Defines "surplus interconnection service" (SIS), with respect to established interconnection service connecting an electric generating facility with an electric transmission system, as any portion of that service that: (1) has not been used; and (2) is not reasonably expected to be needed; the use of which would result in the total amount of interconnection service at the point of interconnection remaining the same. Provides that an electric utility that is required to file integrated resource plans (IRPs) with the Indiana utility regulatory commission (IURC) must include in any IRP filed after December 31, 2029, an analysis of the potential for SIS to meet immediate needs for capacity and energy at utility owned facilities. Provides that with respect to any petition filed with the IURC after December 31, 2029, for a certificate of public convenience and necessity for the construction, purchase, or lease of an electric generation facility, the IURC shall consider whether: (1) the petitioner has conducted an analysis of the use of SIS as an alternative to, or in conjunction with, the proposed construction, purchase, or lease of the facility; and (2) the proposed construction, use, or lease of the facility will make use of, or allow for the use of, SIS. Requires the IURC to conduct a study to evaluate the potential use of SIS by electric utilities. Sets forth specific topics that the IURC must evaluate as part of the study. Requires the IURC to include in its 2027 annual report its findings with respect to the topics evaluated in the study.