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ERCOT Solar & Wind Curtailment Analysis | Generated 2026-07-25 08:16 | All Available Data
Source: ERCOT 60-Day SCED Disclosure | Definition: curtailment = max(0, HSL - Base Point)
==============================================================================================================
DATA COVERAGE:
SCED curtailment : 2024-02-01 through 2026-05-25
EIA generation : through 2026-06
Hub prices : through 2026-07-24
2026 figures are for available data only -- raw MWh cannot be compared
to full-year 2024/2025 totals without annualizing (which this report does not do).
SAMPLING CAVEAT:
SCED changed from 15-min to 5-min intervals ~Dec 2025; older MWh normalized ×3.
Cross-year MWh comparisons are sampling estimates. TRUST RATES (%), NOT LEVELS.
EIA-derived value factors and revenue are unaffected (independent data source).
##############################################################################################################
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Seasonal Overview | All Quarters | Every Available Year
==============================================================================================================
Combined solar+wind curtailment normalized MWh. Value factors = capture / demand-weighted avg price.
Year Q1 Q2 Q3 Q4
Curt MWh Rate SolVF WndVF Curt MWh Rate SolVF WndVF Curt MWh Rate SolVF WndVF Curt MWh Rate SolVF WndVF
----------------------------------------------------------------------------------------------------------------------------------------
2024 2.09TWh 7.2% 0.855 0.800 2.88TWh 6.2% 1.193 0.705 0.50TWh 1.3% 1.136 0.817 2.34TWh 5.5% 1.002 0.812
2025 3.44TWh 7.5% 0.744 0.861 3.22TWh 6.0% 0.889 0.886 0.77TWh 1.7% 0.985 0.886 2.51TWh 5.4% 0.888 0.838
2026 4.66TWh 8.7% 0.456 0.676 1.49TWh 6.8% 0.911 0.915 0.00TWh 0.0% — — 0.00TWh 0.0% — —
Rate % = curtailed/available (sampling-invariant -- TRUST THIS for cross-year comparison).
Curt TWh = estimated MWh (normalized); absolute levels are estimates, not measurements.
SolVF/WndVF = solar/wind value factor vs demand-weighted grid avg (EIA-based, unaffected).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
DEC 2025: THREE CHANGES ON ONE DATE | DO NOT CONFLATE | READ FIRST
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
NOTE FOR FUTURE ANALYSTS / AI MODELS: THREE unrelated changes hit ERCOT data
within days of 2025-12-05. Every 2025->2026 delta straddles all three.
Treat any single-cause story with suspicion.
(1) SCED DISCLOSURE CADENCE (15-min -> 5-min, ~Dec 2025).
MEASUREMENT change. Inflates raw MWh ~3x. Handled via x3 normalize;
use RATES, not levels. Affects how curtailment is COUNTED.
(2) RTC+B GO-LIVE (Operating Day 2025-12-05, PUCT 48540).
MARKET-DESIGN change. AS now co-optimized with energy in real-time SCED
every interval; ESRs slide between energy and AS positions live.
Affects how the grid is RUN.
- Legacy COP statuses retired (ONREG, ONDSR, ONRR, OFFNS, etc.).
- First-ever real-time AS price signal produced directly by SCED.
- Largest ERCOT market redesign since nodal launch ~15 years prior.
(3) EIA-930 ESR ATTRIBUTION (coincident, ~Dec 2025).
REPORTING change. Pre-Dec-2025 the EIA battery fuel series UNDER-COUNTED
charging (battery net generation ran +400 to +750 MW monthly mean --
batteries are net SINKS; this cannot be real behavior). Charging that was
metered on the Load-Resource side did not land in the battery series until
reporting changed around Dec 2025 (exact mechanism not established here).
Affects how battery flow is ATTRIBUTED, not how batteries actually ran.
SPECIFIC FALSE SIGNAL -- DO NOT REPEAT:
The EIA battery hour-of-day shape appears to 'flip' from discharge-leaning
to deep midday charging at 2025-12-05. This is NOT confirmed behavioral
change and is NOT reliable evidence of RTC+B arbitrage on its own.
Independent GridData.BatteryCharge (charge-only telemetry) shows the fleet
ALREADY charging -3,000 to -3,800 MW midday throughout Jun-Nov 2025
(PRE-RTC+B). The batteries were absorbing midday solar the whole time;
only the REPORTING changed in December.
Any claim that 'batteries flipped to absorbing solar after RTC+B' based on
EIA-930 net flow alone is confounding change (3) with change (2).
CONSEQUENCE:
The entire 2026 column is the first post-RTC+B AND post-attribution season.
Specifically suspect (do NOT assume physical causation):
- % of Potential rising ~3-5x (2025->2026)
- Net-Load Saturation Index jump
- Negative-price curtailment share increase
- DAM vs RTM capture gap (RT prices now embed AS opportunity cost)
- Voluntary/involuntary and oversupply/congestion driver classification
- ALL battery hour-of-day / net-flow deltas
WHAT IS NOT KNOWN:
This report does not decompose how much of any 2025->2026 shift is (1) vs
(2) vs (3). RTC+B's true mechanism -- real-time energy<->AS co-optimization
-- is NOT visible in aggregate net-flow or fuel-mix series. It lives only in
SCED ESR dispatch + AS award data. Proving a genuine RTC+B behavioral change
requires the pre-Dec-5 SCED ESR stitch PLUS AS awards; not attempted here.
Source: ERCOT Market Notices M-F110525-01..-04; PUCT 48540; EIA-930 (battery
energy-source category added 2024Q3, ERCOT separate reporting Oct 2024).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
==============================================================================================================
Data Quality | All Available Data
==============================================================================================================
IMPORTANT CAVEAT ON ABSOLUTE MWH NUMBERS:
ERCOT's 60-day SCED disclosure switched from 15-min intervals (4/hr) to 5-min (12/hr)
around Dec 2025. The MWh totals below are ESTIMATED by multiplying old 4-interval data
by 3 to match the new 12-interval baseline. This makes the series self-consistent but
the absolute levels are assumptions, not measurements.
--> USE RATES (curtailment %) FOR CROSS-YEAR COMPARISON, not absolute MWh.
The rate (curtailed/available) is sampling-invariant; the ×3 factor cancels.
--> Metrics from EIA data (value factor, revenue) are unaffected -- different source.
Avg intervals/resource per hour by month:
Month Fuel Avg ipr Norm Factor Quality
-------------------------------------------------------
2024-02 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-02 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-03 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-03 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-04 solar 4.00 3.001 15-min SCED (x3 corrected)
2024-04 wind 4.00 3.001 15-min SCED (x3 corrected)
2024-05 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-05 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-06 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-06 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-07 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-07 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-08 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-08 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-09 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-09 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-10 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-10 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-11 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-11 wind 4.00 3.000 15-min SCED (x3 corrected)
2024-12 solar 4.00 3.000 15-min SCED (x3 corrected)
2024-12 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-01 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-01 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-02 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-02 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-03 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-03 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-04 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-04 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-05 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-05 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-06 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-06 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-07 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-07 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-08 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-08 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-09 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-09 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-10 solar 4.00 3.002 15-min SCED (x3 corrected)
2025-10 wind 4.00 3.002 15-min SCED (x3 corrected)
2025-11 solar 4.00 3.000 15-min SCED (x3 corrected)
2025-11 wind 4.00 3.000 15-min SCED (x3 corrected)
2025-12 solar 11.03 1.088 FULL (5-min SCED)
2025-12 wind 11.03 1.088 FULL (5-min SCED)
2026-01 solar 11.79 1.018 FULL (5-min SCED)
2026-01 wind 11.79 1.018 FULL (5-min SCED)
2026-02 solar 12.13 0.989 FULL (5-min SCED)
2026-02 wind 12.13 0.989 FULL (5-min SCED)
2026-03 solar 11.76 1.020 FULL (5-min SCED)
2026-03 wind 11.76 1.020 FULL (5-min SCED)
2026-04 solar 11.29 1.062 FULL (5-min SCED)
2026-04 wind 11.29 1.062 FULL (5-min SCED)
2026-05 solar 12.06 0.995 FULL (5-min SCED)
2026-05 wind 12.06 0.995 FULL (5-min SCED)
==============================================================================================================
PART 1: SOLAR ECONOMICS TREND | Monthly Capture Price by Hub
==============================================================================================================
'Capture price' = $/MWh actually earned by ERCOT-system generation of this fuel,
priced at the named hub (a locational proxy -- see Part 7, POV note [5]).
DAM is the trend/extrapolation basis (RTM has real 2026 gaps -- Part 7, POV [3]);
RTM capture is also shown per month wherever coverage is usable (>=50% of DAM hours).
VERDICT: HB_SOUTH solar capture fell from a FITTED $30.61/MWh (2024-02) to $28.03/MWh (2026-06), trending $-1.11/MWh per year (-3.6%/yr of the 2024-02 fitted base).
(Raw single-month values were $10.89/MWh in 2024-02 and $30.16/MWh in 2026-06 -- noisier than the fit; see the table below for every month.)
NAIVE 12-MONTH EXTRAPOLATION (straight-line fit on 29 months of HB_SOUTH DAM capture, 2024-02-2026-06): $26.92/MWh.
HONESTY CAVEAT: a linear fit on a short, noisy monthly series is NOT a forecast.
It ignores mean reversion, the new-build interconnection queue, load growth, and
the RTC+B market-design change (see the DEC 2025 warning above). Read it as 'which
way the line currently points', not a number to underwrite a 50-year decision on.
