Transmission Pricing Methodology amendments 2026

This consultation sought feedback on seven targeted amendments to the Transmission Pricing Methodology (TPM) that would better align transmission charges with benefits, increase predictability and reduce administrative costs.

Three proposals were identified by the Authority and four were requested by Transpower through Workstream 1 of its TPM Operational Review.

Authority proposals:

1. refining the simple method treatment of battery storage, to ensure battery storage is not charged disproportionately compared to other supply technologies
2. improving the allocation of costs of anticipatory connection capacity, so benefit-based charges (BBCs) are better targeted to expected beneficiaries
3. removing the two-year lag between when a new weighted average cost of capital applies to a new regulatory control period and when the TPM requires Transpower to start applying it to calculate BBCs

Transpower Operational Review proposals:

1. processing all BBC adjustment events in one annual batch
2. removing the substantial sustained increase adjustment event for BBCs
3. extending the first simple method period to enable Transpower to bring forward a review of BBC methods
4. amending legal drafting to improve clarity and remove redundant provisions.

We welcomed submissions for six of the seven proposals by 24 July 2026 with one late submission accepted from Lodestone Energy Limited, and by 7 August 2026 for the proposal on anticipatory capacity for connection assets.

We expect to make a decision on six of the seven proposals in November 2026, allowing Transpower to incorporate any changes into its 2027/28 prices. We plan to decide on the proposal for anticipatory capacity in early 2027, as we expect more substantive submissions and will need more time for analysis.