Participating transmission owner (PTO)

Transmission owners can elect to turn operational control of their facilities over to the ISO and collect access charges from users. The ISO and adjacent balancing authorities may allow certain generating facilities to dynamically schedule across interties into the ISO balancing authority area so these facilities can participate in the ISO real-time market.

Become a participating transmission owner

Submitted applications

See applications submitted to California ISO by transmission owners.

Transmission control agreement

The terms and conditions for how the ISO and participating transmission owners will discharge their respective duties and responsibilities. View the Transmission control agreement and Appendix F.

Transmission modeling

The Resource Interconnection Management System (RIMS) transmission modeling process is designed to assist each Participating Transmission Owner (PTO) with modeling related design changes and implementation of the ISO Full Network Model (FNM). 

The Market Participant Asset Implementation Process Guide provides a high level understanding of participating in the ISO Full Network Model process from a design and implementation standpoint.

The Transmission Asset Implementation Guide provides guidance on deliverables and clarifies why a deliverable is required to be submitted. Each PTO must report all transmission changes to the ISO in accordance to BAL-005 and TOP-001

PTOs may fall into two categories that requires participation in the modeling process.

Existing PTO

• Asset additions, modification and removals that affect the ISO controlled grid
• Project information provided by existing Participating Transmission Owners

New PTO

• Asset additions that affect the CAISO controlled grid (i.e. Competitive Solicitation)
• Project information provided by new Participating Transmission Owners

Transmission operations

Transmission access charge (TAC)

Charges assessed, on behalf of the Participating Transmission Owner, to parties who require access to the ISO grid. View the high voltage access charge rates and wheeling access charge rates on the Settlements page.

The ISO filed Amendment 27 to the ISO Tariff on March 31, 2000 to propose a new methodology to calculate transmission access charges for Participating Transmission Owners.