--- HB_SOUTH ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 10.89 10.16 100.0% 2,642,848
2024-03 18.66 14.91 100.0% 3,268,150
2024-04 26.85 27.25 100.0% 3,465,167
2024-05 63.43 56.54 100.0% 4,087,103
2024-06 43.38 35.86 100.0% 4,970,234
2024-07 27.60 27.20 100.0% 5,139,716
2024-08 46.81 46.82 100.0% 5,789,394
2024-09 25.14 24.06 100.0% 4,827,626
2024-10 33.97 29.74 100.0% 4,831,241
2024-11 22.21 24.97 100.0% 3,495,104
2024-12 19.46 19.54 100.0% 3,001,129
2025-01 22.13 19.20 100.0% 3,311,790
2025-02 20.79 17.67 100.0% 3,656,364
2025-03 25.71 19.82 100.0% 5,138,950
2025-04 24.39 19.31 100.0% 5,275,562
2025-05 31.93 30.05 100.0% 6,508,623
2025-06 27.74 25.96 100.0% 6,957,597
2025-07 32.14 30.37 100.0% 7,217,379
2025-08 44.63 40.47 100.0% 7,421,005
2025-09 31.55 30.18 100.0% 6,939,612
2025-10 36.60 38.06 100.0% 6,159,690
2025-11 35.43 36.14 100.0% 4,875,312
2025-12 24.57 23.19 100.0% 4,013,625
2026-01 30.83 20.35 96.8% 4,543,845
2026-02 11.23 10.40 100.0% 5,352,788
2026-03 19.01 18.60 100.0% 6,729,090
2026-04 36.04 39.21 100.0% 5,743,260
2026-05 26.85 24.39 100.0% 7,804,637
2026-06 30.16 29.99 63.5% 4,769,073
--- HB_WEST ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 10.99 10.46 100.0% 2,642,848
2024-03 19.14 14.83 100.0% 3,268,150
2024-04 22.30 21.62 100.0% 3,465,167
2024-05 55.69 42.25 100.0% 4,087,103
2024-06 34.11 27.65 100.0% 4,970,234
2024-07 25.09 22.74 100.0% 5,139,716
2024-08 47.78 44.11 100.0% 5,789,394
2024-09 24.91 26.08 100.0% 4,827,626
2024-10 33.06 29.33 100.0% 4,831,241
2024-11 18.47 23.01 100.0% 3,495,104
2024-12 20.21 20.98 100.0% 3,001,129
2025-01 22.95 19.12 100.0% 3,311,790
2025-02 22.79 18.98 100.0% 3,656,364
2025-03 18.60 14.04 100.0% 5,138,950
2025-04 20.86 18.70 100.0% 5,275,562
2025-05 30.42 31.00 100.0% 6,508,623
2025-06 26.20 22.19 100.0% 6,957,597
2025-07 33.42 28.98 100.0% 7,217,379
2025-08 39.51 34.48 100.0% 7,421,005
2025-09 31.37 31.19 100.0% 6,939,612
2025-10 29.97 30.55 100.0% 6,159,690
2025-11 27.52 25.65 100.0% 4,875,312
2025-12 20.21 19.16 100.0% 4,013,625
2026-01 35.32 22.75 96.8% 4,543,845
2026-02 9.30 8.51 100.0% 5,352,788
2026-03 8.76 7.64 100.0% 6,729,090
2026-04 14.66 14.69 100.0% 5,743,260
2026-05 16.80 17.23 100.0% 7,804,637
2026-06 19.47 19.37 63.5% 4,769,073
--- HB_NORTH ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 12.00 10.97 100.0% 2,642,848
2024-03 17.73 14.27 100.0% 3,268,150
2024-04 24.49 24.53 100.0% 3,465,167
2024-05 57.00 44.44 100.0% 4,087,103
2024-06 35.73 31.60 100.0% 4,970,234
2024-07 27.01 25.94 100.0% 5,139,716
2024-08 46.47 42.54 100.0% 5,789,394
2024-09 23.76 24.74 100.0% 4,827,626
2024-10 31.70 28.85 100.0% 4,831,241
2024-11 21.37 25.39 100.0% 3,495,104
2024-12 21.52 21.29 100.0% 3,001,129
2025-01 23.66 19.90 100.0% 3,311,790
2025-02 23.59 20.60 100.0% 3,656,364
2025-03 23.77 18.59 100.0% 5,138,950
2025-04 27.67 24.87 100.0% 5,275,562
2025-05 34.67 33.56 100.0% 6,508,623
2025-06 31.29 27.97 100.0% 6,957,597
2025-07 37.56 32.80 100.0% 7,217,379
2025-08 38.76 33.15 100.0% 7,421,005
2025-09 30.21 29.95 100.0% 6,939,612
2025-10 29.34 29.89 100.0% 6,159,690
2025-11 27.14 25.46 100.0% 4,875,312
2025-12 22.56 23.43 100.0% 4,013,625
2026-01 37.43 25.83 96.8% 4,543,845
2026-02 10.72 9.05 100.0% 5,352,788
2026-03 16.07 14.55 100.0% 6,729,090
2026-04 25.36 28.90 100.0% 5,743,260
2026-05 22.52 22.59 100.0% 7,804,637
2026-06 28.77 30.52 63.5% 4,769,073
--- HB_HOUSTON ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 12.53 11.44 100.0% 2,642,848
2024-03 19.66 16.09 100.0% 3,268,150
2024-04 28.03 28.09 100.0% 3,465,167
2024-05 66.71 55.87 100.0% 4,087,103
2024-06 43.28 36.71 100.0% 4,970,234
2024-07 27.38 24.81 100.0% 5,139,716
2024-08 46.98 44.02 100.0% 5,789,394
2024-09 25.19 25.00 100.0% 4,827,626
2024-10 31.79 27.91 100.0% 4,831,241
2024-11 21.21 24.84 100.0% 3,495,104
2024-12 21.19 21.56 100.0% 3,001,129
2025-01 22.94 20.26 100.0% 3,311,790
2025-02 22.93 21.17 100.0% 3,656,364
2025-03 31.68 24.83 100.0% 5,138,950
2025-04 35.25 31.05 100.0% 5,275,562
2025-05 45.64 45.54 100.0% 6,508,623
2025-06 38.53 34.49 100.0% 6,957,597
2025-07 39.54 35.84 100.0% 7,217,379
2025-08 41.80 36.97 100.0% 7,421,005
2025-09 32.44 31.26 100.0% 6,939,612
2025-10 34.52 34.82 100.0% 6,159,690
2025-11 31.52 30.02 100.0% 4,875,312
2025-12 22.06 22.66 100.0% 4,013,625
2026-01 31.57 — 0.8% 4,543,845
2026-02 14.83 — 0.0% 5,352,788
2026-03 26.53 — 0.0% 6,729,090
2026-04 33.20 — 0.0% 5,743,260
2026-05 28.08 — 0.0% 7,804,637
2026-06 35.17 — 29.4% 4,769,073
==============================================================================================================
Solar Revenue vs Grid Price | All Available Data | 'What does owning solar actually earn?'
==============================================================================================================
Capture price = revenue-weighted avg price when generating.
Demand avg = demand-weighted grid avg (fair comparison baseline).
Value factor = capture / demand_avg. <1 = earning below market average.
Discount $K = (capture - demand_avg) x MWh -- negative = earning less than grid.
Month Gen MWh Capture $/MWh Grid Avg $/MWh Value Factor Revenue $K vs Grid $K Discount $K Neg-px hrs Sub-$20 hrs
------------------------------------------------------------------------------------------------------------------------------------------
2024-02 2,641,362 10.89 13.67 0.796 28,754 36,111 -7,357 4 390
2024-03 3,268,150 18.66 21.58 0.865 (+0.068) 60,980 70,523 -9,543 6 434
2024-04 3,465,167 26.85 25.11 1.069 (+0.205) 93,053 87,023 6,030 5 444
2024-05 4,087,103 63.43 51.90 1.222 (+0.153) 259,246 212,102 47,144 0 218
2024-06 4,970,234 43.38 35.20 1.232 (+0.010) 215,613 174,942 40,671 0 142
2024-07 5,139,716 27.60 24.55 1.124 (-0.108) 141,854 126,162 15,691 0 213
2024-08 5,789,394 46.81 38.94 1.202 (+0.078) 271,018 225,464 45,553 0 153
2024-09 4,827,626 25.14 24.68 1.019 (-0.183) 121,345 119,134 2,211 0 322
2024-10 4,831,241 33.97 30.61 1.110 (+0.091) 164,106 147,884 16,222 0 324
2024-11 3,495,104 22.21 24.43 0.909 (-0.200) 77,642 85,385 -7,743 0 289
2024-12 3,001,129 19.46 23.70 0.821 (-0.088) 58,399 71,120 -12,720 0 292
2025-01 3,311,790 22.13 30.14 0.734 (-0.087) 73,306 99,807 -26,501 8 183
2025-02 3,656,364 20.79 32.40 0.642 (-0.093) 76,030 118,448 -42,418 0 192
2025-03 5,138,950 25.71 31.46 0.817 (+0.176) 132,147 161,656 -29,509 2 159
2025-04 5,275,562 24.39 30.06 0.811 (-0.006) 128,658 158,606 -29,947 0 206
2025-05 6,508,623 31.93 34.91 0.915 (+0.103) 207,799 227,223 -19,424 0 185
2025-06 6,957,597 27.74 30.28 0.916 (+0.002) 193,013 210,709 -17,695 0 144
2025-07 7,217,379 32.14 34.07 0.943 (+0.027) 231,994 245,905 -13,911 0 113
2025-08 7,421,005 44.63 43.42 1.028 (+0.084) 331,192 322,217 8,975 0 50
2025-09 6,939,612 31.55 32.37 0.975 (-0.053) 218,928 224,624 -5,696 0 87
2025-10 6,159,690 36.60 36.76 0.996 (+0.021) 225,457 226,410 -953 0 89
2025-11 4,875,312 35.43 38.40 0.923 (-0.073) 172,754 187,215 -14,461 6 105
2025-12 4,013,625 24.57 36.51 0.673 (-0.250) 98,614 146,523 -47,909 0 139
2026-01 4,543,845 30.83 81.54 0.378 (-0.295) 140,066 370,513 -230,447 17 191
2026-02 5,352,788 11.23 19.12 0.588 (+0.210) 60,133 102,339 -42,206 26 324
2026-03 6,729,090 19.01 24.45 0.778 (+0.190) 127,938 164,514 -36,576 0 265
2026-04 5,743,260 36.04 39.59 0.910 (+0.133) 207,004 227,358 -20,355 0 111
2026-05 7,804,637 26.85 29.61 0.907 (-0.004) 209,530 231,123 -21,593 0 146
2026-06 4,769,073 30.16 31.49 0.958 (+0.051) 143,857 150,171 -6,315 0 28
--- Year-over-Year Solar Economics ---
Year TWh Capture $/MWh Grid Avg $/MWh Value Factor Revenue $M Discount to Grid $M
---------------------------------------------------------------------------------------------------
2024 45.52 32.78 29.79 1.100 1492.0 136.2
2025 67.48 30.97 34.52 0.897 2089.9 -239.4
2026 34.94 25.43 35.66 0.713 888.5 -357.5
Discount < 0 = earning LESS than buying equivalent at demand-weighted grid avg.
==============================================================================================================
DAM vs RTM Capture Price Gap | All Available Data | 'What does settling real-time actually cost?'
==============================================================================================================
DAM capture = revenue-weighted avg day-ahead price when generating.
RTM capture = revenue-weighted avg real-time price when generating.
RTM-DAM gap = negative means real-time earns less than day-ahead.
Merchant projects settling RTM eat this gap. DAM-hedged projects are insulated.
!! HB_SOUTH RTM DATA GAP -- hours below are excluded from RTM capture,
not zero-filled. An affected year's RTM number is a partial-year average,
not deflated but potentially biased toward whichever days DO have data:
2026-01: 24 hours missing RTM price
2026-06: 263 hours missing RTM price
Year Fuel DAM $/MWh RTM $/MWh RTM-DAM
-------------------------------------------------------
2024 solar 32.78 30.67 -2.11
2024 wind 22.24 21.25 -0.99
2025 solar 30.97 28.76 -2.21
2025 wind 29.49 27.34 -2.15
2026 solar 25.17 23.56 -1.61
2026 wind 29.97 26.73 -3.25
Negative RTM-DAM = real-time re-prices generation below the day-ahead clear.
Wind typically shows a larger penalty than solar (evening over-forecast re-priced down).
DAM-only value factors overstate actual merchant revenue by this gap.
==============================================================================================================
PART 2: WIND ECONOMICS TREND | Monthly Capture Price by Hub
==============================================================================================================
'Capture price' = $/MWh actually earned by ERCOT-system generation of this fuel,
priced at the named hub (a locational proxy -- see Part 7, POV note [5]).
DAM is the trend/extrapolation basis (RTM has real 2026 gaps -- Part 7, POV [3]);
RTM capture is also shown per month wherever coverage is usable (>=50% of DAM hours).
VERDICT: HB_SOUTH wind capture rose from a FITTED $21.23/MWh (2024-02) to $32.96/MWh (2026-06), trending $+5.03/MWh per year (+23.7%/yr of the 2024-02 fitted base).
(Raw single-month values were $11.92/MWh in 2024-02 and $30.02/MWh in 2026-06 -- noisier than the fit; see the table below for every month.)
NAIVE 12-MONTH EXTRAPOLATION (straight-line fit on 29 months of HB_SOUTH DAM capture, 2024-02-2026-06): $37.99/MWh.
HONESTY CAVEAT: a linear fit on a short, noisy monthly series is NOT a forecast.
It ignores mean reversion, the new-build interconnection queue, load growth, and
the RTC+B market-design change (see the DEC 2025 warning above). Read it as 'which
way the line currently points', not a number to underwrite a 50-year decision on.
