.

      1. (A) If the public utility concludes that a facilities study is not required, then the public utility must approve the application if the application meets the criteria in section (2) and the interconnection of the small generator facility does not require system upgrades or interconnection facilities different from or in addition to the applicant’s proposed interconnection equipment.
      2. (B) If the public utility concludes that a facilities study is not required and that the small generator facility could be interconnected safely if minor modifications to the transmission or distribution system were made (for example, changing meters, fuses, or relay settings), then the public utility must offer the applicant a good-faith, non-binding estimate of the costs of such proposed minor modifications. Modifications are not considered minor under this paragraph if the total cost of the modifications exceeds $10,000. If the applicant authorizes the public utility to proceed with the minor modifications and agrees to pay the entire cost of the modifications, then the public utility must approve the application.

7. (7) If a public utility is required to perform a system impact study under subsection (6)(h), or if an applicant and a public utility agree in the scoping meeting to waive the feasibility study and proceed directly to the system impact study, then the public utility must provide the applicant with an executable system impact study agreement within five business days of completing the feasibility study or from the date of the scoping meeting, whichever is applicable.

   1. (a) The system impact study agreement must include a detailed scope for the system impact study, a reasonable schedule for completion of the study, and a good-faith, non-binding estimate of the costs to perform the study.
   2. (b) The system impact study agreement must follow the standard form agreement developed by the public utility and approved by the Commission.
   3. (c) Within 15 business days of receipt of the system impact study agreement the applicant must execute and return the system impact study agreement or submit a notice of intent to use a third-party consultant to conduct the system impact study, or the application is deemed withdrawn.
   4. (d) The public utility must make reasonable, good-faith efforts to follow the schedule set forth in the system impact study agreement for completion of the study.
   5. (e) The system impact study must identify and detail the impacts on the public utility’s transmission or distribution system or on an affected system that would result from the interconnection of the small generator facility if no modifications to the small generator facility or system upgrades were made. The system impact study must include evaluation of the adverse system impacts identified in the feasibility study and in the scoping meeting.
   6. (f) In determining possible adverse system impacts, the public utility must consider the aggregated nameplate rating, or export capacity when applicable, of all generating facilities that, on the date the system impact study begins, are directly interconnected to the public utility’s transmission or distribution system, have a pending completed application to interconnect with a higher queue position, or have an executed interconnection agreement with the public utility. If the small generator facility limits export pursuant to OAR 860-082-0033, the system impact study must use export capacity instead of the nameplate rating, except when assessing fault current contribution. To assess fault current contribution, the system impact study must use the rated fault current if the customer provides the relevant information or provide a written explanation for cases where the utility does not want to rely on customer-provided data. An example of customer-provided data would include provision of manufacturer test data (pursuant to the fault current test described in IEEE 1547.1-2020 clause 5.18) showing that the fault current is independent of the nameplate rating. The public utility must provide an explanation for any cases where the utility does not want to rely on customer-provided data.

   7. (g) The system impact study must include:

      1. (A) A short circuit analysis;
      2. (B) A stability analysis;
      3. (C) A power flow analysis;
      4. (D) Voltage drop and flicker studies;
      5. (E) Protection and set point coordination studies;
      6. (F) Grounding reviews;
      7. (G) The underlying assumptions of the study;
      8. (H) The results of the analyses; and
      9. (I) Any potential impediments to providing the requested interconnection service.
   8. (h) If an applicant provides an independent system impact study to the public utility, then the public utility must evaluate and address any alternative findings from that study.
   9. (i) The public utility must provide a copy of the system impact study to the applicant within five business days of completing the study.
   10. (j) If a public utility determines in a system impact study that interconnection facilities or system upgrades are necessary to safely interconnect a small generator facility, then the public utility must perform a facilities study.
   11. (k) If the public utility determines that no interconnection facilities or system upgrades are required, and the public utility concludes that the application meets the criteria in section (2), then the public utility must approve the application with 15 business days of completion of the system impact study.
   12. (l) If the public utility determines that no interconnection facilities or system upgrades are required and that the small generator facility could be interconnected safely if minor modifications to the transmission or distribution system were made (for example, changing meters, fuses, or relay settings), then the public utility must offer the applicant a good-faith, non-binding estimate of the costs of such proposed minor modifications. Modifications are not considered minor under this subsection if the total cost of the modifications exceeds $10,000. If the applicant authorizes the public utility to proceed with the minor modifications and agrees to pay the entire cost of the modifications, then the public utility must approve the application within 15 business days of the applicant’s agreement to pay for the minor modifications.

   13. (m) StartFragment The public utility must allow opportunity for an applicant in any serially studied small generator interconnection queue to use a third-party consultant to conduct the system-impact study.

