Not an official release, and these scores will change. The index is under active build: the methodology is still being revised and the numbers shown here predate corrections already made to it. Shared for feedback, not yet for citation or redistribution. Built on trailing 4 quarters ending 2026Q2 with partial current-quarter data.
Grid Flexibility Index
Where grid flexibility is worth the most, and where the grid can actually use it.
Opportunity is how much flexibility value a grid needs. Readiness is whether that value can be activated and paid. Two scores, never blended. The quadrant is a reading aid, and readiness varies far more across US grids than opportunity does, which is the finding.
Price factors on trailing 4 quarters ending 2026Q2 · Preview · Generated 2026-08-13 · Boundary fixed 5 / 5
Capacity and transmission are on their own vintage, not this window: per-factor detail
`window_basis` above (trailing 4 quarters ending 2026Q2) describes the BACKWARD-looking price factors only (V2 energy, V3 ancillary, S1/S7/S8 stress, M4 momentum). Two factor families that together are roughly 63% of the value pool run on their own clocks: V1 capacity prices to the latest-cleared forward auction, and V4 transmission prices to the latest annual tariff filing (2026). S4 (large-load growth) is scored from a 5-year forecast window (2026-2031). Per-factor vintages are declared individually below, never collapsed into one basis.
| Factor family | Vintage | Window / as-of |
|---|---|---|
| V1 Capacity (Opportunity: Value) | forward-auction | delivery years 2025-2027 (latest cleared per ISO: CAISO 2026 (CPUC RA Report / MPB), ISONE 2027 (FCA 18), MISO 2026 (MISO PRA 2026/2027), NYISO 2025 (ICAP Spot), PJM 2027 (RPM BRA), SPP 2025 (SPP MMU CT net-revenue-gap proxy)); native constructs, not uniform forward-cleared auctions: CAISO = bilateral RA (CPUC MPB), NYISO = spot ICAP, SPP = net-revenue-gap proxy; PJM/MISO/ISONE are true forward-cleared auctions (RPM BRA / PRA / FCA) |
| V2 Energy (Opportunity: Value) | backward-ttm | trailing 4Q ending 2026Q2 |
| V3 Ancillary (Opportunity: Value) | backward-ttm | trailing 4Q ending 2026Q2 |
| V4 Transmission (Opportunity: Value) | latest-annual-filing | latest filed/effective rate per ISO: CAISO volumetric_recovery_zero_peak_avoidance, ERCOT zone_meter_proxy_weighted_2026_n4, ISONE system_2026, MISO system_2026, NYISO volumetric_recovery_zero_peak_avoidance, PJM zone_avg_2026_n20, SPP system_2026; CAISO/NYISO structurally $0 (volumetric recovery, no coincident-peak avoidance); SPP = net-revenue-gap proxy (not a forward-cleared auction; see Q13(b)) |
| S1 Congestion (Opportunity: Stress) | backward-ttm | trailing 4Q ending 2026Q2 |
| S7 Surplus (Opportunity: Stress) | backward-ttm | trailing 4Q ending 2026Q2 |
| S8 Winter Fuel (Opportunity: Stress) | mixed (ttm ratio + latest-annual fleet) | trailing 4Q ending 2026Q2 ratio + latest EIA-860M gas fleet (ISONE ratio partial-window, S8 scored gas-share-only; see per-ISO disclosure) |
| S4 Large-Load Growth (Opportunity: Momentum) | forward-auction | 2026-2031 total net peak growth |
| M4 Flexibility (Opportunity: Momentum) | latest-annual-filing | EIA-860M 2026-01 + EIA-861 2024 |
| A1 AMI (Readiness: Infra) | latest-annual-filing | EIA-861 2024 |
| A2 Time-Varying Rates (Readiness: Rate) | latest-annual-filing | EIA-861 2024 / PtC availability (ERCOT) |
| A4 Retail DR (Readiness: Program) | latest-annual-filing | EIA-861 2024 |
| A5 Wholesale DR (Readiness: Market) | latest-annual-filing | FERC/EIA-861 2024 |
| A6 Realization (Readiness: Program) | latest-annual-filing | EIA-861 2024 |
| A7 Aggregation (Readiness: Market) | point-in-time-status | status as of 2026-08-13 |
| A9 Incentive (Readiness: Institutional) | point-in-time-status | status as of 2026-08-13 |
| A10 Retail Choice (Readiness: Institutional) | point-in-time-status | status as of 2026-08-13 |
This release, PJM and SPP hold the largest untapped grid-flexibility value: the worth is high, the readiness to deliver it is low. CAISO is the most activated.
PJM
UntappedFull ranking
Sort by any column. Click a grid to expand its pillars.| Grid | Opportunity ▼ | Readiness | Quadrant | Confidence | Opp. range | Data grade | Factors |
|---|---|---|---|---|---|---|---|
| PJM | 6.37 | 3.74 | Untapped | 98% | 6.1-6.8 | High / Medium | 19/20 |
| SPP* | 6.09 | 4.90 | Untapped | 44% | 5.8-6.5 | High / Medium | 19/20 |
| MISO* | 5.63 | 4.77 | Untapped | 61% | 5.4-6.3 | High / Medium | 19/20 |
| ISONE* | 5.04 | 3.86 | Untapped | 69% | 4.6-5.9 | High / Medium | 19/20 |
| NYISO* | 4.34 | 5.31 | Activated | 83% | 4.1-4.8 | High / Medium | 19/20 |
| ERCOT* | 3.86 | 4.91 | Monitor | 46% | 3.6-4.3 | High / Medium | 19/20 |
| CAISO | 3.80 | 7.43 | Activated | 100% | 3.7-4.1 | High / Medium | 19/20 |
How to read the quadrant
Each cell answers a different reader's question.Untapped
high opportunity · low readinessThe reform target. Large, measured value locked behind rate design and market access. Where regulators and advocates should look first, and where the index earns its name.
