Co-Located Large Loads: Tariff Design Before the Next Data-Centre Wave

Large loads co-located with generation have moved from niche arrangements to a central market-design problem. Technology firms want speed and firm power. Generators want new offtake. Other retail customers want assurance they are not paying for private campuses. By autumn 2025 the outlines are clear even before any later nationwide show-cause climax: opaque, case-by-case deals will not scale, and RTOs need transparent tariff language for high-impact loads and electrically proximate generation. If a campus requires network upgrades, the campus should face those costs unless a transparent shared-benefit finding says otherwise.

If a co-located generator reduces network use, credits must be measured, not assumed. Generator interconnection under Order No. 2023 and load interconnection processes must be studied together when electrically proximate. It can also create new contingencies if a large load and its host generator trip together or if islanding assumptions fail. Transparent tariff language beats clever private contracts when the volumes at stake can move zonal prices and reserve margins.