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Five well outlined steps will help you join the Western Energy Imbalance Market (WEIM) real-time market. Because the platform is scalable and flexible, entities can join in a timeframe that works for their business. California ISO (ISO) experts will support you every step of the way, and existing WEIM participants have offered their support for new entrants to help them navigate participation in the WEIM.


Perform cost benefit analysis

A key step in deciding to participate as a WEIM entity is determining the costs and benefits. This may involve performing a cost-benefit analysis that includes multiple scenarios, estimated implementation costs and benefits for the prospective entity, the ISO and other WEIM entities. The ISO will share information on estimating costs based on experience of other WEIM participants. Below are some recent examples from others who have completed the benefit analysis.


Establish an implementation agreement

After you decide to proceed with participation, we will jointly establish an implementation agreement and file it with the Federal Energy Regulatory Commission (FERC). This agreement outlines the terms of our partnership to prepare for your participation. The agreement also outlines schedule milestones and associated payments to the ISO for costs for related system changes, software licenses and other configuration activities.

Find examples in this list of executed WEIM implementation agreements.


WEIM Implementation documents >>

Train for WEIM

Together we will develop and deliver an organized training curriculum for your staff. Experienced ISO staff will train your in-house training or end-user staff through online and instructor led courses and workshops covering all aspects of WEIM, including market design, market operations, scheduling, and settlements. In the interim we recommend your staff take the below online introduction courses.


Get ready to participate
in the WEIM​

Advanced training modules >>

​Establish operating procedures

We will collaboratively develop operating procedures prior to implementation to ensure operational readiness. You will have the opportunity to practice with business process changes and exercise operational procedures during table top training scenarios and market simulation. Operating procedures must be established and training completed prior to the start of parallel operations.


Complete the implementation process

The implementation process takes approximately 18 months and includes the below activities, which often run in parallel.


Plan for implementation

Together we will develop a detailed project schedule outlining all the steps leading to the market simulation, parallel operations and full participation. At this point you should consider the following:


  • staffing and project roles to manage WEIM preparations

  • IT and operations project implementations

  • whether or not to engage a third party to assist with systems development and integration

  • impact to open access transmission tariff (OATT) and potential stakeholder processes to adapt it

  • a participating resource strategy to determine which resources will participate in WEIM through individual bids


Establish agreements and identify scheduling coordinator and participating resources

As a WEIM entity, your organization must enter into contracts with the ISO. Likewise, all resources that plan to participate and provide bids must become a WEIM participating resource by entering into standard contracts. Both your organization and participating resources will need to select scheduling coordinators, who will directly bid or self-schedule into WEIM and handle the settlement process.


Integrate with the ISO full network model

We will work closely with you to accurately integrate your network model into the ISO full network model, which is essential for economic resource dispatching.  You will have an opportunity to test connectivity and see the market model prior to market simulation testing.


Implement metering

To support your overall success, the ISO’s goal is to assist you in implementing the various metering requirements and processes based on your selected participation role as either a CAISO Metered Entity (CAISOME) or a Scheduling Coordinator Metered Entity (SCME). Information and requirements can be found within the ISO Tariff Section 10 - Metering, and within our related Business Practice Manual for Metering under the related participation role.


Modify impacted systems

You will need to modify your operating and bid-to-bill systems associated with WEIM participation to enable reliable ISO control and accurate settlements.  Affected systems include, but are not limited to, the energy management system, forecasting, scheduling, dispatch, outage management and settlements.

Perform testing

Together we will perform system integration, security and functional testing of all impacted systems and processes. During market simulations we test both the system and market interplay between the ISO and your participating resources under simulated market conditions. We will publish a market simulation test plan outlining scenarios, a timeline and expected actions prior to testing.

Certify readiness, conduct parallel operations and transition to binding WEIM production

The ISO will work with you to develop an activation readiness plan that includes a “go-live” schedule, system activation steps, communication protocols and a robust support plan. We will jointly track progress and report preliminary results during market simulation and parallel operations. We will also assist with the certification to FERC that the market simulation and parallel operations have demonstrated that systems and operations personnel are ready to operate as anticipated.


Contact us

ISO staff is here to assist you in every aspect of implementation. If you need additional information on participating in the WEIM, please contact:


Adam Schultz


Computer Based Training (CBT)