Reliability Unit Commitment (RUC) - CIMView

Register Here During GCPA : Register

Reliability Unit Commitment (RUC)

Table of Contents

The Gist

ERCOT performs studies every hour looking into the rest of the day (and later in the day into the next day as well).  The studies use load, wind and solar forecasts and also Qualifying Scheduling Entities’ (QSE’s) submitted Current Operating Plans (COPs) to look for situations where there will be irresolvable transmission problems or insufficient online capacity with the current committed resources (and quick start units regardless of COP status, if studies run more than an hour ahead)  in the COPs.  If either of those cases exist, ERCOT will then determine if there is no longer sufficient time to allow resources to change their COPs by themselves in reaction to market conditions.  Should all that be true, ERCOT will issue RUC instructions to resources that can solve the problems.  Should a resource receive a RUC instruction it is obligated to come online (or stay online if it already is online and was planning to come off).  

Prior to coming online/extending its online status, a RUC’d resource has to decide whether or not to “Opt Out”.  Should a resource not “Opt Out” it will be guaranteed to at least make its variable costs back, though it will get all or half of its profits clawed back.  It also has to offer its energy at a minimum of $1500/MWh.  On the other hand, should a resource choose to “Opt Out” it will not be guaranteed to break even, it will not get any profits clawed back, and it will not be subject to a minimum offer floor.  

NPRR1092, if passed, would significantly change the RUC process by removing the “Opt Out” option and lowering the offer floor to $75 (initially, upon system implementation it changes to 18*Fuel Index Price).

Important Actions

  • 4/4/22 ERCOT sends out a market notice noting that the RUC clearing engine has been using the wrong offer costs since 2016.



Meeting Notes

4/6/22 WMS

2/24/22 WMWG

11/15/21 CMWG

10/25/21 WMWG

10/18/21 CMWG


Send any corrections/clarifications to