--- HB_SOUTH ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 11.92 11.28 100.0% 10,973,059
2024-03 16.63 15.94 100.0% 10,158,187
2024-04 18.52 17.79 100.0% 11,618,698
2024-05 34.50 29.27 100.0% 10,149,535
2024-06 28.56 25.60 100.0% 10,000,887
2024-07 21.29 20.28 100.0% 8,104,140
2024-08 29.30 30.50 100.0% 7,652,145
2024-09 22.26 21.33 100.0% 5,948,401
2024-10 22.93 21.77 100.0% 9,465,287
2024-11 20.51 23.38 100.0% 9,945,942
2024-12 21.03 19.94 100.0% 9,192,429
2025-01 26.56 24.61 100.0% 9,603,093
2025-02 26.14 23.33 100.0% 8,949,139
2025-03 27.81 24.58 100.0% 12,029,998
2025-04 27.15 23.15 100.0% 12,232,004
2025-05 28.92 27.22 100.0% 9,295,840
2025-06 28.67 26.94 100.0% 10,589,335
2025-07 30.48 28.55 100.0% 9,184,944
2025-08 38.00 34.84 100.0% 7,123,494
2025-09 29.83 28.73 100.0% 6,757,385
2025-10 31.38 30.37 100.0% 8,927,943
2025-11 32.42 29.70 100.0% 9,962,961
2025-12 29.78 30.01 100.0% 10,125,186
2026-01 49.68 32.29 96.8% 9,665,677
2026-02 16.98 16.85 100.0% 9,487,117
2026-03 23.24 23.56 100.0% 13,305,781
2026-04 34.42 34.12 100.0% 11,457,425
2026-05 26.83 24.86 100.0% 9,646,118
2026-06 30.02 30.56 63.5% 6,168,870
--- HB_WEST ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 12.93 12.33 100.0% 10,973,059
2024-03 19.86 17.37 100.0% 10,158,187
2024-04 15.41 13.49 100.0% 11,618,698
2024-05 29.85 22.78 100.0% 10,149,535
2024-06 22.90 19.97 100.0% 10,000,887
2024-07 20.68 19.42 100.0% 8,104,140
2024-08 30.61 30.90 100.0% 7,652,145
2024-09 23.18 22.13 100.0% 5,948,401
2024-10 15.31 12.35 100.0% 9,465,287
2024-11 15.98 20.70 100.0% 9,945,942
2024-12 22.61 23.02 100.0% 9,192,429
2025-01 27.15 25.63 100.0% 9,603,093
2025-02 30.17 26.57 100.0% 8,949,139
2025-03 18.93 14.73 100.0% 12,029,998
2025-04 24.62 21.85 100.0% 12,232,004
2025-05 30.52 29.59 100.0% 9,295,840
2025-06 28.16 25.69 100.0% 10,589,335
2025-07 33.14 29.03 100.0% 9,184,944
2025-08 40.31 37.10 100.0% 7,123,494
2025-09 33.37 32.82 100.0% 6,757,385
2025-10 29.72 28.03 100.0% 8,927,943
2025-11 27.88 23.43 100.0% 9,962,961
2025-12 26.52 27.73 100.0% 10,125,186
2026-01 59.07 36.04 96.8% 9,665,677
2026-02 14.96 15.78 100.0% 9,487,117
2026-03 10.53 9.41 100.0% 13,305,781
2026-04 20.82 19.29 100.0% 11,457,425
2026-05 19.65 18.81 100.0% 9,646,118
2026-06 22.29 21.22 63.5% 6,168,870
--- HB_NORTH ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 13.03 11.62 100.0% 10,973,059
2024-03 14.28 12.64 100.0% 10,158,187
2024-04 16.43 16.31 100.0% 11,618,698
2024-05 30.80 24.39 100.0% 10,149,535
2024-06 25.12 24.71 100.0% 10,000,887
2024-07 21.46 20.98 100.0% 8,104,140
2024-08 28.48 28.61 100.0% 7,652,145
2024-09 21.42 21.34 100.0% 5,948,401
2024-10 19.38 18.37 100.0% 9,465,287
2024-11 19.66 24.11 100.0% 9,945,942
2024-12 21.60 20.07 100.0% 9,192,429
2025-01 27.49 25.80 100.0% 9,603,093
2025-02 28.88 29.07 100.0% 8,949,139
2025-03 26.20 23.65 100.0% 12,029,998
2025-04 29.75 26.46 100.0% 12,232,004
2025-05 31.02 28.29 100.0% 9,295,840
2025-06 30.10 27.44 100.0% 10,589,335
2025-07 33.22 29.38 100.0% 9,184,944
2025-08 36.24 31.76 100.0% 7,123,494
2025-09 28.75 28.83 100.0% 6,757,385
2025-10 26.80 25.54 100.0% 8,927,943
2025-11 29.16 26.57 100.0% 9,962,961
2025-12 28.55 28.72 100.0% 10,125,186
2026-01 59.23 38.51 96.8% 9,665,677
2026-02 18.76 19.86 100.0% 9,487,117
2026-03 20.46 18.53 100.0% 13,305,781
2026-04 30.50 30.71 100.0% 11,457,425
2026-05 25.89 25.41 100.0% 9,646,118
2026-06 29.70 30.65 63.5% 6,168,870
--- HB_HOUSTON ---
Month Capture DAM $/MWh Capture RTM $/MWh RTM cov % Gen MWh
------------------------------------------------------------------------
2024-02 13.61 12.30 100.0% 10,973,059
2024-03 16.74 15.68 100.0% 10,158,187
2024-04 19.42 18.95 100.0% 11,618,698
2024-05 35.58 29.99 100.0% 10,149,535
2024-06 28.59 27.10 100.0% 10,000,887
2024-07 21.84 20.50 100.0% 8,104,140
2024-08 29.05 29.51 100.0% 7,652,145
2024-09 22.28 21.90 100.0% 5,948,401
2024-10 21.97 21.10 100.0% 9,465,287
2024-11 19.86 23.30 100.0% 9,945,942
2024-12 21.85 20.69 100.0% 9,192,429
2025-01 26.92 24.52 100.0% 9,603,093
2025-02 27.89 26.76 100.0% 8,949,139
2025-03 31.17 28.29 100.0% 12,029,998
2025-04 33.89 29.90 100.0% 12,232,004
2025-05 36.65 33.82 100.0% 9,295,840
2025-06 33.43 30.67 100.0% 10,589,335
2025-07 33.76 30.78 100.0% 9,184,944
2025-08 37.26 33.60 100.0% 7,123,494
2025-09 29.79 28.63 100.0% 6,757,385
2025-10 29.86 28.41 100.0% 8,927,943
2025-11 31.08 27.99 100.0% 9,962,961
2025-12 26.60 26.15 100.0% 10,125,186
2026-01 49.99 — 0.8% 9,665,677
2026-02 19.41 — 0.0% 9,487,117
2026-03 26.62 — 0.0% 13,305,781
2026-04 34.13 — 0.0% 11,457,425
2026-05 28.54 — 0.0% 9,646,118
2026-06 32.77 — 29.4% 6,168,870
==============================================================================================================
Wind Revenue vs Grid Price | All Available Data | 'What does owning wind actually earn?'
==============================================================================================================
Capture price = revenue-weighted avg price when generating.
Demand avg = demand-weighted grid avg (fair comparison baseline).
Value factor = capture / demand_avg. <1 = earning below market average.
Discount $K = (capture - demand_avg) x MWh -- negative = earning less than grid.
Month Gen MWh Capture $/MWh Grid Avg $/MWh Value Factor Revenue $K vs Grid $K Discount $K Neg-px hrs Sub-$20 hrs
------------------------------------------------------------------------------------------------------------------------------------------
2024-02 10,889,320 11.92 13.67 0.872 129,824 148,870 -19,046 6 582
2024-03 10,158,187 16.63 21.58 0.770 (-0.102) 168,893 219,202 -50,309 6 473
2024-04 11,618,698 18.52 25.11 0.738 (-0.033) 215,216 291,787 -76,571 5 480
2024-05 10,149,535 34.50 51.90 0.665 (-0.073) 350,130 526,715 -176,585 0 349
2024-06 10,000,887 28.56 35.20 0.812 (+0.147) 285,675 352,010 -66,334 0 238
2024-07 8,104,140 21.29 24.55 0.867 (+0.056) 172,520 198,929 -26,409 0 358
2024-08 7,652,145 29.30 38.94 0.752 (-0.115) 224,234 298,008 -73,774 0 286
2024-09 5,948,401 22.26 24.68 0.902 (+0.150) 132,412 146,792 -14,380 0 342
2024-10 9,465,287 22.93 30.61 0.749 (-0.153) 217,017 289,732 -72,716 0 324
2024-11 9,945,942 20.51 24.43 0.840 (+0.091) 203,998 242,979 -38,981 0 371
2024-12 9,192,429 21.03 23.70 0.888 (+0.048) 193,358 217,839 -24,481 0 292
2025-01 9,603,093 26.56 30.14 0.881 (-0.006) 255,015 289,407 -34,393 8 189
2025-02 8,949,139 26.14 32.40 0.807 (-0.074) 233,949 289,909 -55,960 0 219
2025-03 12,029,998 27.81 31.46 0.884 (+0.077) 334,495 378,428 -43,933 2 171
2025-04 12,232,004 27.15 30.06 0.903 (+0.019) 332,073 367,746 -35,673 0 235
2025-05 9,295,840 28.92 34.91 0.828 (-0.075) 268,815 324,528 -55,713 0 198
2025-06 10,589,335 28.67 30.28 0.947 (+0.118) 303,582 320,695 -17,113 0 149
2025-07 9,184,944 30.48 34.07 0.895 (-0.052) 279,954 312,942 -32,988 0 116
2025-08 7,123,494 38.00 43.42 0.875 (-0.019) 270,715 309,299 -38,584 0 50
2025-09 6,757,385 29.83 32.37 0.922 (+0.046) 201,579 218,726 -17,147 0 99
2025-10 8,927,943 31.38 36.76 0.854 (-0.068) 280,143 328,161 -48,018 0 104
2025-11 9,962,961 32.42 38.40 0.844 (-0.009) 322,979 382,584 -59,605 6 107
2025-12 10,125,186 29.78 36.51 0.816 (-0.029) 301,506 369,633 -68,128 0 206
2026-01 9,665,677 49.68 81.54 0.609 (-0.206) 480,195 788,156 -307,961 17 270
2026-02 9,487,117 16.98 19.12 0.888 (+0.279) 161,105 181,382 -20,277 26 424
2026-03 13,305,781 23.24 24.45 0.951 (+0.062) 309,233 325,301 -16,069 0 309
2026-04 11,457,425 34.42 39.59 0.870 (-0.081) 394,415 453,565 -59,150 0 123
2026-05 9,646,118 26.83 29.61 0.906 (+0.036) 258,803 285,655 -26,852 0 171
2026-06 6,168,870 30.02 31.49 0.953 (+0.047) 185,181 194,249 -9,068 0 28
--- Year-over-Year Wind Economics ---
Year TWh Capture $/MWh Grid Avg $/MWh Value Factor Revenue $M Discount to Grid $M
---------------------------------------------------------------------------------------------------
2024 103.12 22.24 28.44 0.782 2293.3 -639.6
2025 114.78 29.49 33.91 0.870 3384.8 -507.3
2026 59.73 29.95 37.31 0.803 1788.9 -439.4
Discount < 0 = earning LESS than buying equivalent at demand-weighted grid avg.
==============================================================================================================
100 MW Merchant Revenue Model | 'What does a project actually earn?'
==============================================================================================================
Gross revenue = capture_price x project_MWh_generated.
Capacity factor (CF) = % of hours the project generates at rated capacity.
ERCOT solar CF typical range: 22-28%. Wind: 35-45%.
This is gross revenue only -- excludes O&M, debt service, interconnection, basis risk.
--- SOLAR (100 MW AC project) ---
Year Capture $/MWh Rev @20%CF $M Rev @25%CF $M Rev @28%CF $M Grid-avg Rev @25%CF Discount @25%CF $M
-----------------------------------------------------------------------------------------------------------------
2024 32.78 5.74M 7.18M 8.04M 6.52M 0.66M
2025 30.97 5.43M 6.78M 7.60M 7.56M -0.78M
2026 25.43 4.46M 5.57M 6.24M 7.81M -2.24M
--- WIND (100 MW nameplate project) ---
Year Capture $/MWh Rev @35%CF $M Rev @40%CF $M Rev @45%CF $M Grid-avg Rev @40%CF Discount @40%CF $M
-----------------------------------------------------------------------------------------------------------------
2024 22.24 6.82M 7.79M 8.77M 9.97M -2.17M
2025 29.49 9.04M 10.33M 11.62M 11.88M -1.55M
2026 29.95 9.18M 10.49M 11.81M 13.07M -2.58M
Discount = revenue captured MINUS what you'd earn at demand-weighted grid average.
Negative = project earns less than grid average for same MWh volume.
Note: these are All Available Data months only -- not full-year.
==============================================================================================================
Cannibalization Index | All Available Data
==============================================================================================================
Solar Cannibalization Index = 1 - VF_solar (% below demand-weighted grid average).
Wind Cannibalization Index = 1 - VF_wind.
Afternoon Spread = avg (Wind capture - Solar capture) in the 14:00-20:00 CT window.
Narrowing spread = solar squeezing wind's traditional premium afternoon hours.
Year Solar Discount Wind Discount PM Spread W-S Direction
---------------------------------------------------------------------------
2024 -10.0% 21.8% -23.88 Solar earns afternoon premium
2025 10.3% 13.0% -11.17 Solar earns afternoon premium Solar disc +20.3pp YoY
2026 28.7% 19.7% -3.97 Solar earns afternoon premium Solar disc +18.4pp YoY
Solar discount growing toward 40% means a 100 MW solar project earning ~60 cents
on every dollar of average-priced electricity -- and that trend shows no floor yet.
==============================================================================================================
Scarcity Revenue Dependence | All Available Data | 'How much merchant revenue comes from price spikes?'
==============================================================================================================
Revenue earned in hours where HB_SOUTH DAM price > $100/MWh, as % of total revenue.
A small % of MWh hours can carry a large % of total project revenue.
Risk: if batteries, demand response, or new thermal shave those spike hours,
project economics deteriorate even if average curtailment does not increase.
This is the 'battery cannibalizes renewable upside' mechanism -- distinct from
curtailment and from average-price cannibalization. All three erode merchant value.
Year Fuel Total MWh Spike MWh MWh % Total Rev $M Spike Rev $M Rev %
-------------------------------------------------------------------------------------------
2024 solar 45,516,226 1,346,806 3.0% 1492.0M 330.8M 22.2%
2024 wind 103,124,971 952,340 0.9% 2293.3M 232.0M 10.1%
2025 solar 67,475,509 931,450 1.4% 2089.9M 149.8M 7.2%
2025 wind 114,781,322 1,009,145 0.9% 3384.8M 155.0M 4.6%
2026 solar 34,942,693 553,768 1.6% 888.5M 106.3M 12.0%
2026 wind 59,730,988 1,035,159 1.7% 1788.9M 326.7M 18.3%
If Spike Rev % >> Spike MWh %: revenue is highly concentrated in rare high-price hours.
