CA AB1408

Requires the Independent System Operator (ISO) to integrate surplus interconnection service considerations into long-term transmission planning and enhance transparency around surplus interconnection service opportunities

Mandates electrical corporations and local publicly owned electric utilities with annual electrical demand exceeding 700 gigawatthours to evaluate and consider surplus interconnection service options in their integrated resource plans

Requires electrical corporations and local publicly owned electric utilities to use available grid infrastructure through surplus interconnection service, including adding renewable energy resources or battery storage at or near fossil plants, to utilize any available interconnection capacity when feasible

Defines "surplus interconnection service" as any unneeded portion of interconnection service capacity established in a large generator interconnection agreement where the total interconnection service capacity at the point of interconnection remains unchanged

Aims to maximize adoption of federal investment tax credits and federal production tax credits through better utilization of existing grid interconnection capacity