FERC Order 845 (2018) — Reform of Generator Interconnection Procedures and Agreements

Order No. 845, issued in April 2018 in Docket RM17-8-000, reformed the large generator interconnection procedures to better accommodate the evolving resource mix, particularly variable energy resources like wind and solar. By 2018, interconnection queues were increasingly dominated by renewable and hybrid projects, yet LGIP rules from Order 2003 had not fully addressed repowering, co-located storage, and surplus capacity at existing points of interconnection.

A key innovation was surplus interconnection service, which allows generators to use spare capacity at an existing interconnection point without triggering a full new interconnection study. For example, a wind farm operating below its approved capacity could add a co-located battery within unused headroom, reducing cost and timeline compared to a greenfield interconnection request. FERC established eligibility criteria, study requirements, and tariff provisions governing how surplus service is requested and granted.

The order required transmission providers to post more interconnection-related information publicly, improving transparency for developers evaluating queue positions and upgrade costs. Order 845 also updated study processes to reflect modern grid conditions, including revised modeling assumptions for variable resources and clearer rules for processing modifications to existing interconnection agreements. These reforms modernized the interconnection framework as the power system transitioned toward a cleaner resource mix.

Order 845-A addressed rehearing requests and clarified surplus service provisions. While Order 2023 later overhauled queue administration with cluster studies, Order 845's surplus interconnection and transparency reforms remain important for developers expanding or repowering at existing sites. The order built directly on Order 2003's LGIP/LGIA foundation.

Order 845 revised how transmission providers evaluate requests to increase generating facility capacity, add energy storage, or change technology at existing sites, reducing barriers to repowering aging wind turbines with modern equipment. The order strengthened affected system study coordination and required more detailed queue data posting so developers could assess restudy risk before committing capital. FERC found that incremental reforms were necessary before broader queue overhauls because renewable repowering and hybrid projects were stalling on procedural uncertainty even when physical interconnection headroom existed at the point of interconnection.

Order 845 required transmission providers to process interconnection-related data requests more consistently and to explain study methodologies used for variable resources. These transparency measures foreshadowed the deeper queue reforms in Order 2023 while delivering immediate benefits to developers expanding operating projects. Surplus service provisions remain widely used for co-located storage and repowering at existing renewable sites. The reforms reduced study burdens for incremental additions that did not require new POIs.