       1. (A) The public utility must publish criteria for applicants electing to use a third-party system impact study including minimum requirements for the study format and methods, the data sharing process, any non-disclosure and data handling agreements, and other needed policies. The criteria must also include:

          1. (i) A description of necessary analysis, as well as required format for output, including any necessary workpapers,
          2. (ii) A listing of national standards relied on by the public utility, and
          3. (iii) A listing of any additional critical standards required, with underlying rationale.
       2. (B) Each public utility must designate and make available a liaison for applicants electing to use a third-party consultant to clarify data, resolve ambiguities, and explain technical requirements to the best of the liaison’s ability. Information provided by the liaison will not replace or limit the utility’s review of the third-party consultant’s study under subsection (7)(o).

       3. (C) Each public utility must establish detailed instructions for eligible interconnection applicants StartFragment to:

          1. (i) Provide a qualifying notice of intent to use a third-party consultant to conduct the system impact study, including any forms required for non-disclosure and data handling agreements; and
          2. (ii) Request the data necessary to perform to the third-party system impact study to the utility’s specifications.
       4. (D) Within five (5) business days of receipt of an applicant’s notice of intent to use a third-party consultant to perform the system interconnection study, the public utility will notify the applicant in writing whether or not the application is complete.
       5. (E) The public utility must provide a third-party consultant access to public utility data within 21 calendar days of the public utility’s receipt of a qualifying notice of intent to use a third-party consultant to conduct a system impact study. Data provided by the public utility must be provided in a standardized, machine-readable format, except as otherwise agreed.EndFragment EndFragment

   14. StartFragment (n) Applicant obligations for third-party studies.

       1. (A) Before submitting a third-party study, the applicant must notify the public utility of their intent to use a third-party consultant for the system impact study in the manner set forth by the public utility under subsection (7)(m)(C).

       2. (B) Any third-party system impact study must be completed within 45 business days of the later of the following, unless another date is mutually agreed to:

          1. (i) The public utility’s written acceptance of applicant’s notice of intent to use a third-party consultant to perform system impact study, or
          2. (ii) The applicant’s receipt of data required under this rule.
       3. (C) Any third-party study must include a professional engineer’s stamp.EndFragment

   15. StartFragment (o) The public utility must accept or reject in writing any third-party study within 30 business days of study receipt.

       1. (A) If a third-party study is accepted, the public utility must follow the process set forth in subsection (7)(j), (k), or (l).
       2. (B) If a study is rejected, the public utility must identify all study modifications required, with supporting rationale.
       3. (C) If a study is rejected, the applicant has 45 business days to provide an updated study addressing all public utility-raised issues.
       4. (D) A public utility’s decision to approve or reject a third-party study must be based on safety, reliability and compliance with published standards.
       5. (E) The public utility may charge the applicant for the reasonable costs incurred by the public utility in preparing and providing technical data under this subsection.
       6. (F) The public utility may charge the applicant for the reasonable costs of reviewing any third-party study up to $1,000.

8. (8) If a public utility is required to perform a facilities study under subsection (6)(i) or 7(j), or if an applicant and a public utility agree in the scoping meeting to waive the system impact study and proceed directly to the facilities study, then the public utility must provide the applicant with an executable facilities study agreement within five business days of completing the system impact study or within five business days from the date of the scoping meeting, whichever is applicable.

   1. (a) The facilities study agreement must include a detailed scope for the facilities study, a reasonable schedule for completion of the study, and a good-faith, non-binding estimate of the costs to perform the study.
   2. (b) The facilities study agreement must follow the standard form agreement developed by the public utility and approved by the Commission.
   3. (c) The applicant must execute the interconnection facilities study agreement within 15 business days after receipt of the agreement or the application is deemed withdrawn.
   4. (d) The public utility must make reasonable, good-faith efforts to follow the schedule set forth in the facilities study agreement for completion of the study.
   5. (e) The facilities study must identify the interconnection facilities and system upgrades required to safely interconnect the small generator facility and must determine the costs for the facilities and upgrades, including equipment, engineering, procurement, and construction costs. Design for any required interconnection facilities or system upgrades must be performed under the facilities study agreement. The public utility must also identify the electrical switching configuration of the equipment, including transformer, switchgear, meters, and other station equipment.
   6. (f) The public utility may contract with a third-party consultant to complete the interconnection facilities and system upgrades identified in the facilities study. A public utility and an applicant may agree in writing to allow the applicant to hire a third-party consultant to complete the interconnection facilities and system upgrades, subject to public utility oversight and approval.
   7. (g) The interconnection facilities study must include a detailed estimate of the time required to procure, construct, and install the required interconnection facilities and system upgrades.
   8. (h) If the applicant agrees to pay for the interconnection facilities and system upgrades identified in the facilities study, then the public utility must approve the application.
9. (9) The public utility may contract with a third-party consultant to complete a feasibility study, system impact study, or facilities study. A public utility and an applicant may agree in writing to allow the applicant to hire a third-party consultant to complete a feasibility study, system impact study, or facilities study, subject to public utility oversight and approval.