Stress-test: what happens to project IRR if hours above $100/MWh are capped at that level?
The answer is the scarcity-revenue term in the project's implicit price exposure.
==============================================================================================================
Value Factor Projection to 2028 | All Available Data | STRAIGHT-LINE EXTRAPOLATION ONLY
==============================================================================================================
!!! HEAVY CAVEATS -- this is a trend extrapolation, NOT a forecast. !!!
Assumes: no major new transmission, no demand response policy, no storage
mandate, no market design change. Any of these could break the trend.
Use for RISK FRAMING ('here is where we go if nothing changes'),
NOT for project underwriting or contract negotiations.
Year Solar VF (obs/proj) Wind VF (obs/proj) Solar $/MWh @$35 grid Wind $/MWh @$35 grid
----------------------------------------------------------------------------------------------------
2024 1.100 (observed) 0.782 (observed) $38.51/MWh $27.37/MWh
2025 0.897 (observed) 0.870 (observed) $31.40/MWh $30.44/MWh
2026 0.713 (observed) 0.803 (observed) $24.96/MWh $28.10/MWh
2027 0.516 (PROJECTED) 0.839 (PROJECTED) $18.07/MWh $29.37/MWh
2028 0.323 (PROJECTED) 0.849 (PROJECTED) $11.29/MWh $29.73/MWh
Solar trend: -0.1937 VF points/year. Extrapolated solar VF in 2028: 0.323
Wind trend: +0.0104 VF points/year. Extrapolated wind VF in 2028: 0.849
At a solar VF of 0.323 and $35/MWh grid avg: solar capture = $11.29/MWh.
Compare to current LCOE estimates of $25-35/MWh for new Texas solar.
The margin is thinner than it looks from nameplate economics.
==============================================================================================================
Solar vs Wind Hourly Capture Price | All Available Data | 'Is solar eating into wind profitability?'
==============================================================================================================
Capture price ($/MWh) at each hour of day, averaged across all days in season.
CT = UTC-6 (January-March standard time). S = Solar capture, W = Wind capture.
--- 2024 ---
Hr UTC CT Solar $/MWh Wind $/MWh W-S Spread Bar
---------------------------------------------------------------------------
0:00* 18:00 113.29 64.24 -49.04 SSSSSSSSSSSSSSSS
1:00* 19:00 107.03 52.70 -54.33 SSSSSSSSSSSSSSSSSS
2:00* 20:00 41.72 28.67 -13.04 SSSS
3:00 21:00 25.02 21.82 -3.21 S
4:00 22:00 18.03 18.44 +0.42
5:00 23:00 16.23 16.91 +0.68
6:00 00:00 16.65 15.30 -1.35
7:00 01:00 15.85 13.94 -1.90
8:00 02:00 14.53 13.53 -1.01
9:00 03:00 15.22 14.00 -1.23
10:00 04:00 17.50 15.73 -1.77
11:00 05:00 21.52 19.22 -2.30
12:00 06:00 18.42 20.66 +2.24
13:00 07:00 15.14 17.82 +2.68
14:00 08:00 14.29 14.31 +0.03
15:00 09:00 15.67 13.92 -1.76
16:00 10:00 17.56 14.86 -2.70
17:00 11:00 20.01 15.93 -4.08 S
18:00 12:00 23.33 17.83 -5.50 S
19:00 13:00 25.02 19.03 -5.99 S
20:00* 14:00 27.24 21.01 -6.23 SS
21:00* 15:00 31.55 24.41 -7.14 SS
22:00* 16:00 38.65 29.19 -9.46 SSS
23:00* 17:00 58.43 41.33 -17.09 SSSSS
* = wind's traditional peak earning hours (2pm-8pm CT)
--- 2025 ---
Hr UTC CT Solar $/MWh Wind $/MWh W-S Spread Bar
---------------------------------------------------------------------------
0:00* 18:00 75.39 57.46 -17.93 SSSSS
1:00* 19:00 80.30 54.59 -25.71 SSSSSSSS
2:00* 20:00 56.33 42.89 -13.44 SSSS
3:00 21:00 44.88 34.46 -10.42 SSS
4:00 22:00 33.83 29.40 -4.44 S
5:00 23:00 34.08 26.75 -7.33 SS
6:00 00:00 25.96 25.03 -0.93
7:00 01:00 24.84 23.60 -1.24
8:00 02:00 24.46 23.16 -1.30
9:00 03:00 24.90 23.70 -1.20
10:00 04:00 24.69 25.88 +1.19
11:00 05:00 31.05 29.86 -1.19
12:00 06:00 23.95 32.94 +9.00 WW
13:00 07:00 19.18 29.05 +9.87 WWW
14:00 08:00 17.59 21.30 +3.72 W
15:00 09:00 18.38 18.18 -0.19
16:00 10:00 19.79 17.65 -2.13
17:00 11:00 22.16 18.46 -3.69 S
18:00 12:00 24.81 19.77 -5.04 S
19:00 13:00 27.01 21.41 -5.61 S
20:00* 14:00 28.79 23.27 -5.52 S
21:00* 15:00 30.62 25.67 -4.95 S
22:00* 16:00 37.80 32.26 -5.54 S
23:00* 17:00 52.50 45.12 -7.38 SS
* = wind's traditional peak earning hours (2pm-8pm CT)
--- 2026 ---
Hr UTC CT Solar $/MWh Wind $/MWh W-S Spread Bar
---------------------------------------------------------------------------
0:00* 18:00 58.02 49.96 -8.06 SS
1:00* 19:00 57.70 47.54 -10.16 SSS
2:00* 20:00 48.42 44.39 -4.03 S
3:00 21:00 42.33 38.54 -3.80 S
4:00 22:00 28.50 32.91 +4.41 W
5:00 23:00 27.63 29.68 +2.05
6:00 00:00 23.57 26.56 +2.98
7:00 01:00 27.07 25.38 -1.69
8:00 02:00 22.60 25.57 +2.97
9:00 03:00 23.22 26.50 +3.28 W
10:00 04:00 25.84 29.44 +3.60 W
11:00 05:00 27.70 34.52 +6.82 WW
12:00 06:00 24.81 33.85 +9.04 WWW
13:00 07:00 19.39 31.53 +12.15 WWWW
14:00 08:00 18.23 25.44 +7.21 WW
15:00 09:00 17.76 19.14 +1.39
16:00 10:00 18.42 19.15 +0.73
17:00 11:00 18.88 18.30 -0.57
18:00 12:00 20.21 18.89 -1.32
19:00 13:00 21.55 20.03 -1.52
20:00* 14:00 22.38 21.15 -1.23
21:00* 15:00 23.60 22.79 -0.81
22:00* 16:00 26.59 26.21 -0.38
23:00* 17:00 42.79 39.61 -3.18 S
* = wind's traditional peak earning hours (2pm-8pm CT)
A narrowing W-S spread in the 14:00-20:00 CT band shows solar suppressing wind's afternoon revenues.
==============================================================================================================
PART 3: BATTERY | All Available Data
==============================================================================================================
==============================================================================================================
BATTERY (ESR) | All Available Data | ERCOT Energy Storage Resources
==============================================================================================================
Charging = grid energy absorbed by batteries (positive = charging during oversupply)
Discharging = energy released back to grid
Net = discharging - charging (negative = net absorber)
Year Charging MWh Discharge MWh Net MWh Capacity MWh Days
------------------------------------------------------------------------------
2026 3,440,591 2,808,116 -632,475 44,624,629 127
Context: battery charging vs combined solar+wind curtailment:
2026: battery charging volume (3,440,591 MWh) equaled 55.7% of combined solar+wind curtailed MWh (6,179,264 MWh).
Scale comparison only -- batteries charged during similar cheap hours, not necessarily from the same curtailed electrons.
==============================================================================================================
Battery Value Trend | HB_SOUTH | TB2/TB4 Spreads | All Available Data
==============================================================================================================
TB2 = avg(top 2 DAM hours) minus avg(bottom 2 DAM hours) per day; TB4 = same, top/bottom 4.
Standard proxy for a 2h / 4h battery's daily gross arbitrage opportunity (no losses/AS).
Month Avg TB2 $/MWh Avg TB4 $/MWh
------------------------------------------
2024-02 25.42 20.76
2024-03 54.22 41.42
2024-04 86.03 59.19
2024-05 214.25 146.94
2024-06 61.95 49.58
2024-07 33.39 25.43
2024-08 113.01 76.09
2024-09 40.89 30.13
2024-10 76.90 53.04
2024-11 48.76 36.96
2024-12 27.20 22.22
2025-01 36.89 30.93
2025-02 53.86 40.71
2025-03 58.90 47.15
2025-04 58.81 46.82
2025-05 76.83 58.42
2025-06 48.89 38.72
2025-07 59.71 46.73
2025-08 68.05 57.17
2025-09 43.98 35.92
2025-10 55.43 45.40
2025-11 61.86 51.71
2025-12 44.87 39.24
2026-01 131.25 117.25
2026-02 29.82 26.71
2026-03 38.56 33.12
2026-04 61.89 55.67
2026-05 37.82 31.65
2026-06 25.75 22.71
2026-07 39.67 33.19
TB2 trend: $-13.32/MWh per year (2024-02 to 2026-07, 30 months, naive linear fit -- same honesty caveat as Parts 1-2).
--- Top-20-Day TB2 Concentration (per year) ---
What % of a year's SUM of daily TB2 $/MWh sits in the best 20 days?
Year Sum TB2 $/MWh Top 1 day Top 5 days Top 20 days
----------------------------------------------------------------------
2024 23954.2 8.5% 20.8% 40.0%
2025 20335.4 3.0% 9.8% 21.1%
2026 10416.5 14.3% 33.3% 48.5%
High concentration = most of a battery's annual value comes from a handful of
scarcity days -- missing those days (outage, AS commitment) disproportionately hurts
realized revenue vs. this gross daily-TB potential.
==============================================================================================================
Battery Arbitrage Economics | All Available Data | 'What does the ESR fleet earn buying cheap / selling dear?'
==============================================================================================================
RTM prices: battery charges (buys) during oversupply, discharges (sells) at demand peaks.
Spread = sell price − buy price = gross energy margin per MWh throughput.
RTE = volumetric round-trip efficiency (Li-ion AC target ~85%).
Caveat: hub-level RTM, not nodal. Basis risk applies to project-level settlement.
Metric Value
------------------------------------------------
Avg charge price $ 21.28/MWh
Charge volume 3.469 TWh
Avg discharge price $ 49.07/MWh
Discharge volume 2.834 TWh
Realized spread $ +27.79/MWh
Gross energy margin $ 65.2M
Volumetric round-trip eff. 81.7%
Spread $27.79/MWh is the co-location case in one number: storage captures this
margin during low-price hours instead of letting it spill.
The 81.7% discharge/charge ratio is consistent with Li-ion AC round-trip efficiency,
but this is an aggregate SCED proxy, not a project-level measured RTE.
--- Charge / Discharge by Time-of-Day ---
Shows whether the fleet actually charges in cheap midday hours and discharges in the evening peak.
Midday charge % and Evening discharge % are the key efficiency metrics.
Window Charge MWh Chg% Buy $/MWh Discharge MWh Dis% Sell $/MWh
--------------------------------------------------------------------------------------------------
Overnight 8pm-5am CT 960,569 27.7% 33.29 743,628 26.2% 50.94
Morning 6am-9am CT 659,980 19.0% 16.44 626,339 22.1% 44.35
Midday 10am-3pm CT 1,662,723 47.9% 14.92 120,170 4.2% 21.06
Evening 4pm-7pm CT 186,118 5.4% 33.33 1,343,750 47.4% 52.74
Ideal dispatch: Midday charge % high + buy price low = buying renewable spill.
Evening discharge % high + sell price high = capturing demand-peak premium.
==============================================================================================================
PART 4: SOLAR+STORAGE COMBO | HB_SOUTH | All Available Data
==============================================================================================================
What's actually getting built now. A simple hybrid UPLIFT MODEL, not a site design:
- PV shape = ERCOT-system EIA solar generation (system-wide proxy, not a specific site).
- Battery sized at 25% of that day's peak PV MW (EDITABLE default -- no developer-quoted ratio exists for Jeff's site).
- Duration: 4h. Round-trip efficiency: 85%.
- Charge in solar hours (10:00-17:00 CENTRAL) at that day's avg DAM price there.
- Discharge into that day's top-2 non-solar-hour DAM price hours (usually evening).
- 'Solar-only $/MWh' below is the SAME PV output sold at the solar-hours avg price
(no shifting) -- so the delta isolates the value of TIME-SHIFTING, not extra sun.
