Skip Ribbon Commands
Skip to main content
Sign In
Home > Stay Informed > Stakeholder Processes > Variable Operations and Maintenance Cost Review

Variable operations and maintenance cost review

Every three years, the California ISO evaluates the operations and maintenance cost adder used for proxy commitment costs and default energy bids to ensure the values still reflect resources’ variable costs. Stakeholders will have an opportunity to review and comment on the methodology used to calculate updated variable operations and maintenance adders.

Process status

Report: in progress


Current meeting

There is no meeting currently scheduled.





Initiative outcome

Effective date: Trading day Apr 01, 2012
FERC approval: Mar 15, 2012
Tariff amendment filing: Jan 13, 2012 (ER12-806)
Board of Governors approval: Dec 15, 2011
On Mar 29, 2012 the ISO revised its default operations and maintenance cost adders, which represent the per-megawatt hour variable, non-fuel costs of running a generating unit at or above its minimum operating level. The ISO increased the number of adder values from two to ten to differentiate costs by technology for all generation resources participating in the market. The ISO will re-evaluate these values every three years.