10. (10) The interconnection process is not complete until:

    1. (a) The public utility approves the application;
    2. (b) Any interconnection facilities or system upgrades have been completed;
    3. (c) Any minor modifications to the public utility’s transmission or distribution system required under subsections (5)(d), 6(i)(B), or (7)(l) have been completed;
    4. (d) The witness test, if conducted by the public utility, is successful; and
    5. (e) The applicant and public utility execute a certificate of completion.
11. (11) If a small generator facility is not approved under the Tier 4 interconnection review procedures, then the public utility must provide a written explanation of the denial to the applicant.

12. StartFragment (12) Interconnection Study Timelines.

    1. (a) Notwithstanding other subsections in this rule regarding timing of studies, the following timelines are applicable to serially studied small generators.

       1. (A) The public utility must perform a system impact study within 45 business days of the latest of the following:

          1. (i) The public utility’s receipt of a signed system impact study agreement from the applicant;
          2. (ii) The public utility’s receipt of all necessary study fees and deposits from the applicant; and
          3. (iii) The public utility’s receipt of all necessary data from applicant.

       2. (B) The public utility must perform a facilities study within 45 business days of the latest of the following

          1. (i) The public utility’s receipt of a signed facilities study agreement from the applicant;
          2. (ii) The public utility’s receipt of all necessary study fees and deposits from the applicant; and
          3. (iii) The public utility’s receipt of all necessary data from the applicant.

    2. (b) For any study that is not provided in the timeline specified in subsection (12)(a)(A) or (B), the public utility:

       1. (A) Must reduce the study costs owed to the public utility from the applicant by fifty percent for any delay up to 15 business days from the due date for the study, and by 100 percent for any delay longer than 15 business days, refund any study costs in excess of the reduced study fees if the applicant has already remitted payment to public utility, and file a report with the Commission indicating the reason for failure to meet the time requirement and the amount of time required to complete the study; or
       2. (B) May seek a waiver from the Commission of the obligation to finish the study within 45 days, for good cause.

13. (13) Construction timelines.

    1. (a) This subsection applies to all serially studied small generators proposing to interconnect to a public utility’s system.

    2. (b) At the time of executing the interconnection agreement, the public utility must commit to a construction timeline, which means from interconnection agreement execution to witness test, no longer than 600 calendar days. If the public utility cannot commit to a construction timeline of 600 calendar days or less, the public utility must either:

       1. (A) Execute an agreement with applicant under which applicant will assume responsibility for design, procurement, and construction of mutually agreed-upon interconnection facilities and stand-alone system upgrades, to be consistent with Commission-approved terms and conditions for the option to build in the QF-LGIA (see Order No. 25-355);
       2. (B) Seek a waiver of the maximum 600-day construction timeline from the Commission for good cause; or
       3. (C) Execute an Interconnection Agreement in which the applicant agrees to a construction timeline that exceeds 600 days.

    3. (c) A public utility that fails to construct the facilities specified in the Interconnection Agreement within the 600-day maximum timeline, or date specified in the Interconnection Agreement if later, will discount the costs charged to the applicant for interconnection, including costs of facilities by five (5) percent for every 30 calendar days construction extends beyond the maximum 600-day timeline or agreed upon end of construction timelines, if later than 600 days, unless:

       1. (A) The public utility seeks a waiver from the Commission of the obligation to construct facilities within the maximum 600-day timeline, or by the date specified in the Interconnection Agreement if later, for good cause, which could include the applicant’s failure to meet a milestone or payment set forth in the interconnection agreement.
       2. (B) The public utility and applicant agree in writing to extend the construction timeline included in the Interconnection Agreement.
14. (14) Other Interconnection Options; Limited Operation. If any of applicant’s interconnection facilities or system upgrades are not reasonably expected to be completed by the end of the construction timeline specified in the Interconnection Agreement, the public utility shall, upon the request and at the expense of Applicant, perform operating studies on a timely basis to determine the extent to which the applicant’s interconnection facilities may operate prior to the completion of system upgrades consistent with applicable laws and regulations and reliability standards. A public utility shall allow applicant to operate its generating facility and interconnection facilities in accordance with the results of such studies. The costs the public utility incurs under this subsection are not subject to discount as provided in subsection 13(c).
    EndFragment

Statutory/Other Authority

ORS 183, ORS 756 & ORS 757

Statutes/Other Implemented

ORS 756.040 & ORS 756.060

History

PUC 4-2026, temporary amend filed 04/01/2026, effective 04/01/2026 through 09/04/2026
PUC 4-2024, amend filed 04/09/2024, effective 04/09/2024
PUC 10-2009, f. & cert. ef. 8-26-09