REAL-WORLD CAVEAT (Jeff, 2026-07): his own site's developer is struggling to get ERCOT
battery interconnection approval, because CHARGING makes the project a LOAD (triggers a
load-interconnection study), not source-only. The numbers below are MARKET CONTEXT --
what competitors with a working combo interconnection earn -- NOT a promise Jeff's own
site can capture this. Interconnection, not economics, may be the binding constraint here
(as the plan predicted).
Month Solar-only $/MWh Hybrid $/MWh Uplift %
-------------------------------------------------------
2024-02 10.28 12.41 20.8%
2024-03 15.07 19.71 30.8%
2024-04 17.22 24.82 44.2%
2024-05 37.82 56.83 50.3%
2024-06 39.60 42.30 6.8%
2024-07 25.80 27.22 5.5%
2024-08 35.30 43.07 22.0%
2024-09 21.08 23.96 13.7%
2024-10 26.48 32.55 23.0%
2024-11 25.51 27.38 7.3%
2024-12 20.58 22.07 7.2%
2025-01 22.16 25.58 15.5%
2025-02 19.62 25.32 29.0%
2025-03 20.39 25.56 25.3%
2025-04 18.05 22.99 27.3%
2025-05 23.79 29.77 25.2%
2025-06 23.01 26.34 14.5%
2025-07 26.59 30.98 16.5%
2025-08 39.51 43.36 9.8%
2025-09 28.07 30.76 9.6%
2025-10 32.90 36.39 10.6%
2025-11 39.62 41.76 5.4%
2025-12 25.71 29.03 12.9%
2026-01 30.39 43.29 42.5%
2026-02 10.54 13.07 24.0%
2026-03 14.59 17.83 22.2%
2026-04 29.59 34.45 16.4%
2026-05 23.41 25.84 10.4%
2026-06 27.84 29.17 4.8%
Avg monthly uplift: +19.1% (range +4.8% to +50.3%).
==============================================================================================================
PART 5: CURTAILMENT | All Available Data
==============================================================================================================
==============================================================================================================
SOLAR | All Available Data | Year-over-Year
==============================================================================================================
Year Total Curt MWh Avg/Day MWh Median/Day Curt Rate Max Day MWh Max Date Curt Days Heavy Days
------------------------------------------------------------------------------------------------------------------
2024 2,851,863 8,539 2,859 5.90% 63,830 2024-04-13 334 81
2025 4,206,333 11,588 6,067 5.87% 87,326 2025-04-12 363 121 (+47.5% YoY)
2026 2,763,183 21,587 12,576 10.31% 110,804 2026-02-24 127 66 (-34.3% YoY)
Generation (Base Point dispatch — proxy for actual output):
Year Avg Daily Dispatched MWh Avg Daily Available MWh Dispatch Rate
--------------------------------------------------------------------------
2024 136,312 144,801 94.14%
2025 185,762 197,243 94.18%
2026 187,762 209,317 89.70%
==============================================================================================================
WIND | All Available Data | Year-over-Year
==============================================================================================================
Year Total Curt MWh Avg/Day MWh Median/Day Curt Rate Max Day MWh Max Date Curt Days Heavy Days
------------------------------------------------------------------------------------------------------------------
2024 4,954,021 14,832 6,945 4.59% 113,152 2024-03-24 334 143
2025 5,743,242 15,822 6,008 4.76% 137,334 2025-03-18 363 147 (+15.9% YoY)
2026 3,416,081 26,688 18,589 7.00% 105,740 2026-04-13 128 84 (-40.5% YoY)
Generation (Base Point dispatch — proxy for actual output):
Year Avg Daily Dispatched MWh Avg Daily Available MWh Dispatch Rate
--------------------------------------------------------------------------
2024 308,228 322,943 95.44%
2025 316,532 332,251 95.27%
2026 354,720 381,328 93.02%
==============================================================================================================
SOLAR | Monthly Breakdown
==============================================================================================================
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
--------------------------------------------------------------------------------------------------------------
2024 — 330,562(11.1%) 311,340( 8.7%) 638,265(15.5%) 239,232( 5.6%) 243,843( 4.7%) 146,875( 2.8%) 55,727( 1.0%) 120,801( 2.4%) 338,188( 6.5%) 215,645( 5.8%) 211,386( 6.6%)
2025 350,679(10.0%) 255,196( 6.5%) 869,037(14.4%) 571,944( 9.8%) 340,629( 5.0%) 384,874( 5.3%) 204,336( 2.8%) 86,198( 1.1%) 215,719( 3.0%) 419,239( 6.4%) 295,496( 5.7%) 212,986( 5.0%)
2026 422,207( 8.7%) 718,250(11.6%) 1,004,036(13.1%) 485,719( 9.8%) 132,972( 4.2%) — — — — — — —
Values = Total MWh curtailed (curtailment rate %)
==============================================================================================================
WIND | Monthly Breakdown
==============================================================================================================
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
--------------------------------------------------------------------------------------------------------------
2024 — 681,681( 5.9%) 763,893( 7.0%) 1,039,447( 8.2%) 389,510( 3.9%) 328,138( 3.2%) 71,584( 0.9%) 31,982( 0.4%) 76,651( 1.3%) 548,520( 5.5%) 679,786( 6.4%) 342,829( 3.6%)
2025 488,386( 5.0%) 375,158( 4.0%) 1,104,580( 8.4%) 1,078,854( 8.1%) 467,577( 4.8%) 380,694( 3.5%) 148,574( 1.6%) 65,893( 0.9%) 50,782( 0.7%) 358,878( 3.8%) 549,066( 5.2%) 674,800( 6.2%)
2026 675,392( 6.6%) 660,254( 6.4%) 1,195,614( 8.3%) 742,374( 7.6%) 142,446( 3.4%) — — — — — — —
Values = Total MWh curtailed (curtailment rate %)
==============================================================================================================
EIA Grid Mix | All Available Data | Source: EIA Hourly Electric Grid Monitor
==============================================================================================================
All values MWh. Timestamps UTC. ERCO balancing authority.
--- EIA Totals Over Available Months ---
Year Demand TWh Wind TWh Solar TWh Gas TWh Coal TWh Nuc TWh RE % Gas % RE TWh
------------------------------------------------------------------------------------------------------
2024 425.48 103.21 45.52 186.57 52.66 35.43 35.0% 43.8% 148.73
2025 488.04 114.78 67.48 199.63 63.22 41.94 37.3% 40.9% 182.26 (RE: +2.4pp YoY)
2026 219.82 59.73 34.94 80.69 26.02 18.72 43.1% 36.7% 94.67 (RE: +5.7pp YoY)
--- Monthly Renewable Penetration vs Curtailment ---
Month Demand MWh Wind MWh Solar MWh RE % Gas % Curt MWh Curt/RE %
------------------------------------------------------------------------------------------
2024-02 30,719,945 10,973,059 2,642,848 44.3% 33.3% 1,012,244 7.4%
2024-03 32,445,165 10,158,187 3,268,150 41.4% 39.4% 1,075,233 8.0%
2024-04 33,582,123 11,618,698 3,465,167 44.9% 36.2% 1,677,713 11.1%
2024-05 40,180,888 10,149,535 4,087,103 35.4% 45.9% 628,741 4.4%
2024-06 44,585,457 10,000,887 4,970,234 33.6% 46.7% 571,981 3.8%
2024-07 44,789,214 8,104,140 5,139,716 29.6% 48.8% 218,459 1.6%
2024-08 49,569,648 7,652,145 5,789,394 27.1% 52.0% 87,709 0.7%
2024-09 41,270,092 5,948,401 4,827,626 26.1% 49.9% 197,452 1.8%
2024-10 39,612,493 9,465,287 4,831,241 36.1% 43.7% 886,708 6.2%
2024-11 33,838,530 9,945,942 3,495,104 39.7% 38.8% 895,431 6.7%
2024-12 34,889,133 9,192,429 3,001,129 34.9% 38.5% 554,215 4.5%
2025-01 40,431,522 9,603,093 3,311,790 31.9% 42.5% 839,064 6.5%
2025-02 34,647,600 8,949,139 3,656,364 36.4% 40.0% 630,355 5.0%
2025-03 34,710,083 12,029,998 5,138,950 49.5% 27.6% 1,973,616 11.5%
2025-04 36,521,300 12,232,004 5,275,562 47.9% 31.5% 1,650,798 9.4%
2025-05 41,155,394 9,295,840 6,508,623 38.4% 42.1% 808,206 5.1%
2025-06 45,146,143 10,589,335 6,957,597 38.9% 40.8% 765,569 4.4%
2025-07 47,791,469 9,184,944 7,217,379 34.3% 45.0% 352,909 2.2%
2025-08 49,484,422 7,123,494 7,421,005 29.4% 50.3% 152,091 1.0%
2025-09 43,971,394 6,757,385 6,939,612 31.1% 47.4% 266,501 1.9%
2025-10 41,072,528 8,927,943 6,159,690 36.7% 42.8% 778,117 5.2%
2025-11 35,451,702 9,962,961 4,875,312 41.9% 36.1% 844,563 5.7%
2025-12 37,651,867 10,125,186 4,013,625 37.6% 37.6% 887,785 6.3%
2026-01 39,716,906 9,665,677 4,543,845 35.8% 41.1% 1,097,599 7.7%
2026-02 33,229,072 9,487,117 5,352,788 44.7% 31.8% 1,378,504 9.3%
2026-03 37,914,647 13,305,781 6,729,090 52.8% 27.9% 2,199,650 11.0%
2026-04 37,941,549 11,457,425 5,743,260 45.3% 35.2% 1,228,093 7.1%
2026-05 41,759,413 9,646,118 7,804,637 41.8% 41.0% 275,417 1.6%
2026-06 29,262,124 6,168,870 4,769,073 37.4% 43.7% 0 0.0%
Curt/RE % = curtailed MWh as % of total renewable generation that month.
==============================================================================================================
Net-Load Belly Depth | All Available Data | Leading Indicator of Forced Curtailment
==============================================================================================================
Net load = Demand - Wind - Solar (MWh/hr).
When this approaches zero or goes negative, the grid has more renewable supply
than load -- curtailment becomes physically forced, not just economic.
Monthly minimum and hours below threshold are the early-warning gauges.
Watch for the minimum to trend toward zero as solar capacity grows.
Month Min Net Load Avg Net Load Hrs < 25GW Hrs < 20GW Hrs < 15GW
------------------------------------------------------------------------------
2024-02 12,405 24,575 429 235 59 << WATCH
2024-03 11,125 25,563 368 212 54 << WATCH
2024-04 11,953 25,692 352 171 49 << WATCH
2024-05 19,049 34,871 62 5 0 < warning
2024-06 22,634 41,131 6 0 0
2024-07 26,310 42,400 0 0 0
2024-08 29,394 48,559 0 0 0
2024-09 23,097 42,353 6 0 0
2024-10 14,742 34,027 154 48 5 << WATCH
2024-11 10,628 28,330 286 121 28 << WATCH
2024-12 14,154 30,505 219 86 5 << WATCH
2025-01 13,372 36,985 134 63 6 << WATCH
2025-02 12,442 32,801 211 131 28 << WATCH
2025-03 9,586 23,577 454 262 111 << WATCH
2025-04 10,230 26,408 329 155 42 << WATCH
2025-05 10,836 34,074 122 57 7 << WATCH
2025-06 18,020 38,332 23 6 0 < warning
2025-07 19,252 42,190 19 1 0 < warning
2025-08 23,771 46,962 3 0 0
2025-09 18,762 42,048 18 2 0 < warning
2025-10 10,167 34,926 111 54 15 << WATCH
2025-11 9,812 28,630 283 133 42 << WATCH
2025-12 10,397 31,604 218 88 31 << WATCH
2026-01 12,101 34,284 194 104 26 << WATCH
2026-02 8,826 27,365 311 191 72 << WATCH
2026-03 6,978 24,032 436 238 103 << WATCH
2026-04 9,278 28,807 231 78 31 << WATCH
2026-05 7,956 32,673 148 60 30 << WATCH
2026-06 22,018 40,185 13 0 0
Interpretation: hours below 20 GW net load are when curtailment is most likely forced.
As ERCOT adds solar, the minimum net load decreases and those hours multiply.
The month when minimum net load approaches zero is when the grid saturates.
This metric predicts next year's curtailment before it happens.
==============================================================================================================
Net-Load Saturation Index | All Available Data | 'How concentrated is curtailment in belly hours?'
==============================================================================================================
Net load = Demand − Wind − Solar (MWh/hr). Threshold: < 20 GW = belly hour.
Saturation Index = curtailment during belly hours ÷ total curtailment.
A RISING index with FLAT belly-hour share means each belly hour is getting worse,
not just more frequent -- the grid's absorption limit is the binding constraint.
Full-year data (not season-filtered) so index is comparable across years.
