SPP's RTO Expansion (RTOE) is now live, and market participants are beginning to evaluate early impacts across the expanded footprint. In our SPP RTOE retrospective webinar, we discussed early observations, key market developments, and what we're learning from the first months of operation. Here are answers to the most frequently asked questions from that discussion.
Frequently Asked Questions
General
1. SPP has issued several Resource Advisories for SPP West since the RTOE go-live. Can you summarize the specific events and any common themes?
All three Resource Advisories referred to high variability caused by "wind drop events". One of the three advisories also forecasted extreme temperature swings. Managing this type of load uncertainty requires flexible capacity. SPP uses its Uncertainty Reserve product to procure upward flexible capacity to manage net load variation, particularly during the morning and evening ramp periods.
2. How will the Regulation Ancillary Services differ between SPP East and SPP West?
Regulation ancillary services follow the same market rules across the entire RTO footprint. However, the specific requirements, pricing, and certain settlement calculations are managed at the BAA and/or reserve zone level. For more details, see SPP Integrated Marketplace Protocols v118.1 sections 4.1.3, 4.1.5.
LMPs
3. Does the west expansion affect SPP South and SPP North LMPs materially? Is SPP ISO bifurcated, or is the interconnectivity meaningful enough to impact traditional SPP hub prices?
The SPP South and North LMPs have not been significantly impacted by the RTOE. We have seen an increase in congestion volatility in SPP North since the go-live, but that is likely not due to the addition of the SPP West BAA. However, we expect the dual-BAA capability of sharing wind generation and ramp flexibility across the two BAAs will help support more robust pricing signals across the ISO over time.
Physical Trading
4. How will interchange between SPP West and CAISO's neighboring EDAM BAAs function?
No specific changes have been made to the interchange process between SPP West and EDAM BAs. CAISO has indicated that seams management and coordination is a top priority, but there have not been any changes made to the "market-to-market" coordination process between the regions. In the near term we do not expect EDAM BAs to behave differently than other WECC BAs as a result of SPP's expansion.
5. Is e-tagging no longer allowed across the tie?
Physical e-tagging will no longer occur across the ties and will be scheduled from market optimization.
Virtuals Trading
6. What is the impact of SPP RTOE on the virtual market? When can traders place virtual trades on the SPP West nodes?
There are about 299 new tradable virtual nodes for SPP West. These nodes were tradable in the virtual market March 31 for the first operating day April 1. The new tradable nodes for SPP West can be found here.
Congestion Revenue Rights (CRR) Changes
7. If the DC Tie constraints bind at the BAA-level, how will the TCR market hedge against DA congestion for the source-to-sink paths across the DC ties?
There will be a transitional 4-year period after which the paths that span across the DC ties will be tradeable in the TCR Market. Unlike positions across the AC portions of the grid, positions across the DC ties will be settled as options instead of obligations, providing only financial upside to the rights holder. Rather than hedging on the marginal congestion component of the LMP to settle the paths across the seam, the DC tie segments will be settled using the DC tie shadow price. This is a significant departure from traditional congestion hedging. The DC tie shadow price represents the capability of the DC tie to relieve total system production cost. If there is no congestion on the tie, the shadow price will simply be $0/MWh.
8. Real-Time Interchange often leads to uneconomic trades for both SPP East and West. What improvements are being considered in the future, from a market design perspective?
SPP is currently working on implementing Real-Time Dispatchable Transactions (RTDT), which will introduce dynamic scheduling using 5-minute real-time dispatch. Market participants will be able to combine RT LMPs and net actual interchange to submit price-sensitive interchange offers that clear every 5 minutes across the boundaries. This change will create a significant improvement over static hourly schedules, increasing seam transaction efficiency and yielding significant production cost savings.
As the West continues to split into new DA markets (SPP RTO West, Markets+ and EDAM), managing market seams efficiently will require formal seams agreements, or Market-to-Market (M2M) coordination. The first phase of EDAM, along with SPP's RTOE, is critical because future M2M agreements will require accurate pricing data from the interface nodes to manage data sharing, coordinate congestion management, and track transmission rights usage across the interconnected regions.
9. How is the TCR market impacted by SPP RTOE?
The TCR market rules will remain consistent for paths that are contained in each BAA. The nomination cap will be set by SPP West capabilities, sharing the standard business-as-usual procedure for TCRs as SPP East operations. However, the source-to-sink paths that cross the DC Ties will undergo a four-year transition period. During this time, congestion hedging will be based on long-term Transmission Service Rights (TSRs) and settled as an option. The holders of these rights will be automatically awarded. So we will not have offer/bid data for these specific paths that will not reach the TCR market until after the four-year transition period.
10. When was the first TCR auction that will reflect the new RTOE locations?
The SPP West footprint and three internal DC Ties first showed up in the annual ARR allocation process, which opened on April 1, 2026. RTO Expansion-related FTR data first showed up in the Annual TCR/FTR auction (results published May 22, 2026).
Learn More
For a deeper look at the changes introduced by RTOE refer to our previous blog SPP RTO Expansion Frequently Asked Questions.
Have more questions about the expanded market footprint or how to analyze it effectively? Talk with a Yes Energy expert to learn how our data and insights can help you navigate SPP RTOE.