Ready to scale
high opportunity · high readinessOperator entry territory. The value is large and reachable now. Deployment data should accumulate fastest here, which is also the index's own validity check.
Monitor
low opportunity · low readinessWatch the momentum. Neither the value nor the enablement case is strong yet. The question is which axis moves first.
Activated
low opportunity · high readinessSuccess, not failure. The enabling infrastructure is built and the value is already being captured or compressed. The index reads this correctly.
Disclosures
What to hold lightly, stated plainly.ERCOT: Monitor on the trailing 4 quarters ending 2026Q2 basis; reads Untapped on a multi-year energy/ancillary basis. The label is window-sensitive; the published basis is declared and applied identically to all seven ISOs.
ERCOT: Monitor, within 0.08 of the quadrant boundary on the opportunity axis. Read the bands, not the cell.
ERCOT: Activated in 54% of specified sensitivity draws; Monitor in 46%. The share reflects the specified perturbations only, not all evidence uncertainty. Read the P10-P90 bands beside the label.
MISO: Untapped in 61% of specified sensitivity draws; Ready to scale in 38%. The share reflects the specified perturbations only, not all evidence uncertainty. Read the P10-P90 bands beside the label.
NYISO: Activated in 83% of specified sensitivity draws; Monitor in 15%. The share reflects the specified perturbations only, not all evidence uncertainty. Read the P10-P90 bands beside the label.
ISONE: Untapped on the trailing 4 quarters ending 2026Q2 basis; reads Monitor on a multi-year energy/ancillary basis. The label is window-sensitive; the published basis is declared and applied identically to all seven ISOs.
ISONE: Untapped, within 0.04 of the quadrant boundary on the opportunity axis. Read the bands, not the cell.
ISONE: Untapped in 69% of specified sensitivity draws; Monitor in 29%. The share reflects the specified perturbations only, not all evidence uncertainty. Read the P10-P90 bands beside the label.
SPP: Untapped, within 0.10 of the quadrant boundary on the readiness axis. Read the bands, not the cell.
SPP: Ready to scale in 56% of specified sensitivity draws; Untapped in 44%. The share reflects the specified perturbations only, not all evidence uncertainty. Read the P10-P90 bands beside the label.
CAISO is scored on 19 of 20 factors. Its missing factors need multi-year price history the market does not yet have. The weighted geometric mean re-weights over the scored factors, and the gap is shown, never hidden.
ERCOT is scored on 19 of 20 factors. Its missing factors need multi-year price history the market does not yet have. The weighted geometric mean re-weights over the scored factors, and the gap is shown, never hidden.
PJM is scored on 19 of 20 factors. Its missing factors need multi-year price history the market does not yet have. The weighted geometric mean re-weights over the scored factors, and the gap is shown, never hidden.
MISO is scored on 19 of 20 factors. Its missing factors need multi-year price history the market does not yet have. The weighted geometric mean re-weights over the scored factors, and the gap is shown, never hidden.
NYISO is scored on 19 of 20 factors. Its missing factors need multi-year price history the market does not yet have. The weighted geometric mean re-weights over the scored factors, and the gap is shown, never hidden.
ISONE is scored on 19 of 20 factors. Its missing factors need multi-year price history the market does not yet have. The weighted geometric mean re-weights over the scored factors, and the gap is shown, never hidden.
SPP is scored on 19 of 20 factors. Its missing factors need multi-year price history the market does not yet have. The weighted geometric mean re-weights over the scored factors, and the gap is shown, never hidden.
ISONE (S8_winter_fuel): ISO-NE had not yet published June 2026 SMD hourly load at this release's cutoff, so the S8 winter/summer peak-ratio leg (one of S8's two sub-factors) is omitted for this release. S8 is scored gas-share-only under a disclosed partial-window allowance (GFI_ALLOW_PARTIAL_WINDOW). ISONE's factor coverage is reported as 19-of-20 plus one partial (not a plain 20/20), and its Opportunity score and quadrant are PROVISIONAL pending the recompute once ISO-NE appends June and the full S8 ratio is restored.
Key statistics
Cite-ready, caveats included.- According to the Grid Flexibility Index (2026Q2), PJM scores 6.37 on Opportunity (range 6.1-6.8) and 3.74 on Readiness, placing it in the Untapped quadrant with 98% confidence. Data grades: Opportunity High, Readiness Medium.
- According to the Grid Flexibility Index (2026Q2), SPP scores 6.09 on Opportunity (range 5.8-6.5) and 4.90 on Readiness, placing it in the Untapped quadrant with 44% confidence. Data grades: Opportunity High, Readiness Medium.
- According to the Grid Flexibility Index (2026Q2), MISO scores 5.63 on Opportunity (range 5.4-6.3) and 4.77 on Readiness, placing it in the Untapped quadrant with 61% confidence. Data grades: Opportunity High, Readiness Medium.
- According to the Grid Flexibility Index (2026Q2), ISONE scores 5.04 on Opportunity (range 4.6-5.9) and 3.86 on Readiness, placing it in the Untapped quadrant with 69% confidence. Data grades: Opportunity High, Readiness Medium.
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