NOTE: The current version of this document is a draft for review and evaluation and is subject to change. Users of this document are encouraged to return to this page regularly to determine if a revision has been posted.

California Electric Rule 21 Supplemental Review Guideline Revised August 2005 Developed by the California Energy Commission Rule 21 Working Group (Acrobat PDF file, 60 pages, 428 kilobytes) online August 31, 2005.

The California Rule 21 Supplemental Guideline is intended to support the standardized implementation of interconnection requirements defined in California Electric Rule 21. Please note that the Guideline is not a publication formally adopted by the California Public Utilities Commission, the California Energy Commission, the state of California, or any of the utilities subject to Rule 21. Rather, it is designed to be an informational document prepared by the Rule 21 Interconnection Working Group that could be used in the evaluation of an interconnection request.

In particular, this Supplemental Review Guideline addresses generating facility Interconnection Applications that have failed one or more of the Rule 21 Initial Review Process screens and are undergoing Supplemental Review.

For the utility engineer, the Supplemental Review Guideline provides basis for performing the Supplemental Review in a manner consistent with other engineers and other utilities, and for focusing their efforts on what are generally agreed to be the primary issues of concern. For the generating facility applicant, the Supplemental Review Guideline can act as a primer on the topics addressed by the Initial Review Process, as a guide to possible solutions when Initial Review Process failure is anticipated, and as a basis for understanding the utility's decision as a result of a Supplemental Review.

The Initial Review Process was designed as a first order utility system impact study and is designed to approve systems that should have no impact on the distribution system to which they are to be connected. Supplemental Review is intended to provide a slightly more detailed review of the conditions that caused the system to fail the Initial Review Process and determine if:

• no additional requirements are necessary to allow interconnection;

• some additional requirements or changes (to the GF, the utility distribution system, or both) are necessary to allow interconnection; or

• a more detailed system impact study is necessary (the cost and schedule for the study are also provided).

While the defined steps in the Initial Review Process may be performed by an individual with only a cursory understanding of the distribution system, a qualified utility engineer will perform the Supplemental Review. Supplemental Review allows the engineer the opportunity to evaluate the proposed generating facility at its intended location.

Beyond the screening process in each major issue, this Supplemental Review Guideline does not provide specific steps or methods of evaluating the proposed GF, thus leaving latitude in its interpretation. However, by defining the issues that are to be considered for each Initial Review Process screen failure and general ways of dealing with those issues, it is expected that the Supplemental Review Guideline will promote a consistent implementation of Rule 21 requirements in those utilities that adopt them.