Year Total Hrs Belly Hrs Belly % Belly Curt MWh Total Curt MWh Saturation Idx
---------------------------------------------------------------------------------------------
2024 8,040 878 10.9% 2,940,019 7,807,738 37.7%
2025 8,760 952 10.9% 4,304,597 9,948,025 43.3%
2026 4,080 671 16.4% 3,495,242 6,147,959 56.9%
Rising saturation index = curtailment is concentrating in belly hours faster
than belly hours are multiplying. The 'bad hours' are getting disproportionately worse.
This is the structural shift: not just 'more curtailment' but 'same hours, much worse'.
==============================================================================================================
Grid Context on Top Curtailment Days | All Available Data
==============================================================================================================
EIA hourly data (Central day, matching the curtailment day). RE = Wind + Solar.
Rank Date Curt MWh Demand Wind Solar Gas RE % Gas % RE - Curt MWh
---------------------------------------------------------------------------------------------------------
1 2026-02-24 214,030 1,208,780 573,753 148,517 227,211 59.8% 18.8% 508,240
2 2025-03-18 206,924 1,140,806 571,225 145,111 168,560 62.8% 14.8% 509,412
3 2025-03-17 182,832 1,112,513 518,694 149,124 205,178 60.0% 18.4% 484,986
4 2025-01-05 181,674 1,123,778 539,348 53,398 288,221 52.7% 25.6% 411,072
5 2026-03-26 168,648 1,317,557 567,678 212,956 304,841 59.2% 23.1% 611,986
6 2025-03-19 168,444 1,114,020 517,239 139,659 210,893 59.0% 18.9% 488,454
7 2024-10-29 163,092 1,350,826 597,993 72,324 439,508 49.6% 32.5% 507,225
8 2025-10-29 162,505 1,105,940 489,150 145,456 278,588 57.4% 25.2% 472,101
9 2026-03-29 160,159 1,173,152 503,789 202,133 264,312 60.2% 22.5% 545,763
10 2026-03-22 158,410 1,253,424 540,185 244,278 268,454 62.6% 21.4% 626,053
RE - Curt = renewable energy that actually reached consumers after curtailment losses.
==============================================================================================================
Curtailment Driver Analysis | All Available Data
==============================================================================================================
Gas % < 15% = OVERSUPPLY: demand was low, everything dispatchable was backed off.
Gas % > 25% = CONGESTION/MUST-RUN: thermal still running despite RE being curtailed.
Suggests transmission constraints or minimum-stable-generation floors.
Mixed (15-25%) = combination of both.
Rank Date Curt MWh Demand Wind Solar Gas Gas% Driver
--------------------------------------------------------------------------------------------
1 2026-02-24 214,030 1,208,780 573,753 148,517 227,211 18.8% Mixed
2 2025-03-18 206,924 1,140,806 571,225 145,111 168,560 14.8% Oversupply -- demand too low
3 2025-03-17 182,832 1,112,513 518,694 149,124 205,178 18.4% Mixed
4 2025-01-05 181,674 1,123,778 539,348 53,398 288,221 25.6% Congestion / must-run thermal
5 2026-03-26 168,648 1,317,557 567,678 212,956 304,841 23.1% Mixed
6 2025-03-19 168,444 1,114,020 517,239 139,659 210,893 18.9% Mixed
7 2024-10-29 163,092 1,350,826 597,993 72,324 439,508 32.5% Congestion / must-run thermal
8 2025-10-29 162,505 1,105,940 489,150 145,456 278,588 25.2% Congestion / must-run thermal
9 2026-03-29 160,159 1,173,152 503,789 202,133 264,312 22.5% Mixed
10 2026-03-22 158,410 1,253,424 540,185 244,278 268,454 21.4% Mixed
Policy note: congestion-driven curtailment requires transmission investment;
oversupply-driven curtailment responds to demand response, storage, or exports.
==============================================================================================================
Curtailment Driver Summary | All Available Data | All Significant Days (>5 GWh)
==============================================================================================================
Classifies ALL days with >5 GWh combined solar+wind curtailment (not just top-10).
Gas% < 15% = OVERSUPPLY: demand low, thermal backed off. Fix: storage / demand response.
Gas% > 25% = CONGESTION: thermal still running despite curtailment. Fix: transmission.
15-25% = MIXED. These two causes need different policy responses.
Year Sig Days Oversupply % Mixed % Congestion % MWh (OS) MWh (CG)
---------------------------------------------------------------------------------------------------
2024 223 0 0% 24 11% 199 89% 0 5,695,806
2025 290 1 0% 32 11% 257 89% 206,924 6,522,020
2026 104 0 0% 17 16% 87 84% 0 4,346,523
Oversupply-driven curtailment responds to storage and demand response.
Congestion-driven curtailment primarily requires transmission or local load.
Co-located storage can reduce curtailment only if it charges behind the constraint
and discharges when the constraint relaxes -- it does not solve a chronically
export-constrained area by itself.
==============================================================================================================
Generation Price-Bucket Exposure | All Available Data
==============================================================================================================
% of actual generation occurring in each HB_SOUTH DAM price tier.
Shows whether solar/wind is earning in good hours or trash hours.
Average capture price hides this distribution.
Year Fuel < $0 $0-20 $20-50 $50-100 > $100
--------------------------------------------------------------------------
2024 solar 0.1% 42.3% 45.6% 9.1% 3.0%
2024 wind 0.4% 60.6% 34.7% 3.4% 0.9%
2025 solar 0.2% 33.0% 54.3% 11.1% 1.4%
2025 wind 0.3% 25.0% 65.6% 8.2% 0.9%
2026 solar 2.2% 46.5% 44.5% 5.2% 1.6%
2026 wind 1.3% 34.6% 57.6% 4.7% 1.7%
Negative-price generation % growing in 2026 = more generation occurring during
grid oversupply. These hours drive the capture price collapse.
==============================================================================================================
Curtailment Price-Bucket Exposure | All Available Data
==============================================================================================================
% of curtailed MWh occurring in each price tier.
Key finding: most curtailment happens at POSITIVE prices, not negative.
This implicates transmission congestion / local constraints, not just oversupply.
Year Fuel < $0 $0-20 $20-50 $50-100 > $100 Positive-px %
--------------------------------------------------------------------------
2024 solar 1.3% 69.4% 26.7% 2.0% 0.7% 98.7%
2024 wind 1.8% 68.6% 26.4% 2.6% 0.7% 98.2%
2025 solar 2.2% 62.8% 31.5% 3.3% 0.2% 97.8%
2025 wind 1.6% 44.2% 47.5% 5.9% 0.7% 98.4%
2026 solar 12.0% 67.6% 18.5% 0.9% 1.0% 88.0%
2026 wind 6.1% 53.2% 38.0% 1.7% 1.0% 93.9%
'Curtailed while price was positive' is the congestion fingerprint:
the market wanted the energy but the grid couldn't physically move it.
==============================================================================================================
Lost Hub-Value of Curtailed Energy | All Available Data
==============================================================================================================
Approximate lost merchant revenue = curtailed_MWh x HB_SOUTH_DAM_price.
!!! CAVEAT: hub price != nodal settlement price. West Texas projects
often receive significantly less than the hub price due to basis.
Use as 'scale of pain,' not as contract or litigation-grade valuation.
Year Solar lost $M Wind lost $M Combined $M $/MWh lost
----------------------------------------------------------------
2024 50.3M 89.3M 139.6M $17.88/MWh avg hub px of curtailed hours
2025 74.1M 137.2M 211.2M $21.23/MWh avg hub px of curtailed hours
2026 37.4M 72.1M 109.5M $17.81/MWh avg hub px of curtailed hours
Note: these are All Available Data months only. Full-year losses will be larger.
==============================================================================================================
Economic Curtailment Reframe | All Available Data | Voluntary vs Involuntary
==============================================================================================================
NOT all curtailment is grid oppression. Two fundamentally different causes:
VOLUNTARY (negative-price hours): the market price is negative -- the plant
is economically correct to curtail. No revenue was lost; generating would have
cost the owner money. This is the market working as designed.
INVOLUNTARY (positive-price hours): the grid wanted the energy but could not
move it due to transmission constraints or dispatch limits. REAL revenue foregone.
This is the actual grid problem -- and it dominates the numbers.
The MWh headline treats both equally. The economic framing does not.
Year Total curt MWh @ neg price MWh Neg % Net $M lost @ pos price MWh Pos % Pos $M lost Note
--------------------------------------------------------------------------------------------------------------
2024 7,807,738 124,694 1.6% -0.1M 7,683,043 98.4% 139.7M Mostly congestion-driven
2025 9,948,025 188,144 1.9% -0.2M 9,759,881 98.1% 211.4M Mostly congestion-driven
2026 6,147,959 537,048 8.7% -1.1M 5,610,911 91.3% 110.6M Market worked
Key reframe: the positive-price MWh (right column) are the real loss.
Negative-price MWh (left) = voluntary; no revenue was ever available.
The 'curtailment crisis' narrative should cite positive-price curtailment only.
Source: SCED curtailment (normalized) x HB_SOUTH DAM price. Hub-level only.
==============================================================================================================
Pain Stack: Cannibalization vs Curtailment Loss | All Available Data | 'Which one is actually killing merchant revenue?'
==============================================================================================================
TWO DIFFERENT REVENUE PROBLEMS -- they require different fixes:
GROSS DOWNSIDE $M = max(0, grid_avg − capture) × MWh (downside-only; ignores premium months)
Counts only months where capture < grid avg. Premium months do not offset this column.
When VF > 1.0 in some months, gross downside and net will point in opposite directions.
NET DISC/PREM $M = (capture − grid_avg) × MWh (full-year net; + = premium, − = discount)
The true net position. Use this for headline economics; gross downside for tail-risk.
CURTAILMENT PAIN $M = curtailed_MWh × HB_SOUTH_DAM_price (hub proxy, not nodal).
Negative-price curtailment hours reduce this total.
Pain Ratio = Gross Downside ÷ Curtailment Pain. > 1 = cannibalization bigger problem.
CAVEAT: Net/Gross use EIA data (reliable). Curtailment uses hub price (proxy).
Year Fuel Gross Down $M Net Disc/Prem $M Curtail. $M Pain Ratio Story
----------------------------------------------------------------------------------------------------
2024 solar 37.4M +136.2M 50.3M 0.7× Curtailment dominates this year
2024 wind 639.6M -639.6M 89.3M 7.2× Cannibalization dominates strongly
2025 solar 248.4M -239.4M 74.0M 3.4× Cannibalization >> curtailment
2025 wind 507.2M -507.2M 137.2M 3.7× Cannibalization >> curtailment
2026 solar 357.5M -357.5M 37.4M 9.6× Curtailment is noise vs cannibalization
2026 wind 439.4M -439.4M 72.1M 6.1× Cannibalization dominates strongly
When Gross Downside and Net point in opposite directions (e.g. 2024 solar), VF > 1
that year: premium months outweighed discount months in aggregate, but the gross
downside still shows the tail-risk exposure in the worst sub-periods.
Use Net for project underwriting; Gross Downside for stress-testing.
==============================================================================================================
Top-Day Concentration Risk | All Available Data
==============================================================================================================
What % of seasonal curtailment is driven by the worst few days?
High concentration = a few catastrophic days dominate; chronic = spread evenly.
2026 showing higher concentration = fewer, bigger events.
Year Total MWh Top 1 day Top 5 days Top 10 days Top 20 days Days to 50%
------------------------------------------------------------------------------------------
2024 7,805,884 2.1% 9.7% 17.8% 30.7% 42 days
2025 9,949,575 2.1% 9.1% 16.1% 27.3% 47 days
2026 6,179,264 3.5% 13.8% 25.2% 44.0% 24 days
Fewer days driving more curtailment = episodic / weather-driven.
More days needed for 50% = chronic structural oversupply.
==============================================================================================================
Seasonal Danger Score | All Quarters
==============================================================================================================
Danger Score = curtailment_rate(%) x (1 - solar_VF).
Combines physical curtailment waste with price cannibalization into one number.
Q3 (summer) is the safe harbor: low curtailment + decent VF.
Q1/Q2 spring: high curtailment + deteriorating VF = double penalty.
Higher = worse for project economics.
Year Q1 Jan-Mar Q2 Apr-Jun Q3 Jul-Sep Q4 Oct-Dec
----------------------------------------------------------------------
2024 1.03 (7.2%×0.14) -1.19 (6.2%×-0.19) -0.18 (1.3%×-0.14) -0.01 (5.5%×-0.00)
2025 1.92 (7.5%×0.26) 0.66 (6.0%×0.11) 0.03 (1.7%×0.02) 0.60 (5.4%×0.11)
2026 4.75 (8.7%×0.54) 0.60 (6.8%×0.09) — —
Score interpretation: < 1 = manageable, 1-3 = significant risk, > 3 = severe.
==============================================================================================================
RE Penetration vs Curtailment Rate | All Available Data
==============================================================================================================
Groups months by renewable (WND+SUN) % of demand, shows avg curtailment rate.
The non-linear steepening above ~45% is the grid's 'absorption capacity' limit.
Curtailment rate = (solar+wind curtailed) / (solar+wind available). Valid metric.
RE Penetration Months Avg Curt Rate Min Curt Max Curt Bar
--------------------------------------------------------------------------------
< 30% RE 4 1.3% 0.7% 1.8% ||
30-37% RE 10 4.5% 1.9% 7.3% |||||||||
37-42% RE 7 5.4% 3.7% 7.4% ||||||||||
42-47% RE 4 8.4% 6.9% 10.0% ||||||||||||||||
47-52% RE 2 9.4% 8.6% 10.3% ||||||||||||||||||
> 52% RE 1 10.0% 10.0% 10.0% |||||||||||||||||||
Pearson r = 0.877 R² = 0.769 (strong positive correlation)
Implication: curtailment is not evenly distributed -- it concentrates in
high-RE months, and the rate accelerates as penetration exceeds 45-50%.
==============================================================================================================
Curtailment Heatmap (Rate) | All Available Data
==============================================================================================================
Each cell = curtailment rate (%) by UTC hour. CT = UTC-6 (winter) / UTC-5 (spring).
.=<2% :=2-6% +=6-12% *=12-20% #=>20%
Solar hours peak around 12-22 UTC (7am-5pm CT). Wind peak: 00-06 UTC (6pm-midnight CT).
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
------------------------------------------------------------------------------------
2024-02 : : : : : + + + + + : : : : : : + + + + + + + +
2024-03 : : + + + + + + + + + + + : : + + + + + + + + :
2024-04 + + + + + + + + + + + + + + + * * * * * * + * +
2024-05 : : : : : : : : : : . . . : : : : : : : : + + +
2024-06 : : : . : : : : . . . . . : : : : : : : : : : :
2024-07 . . . . . . . . . . . . . . : : : : : . : . . .
2024-08 . . . . . . . . . . . . . . . . . . . . . . . .
2024-09 . . . . . . . . . . . . . . . : : : . . : : : .
2024-10 : : : : : + + + + : : : : : : + + + + + + + : :
2024-11 : + + + + + + + + : : : : : + + + + + + + + : :
2024-12 . . : : : : : : : : : : : : : : : : + + + + : .
2025-01 : : : : : : : : : : : : : : : : + + + + + * + :
2025-02 . : : : : : : : : : : : : : : : : : : + + + + :
2025-03 + : : + + + + + + + + : : + + * * * * * * * * +
2025-04 + + + + + + + + + + + : : + + + + + + + + + + +
2025-05 : : : : : : : : : : : : : : : + + + : : : + + :
2025-06 : . . . . . . . . . . . : : : : : : : + + + + :
2025-07 : . . . . . . . . . . . . . : : : : . : : : : :
2025-08 . . . . . . . . . . . . . . . . . . . . . . . .
2025-09 . . . . . . . . . . . . . . : : : : : : : : : :
2025-10 . : : : : : : : : : : : : : : + + + + + + + : :
2025-11 : : : : : : : : : : : : : : : + + + + + + + : :
2025-12 : : : : : : : : : : : : : : : + + + + + + + : :
2026-01 : : : : : : : : : : : : : : : + + + + + * * + :
2026-02 : : : : : : : : : : : : : : : + + + * * * * * +
2026-03 + : : : : + + + + : : : : + + * * * * * * * * +
2026-04 + : : : : : : : : : : : : : + + + + + + + + + +
2026-05 : . . . : . . . . . . . . : : + : : : : : : : :
High-rate cells (*, #) show when curtailment is most severe.
Compare rows across years to see whether curtailment is spreading into new hours.
==============================================================================================================
Monthly Peaks | All Available Data | Gen & Curtailment
==============================================================================================================
Prices = avg HB_SOUTH DAM price on that specific day.
Generation = total dispatched MWh (normalized). Curtailment = MWh lost (HSL - Base Point, normalized).
--- GENERATION PEAKS (biggest dispatch day per month) ---
Month Solar Peak Date Solar MWh Price Wind Peak Date Wind MWh Price
-----------------------------------------------------------------------------------------------
2024-02 2024-02-19 153,220 $ 15.26 2024-02-04 561,333 $ 8.03
2024-03 2024-03-26 174,850 $ 26.01 2024-03-29 605,956 $ 5.11
2024-04 2024-04-04 192,066 $ 18.57 2024-04-05 586,623 $ 7.64
2024-05 2024-05-18 199,350 $ 29.45 2024-05-15 504,431 $ 20.18
2024-06 2024-06-23 209,762 $ 46.14 2024-06-18 585,712 $ 25.13
2024-07 2024-07-16 207,937 $ 24.38 2024-07-31 524,471 $ 14.86
2024-08 2024-08-18 209,596 $ 39.09 2024-08-12 385,096 $ 25.18
2024-09 2024-09-09 205,547 $ 16.18 2024-09-21 404,758 $ 19.53
2024-10 2024-10-02 190,666 $ 29.99 2024-10-29 602,405 $ 21.84
2024-11 2024-11-20 165,953 $ 23.23 2024-11-24 566,981 $ 13.84
2024-12 2024-12-21 149,635 $ 24.17 2024-12-12 550,844 $ 19.35
2025-01 2025-01-19 174,046 $ 36.76 2025-01-17 580,805 $ 17.32
2025-02 2025-02-28 216,293 $ 26.94 2025-02-17 523,810 $ 18.96
2025-03 2025-03-20 252,919 $ 35.34 2025-03-06 615,046 $ 21.29
2025-04 2025-04-10 268,050 $ 31.46 2025-04-05 594,851 $ 27.37
2025-05 2025-05-12 280,945 $ 30.44 2025-05-24 538,892 $ 25.78
2025-06 2025-06-16 275,093 $ 32.93 2025-06-22 599,070 $ 23.96
2025-07 2025-07-29 304,616 $ 38.21 2025-07-20 526,592 $ 24.46
2025-08 2025-08-06 287,073 $ 27.39 2025-08-09 445,243 $ 26.78
2025-09 2025-09-09 284,970 $ 22.38 2025-09-13 382,454 $ 26.43
2025-10 2025-10-19 248,873 $ 23.51 2025-10-28 486,341 $ 34.78
2025-11 2025-11-10 224,487 $ 40.79 2025-11-28 567,827 $ 20.13
2025-12 2025-12-31 209,618 $ 28.25 2025-12-27 540,871 $ 12.32
2026-01 2026-01-31 244,727 $ 53.07 2026-01-08 510,728 $ 11.92
2026-02 2026-02-06 254,676 $ 20.32 2026-02-24 579,403 $ 10.73
2026-03 2026-03-21 316,118 $ 24.09 2026-03-15 579,193 $ 21.11
2026-04 2026-04-06 322,538 $ 31.73 2026-04-03 554,870 $ 28.04
2026-05 2026-05-13 368,977 $ 27.30 2026-05-17 599,455 $ 18.75
--- CURTAILMENT PEAKS (worst curtailment day per month) ---
Month Solar Curt Date Solar MWh Price Wind Curt Date Wind MWh Price
-----------------------------------------------------------------------------------------------
2024-02 2024-02-04 52,180 $ 8.03 2024-02-21 74,533 $ 3.82
2024-03 2024-03-24 44,422 $ 6.02 2024-03-24 113,152 $ 6.02
2024-04 2024-04-13 63,830 $ 9.98 2024-04-06 90,659 $ 6.91
2024-05 2024-05-19 60,238 $ 21.66 2024-05-19 44,456 $ 21.66
2024-06 2024-06-17 60,228 $ 26.31 2024-06-17 62,593 $ 26.31
2024-07 2024-07-01 32,793 $ 25.89 2024-07-31 11,948 $ 14.86
2024-08 2024-08-11 5,836 $ 23.41 2024-08-08 3,019 $ 30.49
2024-09 2024-09-30 15,884 $ 31.03 2024-09-08 18,569 $ 12.04
2024-10 2024-10-28 55,028 $ 23.33 2024-10-29 112,254 $ 21.84
2024-11 2024-11-18 31,880 $ 21.57 2024-11-24 83,467 $ 13.84
2024-12 2024-12-30 57,772 $ 13.81 2024-12-30 58,745 $ 13.81
2025-01 2025-01-05 71,061 $ 6.50 2025-01-05 110,613 $ 6.50
2025-02 2025-02-26 50,229 $ 16.64 2025-02-26 46,180 $ 16.64
2025-03 2025-03-19 80,680 $ 23.04 2025-03-18 137,334 $ 22.27
2025-04 2025-04-12 87,326 $ 18.84 2025-04-01 93,381 $ 28.13
2025-05 2025-05-04 41,341 $ 16.35 2025-05-14 69,810 $ 44.74
2025-06 2025-06-20 52,026 $ 26.09 2025-06-21 72,835 $ 22.26
2025-07 2025-07-27 14,411 $ 25.79 2025-07-12 14,813 $ 29.16
2025-08 2025-08-14 8,523 $ 37.68 2025-08-08 5,845 $ 33.26
2025-09 2025-09-28 14,939 $ 25.95 2025-09-24 5,785 $ 30.51
2025-10 2025-10-29 81,724 $ 16.97 2025-10-29 80,782 $ 16.97
2025-11 2025-11-09 77,758 $ 21.73 2025-11-29 68,093 $ 26.06
2025-12 2025-12-19 33,764 $ 22.33 2025-12-19 76,915 $ 22.33
2026-01 2026-01-14 61,775 $ 14.45 2026-01-08 81,669 $ 11.92
2026-02 2026-02-24 110,804 $ 10.73 2026-02-24 103,225 $ 10.73
2026-03 2026-03-29 93,048 $ 21.40 2026-03-26 93,999 $ 29.14
2026-04 2026-04-09 53,545 $ 28.13 2026-04-13 105,740 $ 25.84
2026-05 2026-05-03 67,243 $ 20.39 2026-05-17 45,669 $ 18.75
==============================================================================================================
Top 20 Curtailment Days | All Available Data
==============================================================================================================
Rank Date Combined MWh Solar MWh Wind MWh Solar % Wind %
-------------------------------------------------------------------------------------
1 2026-02-24 214,030 110,804 103,225 23.58% 21.96%
2 2025-03-18 206,924 69,589 137,334 15.06% 29.73%
3 2025-03-17 182,832 80,633 102,199 18.71% 23.71%
4 2025-01-05 181,674 71,061 110,613 18.38% 28.62%
5 2026-03-26 168,648 74,649 93,999 15.63% 19.68%
6 2025-03-19 168,444 80,680 87,764 19.70% 21.43%
7 2024-10-29 163,092 50,839 112,254 12.13% 26.78%
8 2025-10-29 162,505 81,724 80,782 20.83% 20.59%
9 2026-03-29 160,159 93,048 67,111 21.19% 15.29%
10 2026-03-22 158,410 73,873 84,537 15.66% 17.92%
11 2024-03-24 157,573 44,422 113,152 11.20% 28.52%
12 2025-04-12 154,573 87,326 67,247 19.56% 15.06%
13 2026-03-15 152,727 58,854 93,873 12.97% 20.69%
14 2024-10-28 151,062 55,028 96,033 14.26% 24.89%
15 2026-04-13 145,424 39,684 105,740 9.76% 26.02%
16 2026-03-30 144,650 65,002 79,648 14.08% 17.25%
17 2025-03-06 144,420 53,421 90,999 12.34% 21.02%
18 2024-04-13 143,474 63,830 79,644 15.85% 19.78%
19 2024-04-05 143,393 60,684 82,708 14.21% 19.36%
20 2024-03-29 141,873 44,237 97,636 10.56% 23.30%
==============================================================================================================
Hour-of-Day Curtailment Profile (CT = UTC-5/6) | All Available Data
==============================================================================================================
Average MWh curtailed per hour-of-day, all years combined
Hr UTC CT approx Solar Curt Solar Rate Wind Curt Wind Rate
---------------------------------------------------------------------------
0:00 19:00 CT 110 4.05% 512 3.77% S: W:|
1:00 20:00 CT 9 4.17% 479 3.27% S: W:|
2:00 21:00 CT 4 42.56% 578 3.61% S: W:|
3:00 22:00 CT 4 53.99% 665 3.92% S: W:|
4:00 23:00 CT 3 58.30% 713 4.10% S: W:|
5:00 00:00 CT 3 56.71% 743 4.26% S: W:|
6:00 01:00 CT 2 52.39% 740 4.31% S: W:|
7:00 02:00 CT 2 53.03% 737 4.39% S: W:|
8:00 03:00 CT 2 45.45% 727 4.47% S: W:|
9:00 04:00 CT 2 44.60% 676 4.30% S: W:|
10:00 05:00 CT 2 50.40% 583 3.86% S: W:|
11:00 06:00 CT 2 12.66% 484 3.32% S: W:|
12:00 07:00 CT 26 2.95% 443 3.17% S: W:|
13:00 08:00 CT 184 3.31% 468 3.57% S: W:|
14:00 09:00 CT 677 5.37% 636 5.16% S:| W:|
15:00 10:00 CT 1,141 6.67% 801 6.80% S:|| W:||
16:00 11:00 CT 1,326 7.08% 863 7.53% S:||| W:||
17:00 12:00 CT 1,351 6.96% 878 7.81% S:||| W:||
18:00 13:00 CT 1,326 6.76% 878 7.85% S:||| W:||
19:00 14:00 CT 1,355 6.92% 909 7.98% S:||| W:||
20:00 15:00 CT 1,415 7.36% 969 8.24% S:||| W:||
21:00 16:00 CT 1,418 7.76% 1,017 8.33% S:||| W:||
22:00 17:00 CT 1,098 7.14% 956 7.54% S:|| W:||
23:00 18:00 CT 472 5.28% 721 5.54% S:| W:|
==============================================================================================================
Year-over-Year Trend | All Available Data
==============================================================================================================
PRIMARY metric: curtailment RATE (%) -- sampling-invariant, valid for cross-year comparison.
SECONDARY: estimated MWh (normalized) -- see Data Quality caveat; use for context only.
Curtailment Rates (solar_rate = curtailed/available; valid regardless of interval change):
Year Solar Rate Wind Rate Solar Curt Days Wind Curt Days Rate YoY notes
----------------------------------------------------------------------------------
2024 5.90% 4.59% 334 334
2025 5.87% 4.76% 363 363 Solar -0.02pp Wind +0.17pp
2026 10.31% 7.00% 127 128 Solar +4.44pp Wind +2.24pp
Estimated MWh (CAUTION: cross-year comparison is a sampling estimate, not measured):
Year Solar est MWh Wind est MWh Combined est [Raw uncorr]
--------------------------------------------------------------------
2024 2,851,863 4,954,021 7,805,884 [2,601,626]
2025 4,206,333 5,743,242 9,949,575 [3,845,361]
2026 2,763,183 3,416,081 6,179,264 [6,252,420]
[Raw] = uncorrected sum before ×3 normalization -- shows the artifact directly.
==============================================================================================================
EIA-Corrected Curtailment Rates | All Available Data
==============================================================================================================
Context: SCED 60-Day Disclosure went from ~30% solar coverage (pre-Dec 2025) to ~100%
(Dec 2025+). HSL-based rates in the Trend section are NOT comparable across this boundary.
These metrics use raw SCED + real EIA measurements -- consistent across all years.
% of Potential = raw SCED curtailed / (EIA generated + raw SCED curtailed)
'Of all solar/wind that COULD have generated, what fraction was prevented?'
% of Peak = raw SCED curtailed / (EIA seasonal peak MWh × season hours)
'If every hour was the best-ever hour, what fraction of capacity was wasted?'
Annual summary:
Year Sol % Pot Wnd % Pot Sol % Peak Wnd % Peak Notes
-------------------------------------------------------------------
2024 2.05% 1.57% 0.55% 0.74%
2025 2.22% 1.98% 0.59% 0.94% Sol +0.17pp Wnd +0.40pp
2026 7.41% 5.47% 2.00% 2.96% Sol +5.19pp Wnd +3.49pp
Monthly % of Potential -- Solar (curtailed / (EIA solar gen + curtailed)):
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
------------------------------------------------------------------------------------------------------------------------------------------------------
2024 — 4.00% 3.08% 5.77% 1.92% 1.61% 0.94% 0.32% 0.83% 2.28% 2.02% 2.29%
2025 3.41% 2.27% 5.34% 3.49% 1.72% 1.80% 0.94% 0.38% 1.03% 2.22% 1.98% 4.71%
2026 8.61% 11.95% 13.12% 7.89% 1.68% 0.00% — — — — — —
Monthly % of Potential -- Wind (curtailed / (EIA wind gen + curtailed)):
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
------------------------------------------------------------------------------------------------------------------------------------------------------
2024 — 2.03% 2.44% 2.89% 1.27% 1.08% 0.29% 0.14% 0.43% 1.89% 2.23% 1.23%
2025 1.67% 1.38% 2.95% 2.86% 1.66% 1.18% 0.53% 0.31% 0.24% 1.32% 1.81% 5.83%
2026 6.61% 6.58% 8.33% 6.16% 1.46% 0.00% — — — — — —
Takeaways:
% of Potential rose ~3-5x from 2024 to 2026 -- real growth, not a SCED artifact.
Monthly detail shows which months drive the annual change.
HSL-based rates (Trend section) remain valid within 2026 (full SCED coverage).
==============================================================================================================
HB_SOUTH vs HB_WEST Basis | All Available Data | 'Location premium vs the Permian bottleneck'
==============================================================================================================
Spread = HB_SOUTH DAM minus HB_WEST DAM ($/MWh).
Positive = South earns more than West Texas.
Belly = 09:00-16:00 CT: peak solar hours when West Texas congestion is sharpest.
A widening belly spread = West Texas curtailment intensifying at midday.
South projects earn this premium in exactly the hours when West Texas suffers.
Year All-Hrs S-W $/MWh Belly (9-4 CT) S-W $/MWh
-------------------------------------------------------
2024 -0.22 +3.85
2025 -0.90 +3.66
2026 +2.54 +7.87
A positive and growing belly spread is a lease-table advantage:
South projects earn this $/MWh more than an equivalent West Texas project
in the exact midday hours that determine solar project economics.
==============================================================================================================
Hub-Basis Stress | All Available Data | HB_SOUTH minus HB_WEST | 'South premium during generation and curtailment hours'
==============================================================================================================
Basis = HB_SOUTH − HB_WEST ($/MWh). Same sign convention as the section above.
Positive = South earns MORE than West Texas. Negative = South discount vs West.
Three weights show where the South premium (or discount) concentrates:
Solar-weighted = basis during solar generation hours
Wind-weighted = basis during wind generation hours
Curtail-weighted = basis during curtailment events (worst locational exposure for West)
'S>0/W<0 %' = hours where HB_SOUTH was positive while HB_WEST was negative:
West Texas projects PAY to generate; South projects earn. Starkest divergence.
Year Solar-wtd Wind-wtd Curt-wtd S>0/W<0 % Note
---------------------------------------------------------------------------
2024 +2.54 +1.83 +7.33 4.9% Material South premium during curtailment
2025 +2.85 +1.00 +8.03 3.8% Material South premium during curtailment
2026 +8.91 +6.20 +13.84 11.6% Large South premium during curtailment
Curtailment-weighted basis is the key metric for West Texas projects:
it shows the South premium specifically during curtailment events.
A large positive curtailment-weighted basis = South projects earn more
in exactly the hours when West Texas projects are being curtailed.
Transmission investment (Permian 765kV) compresses this spread.
==============================================================================================================
PART 6: GREGORY_RN BASIS vs HB_SOUTH | All Available Data
==============================================================================================================
Basis = GREGORY_RN DAM minus HB_SOUTH DAM ($/MWh), matched hour-by-hour.
Solar-hours basis = same, restricted to 10:00-17:00 CENTRAL -- the hours a solar
project actually generates, which is the number that matters for the lease/build call.
GREGORY_RN pricing only starts 2026-06-02 -- too short a window yet for a trend fit
(see Part 7, POV note [5]); this is a snapshot, not yet a trend.
Metric Avg $/MWh Days
----------------------------------------------------
All-hours basis -0.91 42
Solar-hours (10-17 CT) basis -1.12 42
Coverage: 2026-06-02 through 2026-07-24 (42 days).
Solar-hours basis was NEGATIVE (node cheaper than HB_SOUTH) on 29/42 days.
==============================================================================================================
PART 7: POINT OF VIEW & DATA NOTES | Read Before Trusting a Number
==============================================================================================================
Some questions here are impossible to answer without taking a POV on the data.
The fix is not to quietly pick one -- it's to say so. Every number in Parts 1-6
that depends on one of these choices is built on a bullet below.
[1] CURTAILMENT DEFINITION -- PHYSICAL, not economic.
curtailment = max(0, HSL - Base Point), UNCONDITIONAL (no price filter).
curtailment_config.py's separate price<=0 'flagged' concept (RESIDUAL_MIN_MW /
PRICE_MAX_MWH) is a DIFFERENT dashboard metric, not what this report sums.
[Step 0 finding, 2026-07: an earlier plan draft called this 'economic curtailment' --
the code never had a price filter. Corrected here; a genuine price-filtered
curtailment view would be a new variant to build, not a bug fix.]
[2] INTERVAL NORMALIZATION -- all SCED-derived MWh are scaled by 12/avg_ipr.
ERCOT's SCED disclosure moved from 15-min to 5-min intervals (~Dec 2025); a naive
SUM(curtail_mwh) on the raw table WILL differ from this report's numbers BY DESIGN.
TRUST RATES (%), not absolute MWh levels, across years (see Data Quality section
above). This is very likely the #1 source of 'report vs. raw SQL inconsistency'
that Opus-class reviews keep flagging.
[3] DAM vs RTM -- both shown where data allows; DAM is the default trend basis.
DAM = what a hedged/contracted project earns; RTM = what a pure merchant earns.
2026 RTM has real gaps at HB_SOUTH (Jan + Jun 2026, see 'HB_SOUTH RTM Data Gap'
above) and a known HB_HOUSTON hole Feb-May 2026. Parts 1-2's trend/extrapolation
use DAM for exactly this reason; RTM is shown alongside per month wherever coverage
is >=50% of that month's DAM hours (below that, RTM is left NULL, not faked).
[4] EIA vs ERCOT/SCED generation -- two independent sources; checked, they agree.
Parts 1, 2 and 4's economics use EIA hourly generation (ERCOT-system, not
hub-restricted); Part 5's curtailment uses ERCOT's own SCED disclosure. Step 0
(2026-07) independently recomputed both with matching coverage windows and found
them within 0.3% for 2024-2025, ~3-4% for partial 2026 -- cleared, not a bug.
[5] HUB PRICING IS A LOCATIONAL PROXY, not nodal settlement.
Every $/MWh figure in Parts 1-4 prices ERCOT-system-wide generation at a single
hub (HB_SOUTH primary; HB_WEST/NORTH/HOUSTON where shown). A real project settles
at its own resource node, which can differ from the hub by tens of $/MWh (Part 6).
Gregory's own node prices only start 2026-06-02 -- too short a window yet for a
trend fit.
[6] TOTALGRID FORMULA CHANGE, 2026-06-01.
GridData's TotalGrid formula changed on this date (fix_totalgrid_post_june.py);
GridData itself only starts 2025-06-28, node prices only start 2026-06. Any series
crossing 2026-06-01 that touches TotalGrid reads corrected post-fix values
throughout -- but the PRE-2026-06-01 period used a different formula, so don't
naively extrapolate TotalGrid trends across that boundary.
[7] ALL TIMESTAMPS IN THIS REPORT ARE CENTRAL TIME; the raw DBs mix UTC and local.
sced_curtailment/sced_battery/prices_hourly are stored UTC and converted here via
ct_date/ct_year/ct_month/ct_hour (Step 0 + Deliverable B, 2026-07). eia_generation is
deliberately LEFT in UTC (labeled 'Hr UTC' wherever printed) -- converting it would
ripple into every EIA-joined economics function; a stated POV, not a bug. GridData
columns in ErcotGridData.db are already local. Mixing UTC and Central day/month keys
when joining across these is the most common source of subtle errors in this project --
grep for 'eia_by_day|eia_day_grid|by_ym_eia' before adding a new cross-reference.
[8] BATTERY 4h / 25%-of-PV SIZING (Part 4) -- a market-typical default, not a site plan.
No developer-quoted battery ratio exists for Jeff's own site. See the REAL-WORLD
CAVEAT printed in Part 4: his developer is currently blocked on ERCOT battery
interconnection approval (charging = load, triggers a load-interconnection study).
Part 4's numbers are market context, not a commitment his site can realize them.
[9] CAPTURE 'RATE' COLUMNS ARE $/MWh CAPTURE PRICES, not percentages.
Matches every other capture-price usage in this report and in build_ai_export.py's
AI export (a deliberate naming continuity, documented deviation from the original
Deliverable A spec wording).
This appendix intentionally repeats caveats already printed inline above (Data
Quality, the DEC 2025 three-confound warning, HB_SOUTH RTM Data Gap) -- collected here
as ONE place an AI or a human can read cold and get the full POV picture without hunting.
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Data coverage: 2024-02-01 to 2026-05-25
Run with --all-months for a full-year view.
Raw daily data (with both raw+norm cols): C:\Ginners\Programs\ErcotGrid\ErcotFolders\ErcotGridCurtailment\curtailment_daily.csv
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