Analysis of Load Reductions in ERCOT Transmission Charges

Analysis of Load Reductions Associated with 4-CP Transmission Charges in ERCOT Carl L Raish Principal Load Profiling and Modeling Demand Side Working Group April 22, 2016

Counts of ESIIDs on REP Sponsored Price/Demand Response Programs Product Type Description/Example 2013 2014 2015 Time of Use Free Nights , FreeWeekends 135,320 290,328 328,642 Rebates for DR during high price intervals Price indexed to 15-minute LMPs Fixed price block with indexed price for use in excess of the block Direct control of end-uses not necessarily tied to high price events Peak Rebate 2,468 413,772 499,085 Real Time Pricing 4,358 9,700 5,621 Block & Index Pricing 23,928 6,976 9,574 Other Load Control 3,488 19,304 14,927 2 PUBLIC

How 4CP Works BUSIDRRQ customers 700 kW or served at transmission (69 kV) voltage are subject to 4CP charges. Simple average of the metered load during ERCOT system monthly peak 15- minute intervals in four summer months -- June, July, August & September. Multiplied by the applicable prevailing TDSP Tariff, as approved by PUC. Is the basis for the monthly 4CP-based rates for the following calendar year. Analysis for this report was limited to ESIIDs in competitive ERCOT areas with BUSIDRRQ profile types (ERCOT already has the data for retail settlement purposes). Municipals and COOPs can benefit by reducing 4CP loads, a few indicated they do actively reduce their load. Only aggregate data available for them, and, to date, load reductions for most NOIEs cannot be detected at that level An initial look at the limited number of NOIEs with significant reductions using the methodology presented indicates about 300 MW of 4CP related load reduction. 3 PUBLIC

Analysis Methodology 1. Identify 4CP and Near-CP days. 2. Identify High-Price days. 3. Classify customers by voltage level (Transmission/Distribution) and weather sensitivity. 4. Classify customers subject to 4CP charges: a. Develop baselines (WS and NWS) for each customer. b. Classify customers as those who reduce load at significant levels/frequencies and those who do not. c. Classify customers by type of reduction: 1) Load reduction that targets the afternoon hours of 4CP/Near-CP days. 2) Load reduction that starts early in the day and continues through the 4CP time period. 5. Calculate load reductions for specific 4CP/Near-CP days. a. Limited to customers identified in step 3 those who reduce load. b. Include customer s load in over-all reduction calculation if they have a significant reduction on the specific day. c. Classify customer by load-factor category and calculate sub-totals. 6. Evaluate the interaction of high price events and 4CP response: a. Identify customers reported by their retailer as being on time-sensitive rates (real-time /block and index pricing). b. Quantify and compare their load reductions on 4CP and High-Price days. 4 PUBLIC

Identify 4CP and Near-CP Days ERCOT Load on CP Day 9/8/2015 70,000.0 Response not apparent by examining ERCOT system Load 649 MW of 4 CP Response was ultimately found on 9/08/2015 About 1% of the ERCOT load 60,000.0 50,000.0 40,000.0 MW 30,000.0 20,000.0 10,000.0 - 0 10 20 30 40 50 60 70 80 90 Interval BUSIDRRQ Load on CP Day 9/8/2015 20,000.0 18,000.0 Drilling down to BUSIDRRQ load on that day doesn t provide much help 649 MW is about 4% of the total BUSIDRRQ load 16,000.0 14,000.0 12,000.0 MW 10,000.0 8,000.0 6,000.0 4,000.0 2,000.0 - 0 20 40 60 80 Interval 5 PUBLIC

Identify 4CP and Near-CP Days Transmission Customer Class Load 9/8/2015 5,000 1200 4,500 1000 4,000 3,500 800 3,000 2,500 600 2,000 400 1,500 1,000 200 500 0 0 0 10 20 30 40 50 60 70 80 90 Base Actual HR 16:00 - 17:00 Prices About 300 transmission ESIIDs initially found to be reducing by 270 MW. Reduction is about 7% of the class load. The very high group daily load factor, results in a clear indicator of when a significant load reduction is occurring. 6 PUBLIC

Identify 4CP and Near-CP Days Analyzed Transmission Class total load for all summer weekdays. Used the Non-weather sensitive baseline excluding CP and high-price days Calculated and applied the Day-of-adjustment. Days with more than 100 MW of response for hour-ending 17:00 were classified as Near-CP days. Found 80 Near-CP days from 2008 2015. CP and Near-CP days were analyzed for this report 7 PUBLIC

Transmission Load on Near CP Response Days 6/25/2015 6/9/2015 6/24/2015 5,000 1200 5,000 1200 5,000 1200 4,800 4,800 4,800 1000 1000 1000 4,600 4,600 4,600 4,400 4,400 4,400 800 800 800 4,200 4,200 4,200 4,000 600 4,000 600 4,000 600 3,800 3,800 3,800 400 400 400 MW17 Reduce = 170 MW17 Reduce = 154 MW17 Reduce = 150 3,600 3,600 3,600 3,400 3,400 3,400 200 200 200 3,200 3,200 3,200 3,000 0 3,000 0 3,000 0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Base Actual HR 16:00 - 17:00 Prices Base Actual HR 16:00 - 17:00 Prices Base Actual HR 16:00 - 17:00 Prices 7/29/2015 7/14/2015 7/27/2015 5,000 1200 5,000 1200 5,000 1200 4,800 4,800 4,800 1000 1000 1000 4,600 4,600 4,600 4,400 4,400 4,400 800 800 800 4,200 4,200 4,200 4,000 600 4,000 600 4,000 600 3,800 3,800 3,800 400 400 400 MW17 Reduce = 218 MW17 Reduce = 165 MW17 Reduce = 275 3,600 3,600 3,600 3,400 3,400 3,400 200 200 200 3,200 3,200 3,200 3,000 0 3,000 0 3,000 0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Base Actual HR 16:00 - 17:00 Prices Base Actual HR 16:00 - 17:00 Prices Base Actual HR 16:00 - 17:00 Prices 8 PUBLIC

Transmission Load on Near CP Response Days 8/11/2015 9/2/2015 8/6/2015 5,000 1200 5,000 1200 5,000 1200 4,800 4,800 4,800 1000 1000 1000 4,600 4,600 4,600 4,400 4,400 4,400 800 800 800 4,200 4,200 4,200 4,000 600 4,000 600 4,000 600 3,800 3,800 3,800 400 400 400 3,600 3,600 MW17 Reduce = 137 MW17 Reduce = 102 MW17 Reduce = 102 3,600 3,400 3,400 3,400 200 200 200 3,200 3,200 3,200 3,000 0 3,000 0 3,000 0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Base Actual HR 16:00 - 17:00 Prices Base Actual HR 16:00 - 17:00 Prices Base Actual HR 16:00 - 17:00 Prices 9/3/2015 9/4/2015 5,000 1200 5,000 1200 4,800 4,800 1000 1000 4,600 4,600 4,400 4,400 800 800 4,200 4,200 4,000 600 4,000 600 3,800 3,800 400 400 MW17 Reduce = 183 MW17 Reduce = 131 3,600 3,600 3,400 3,400 200 200 3,200 3,200 3,000 0 3,000 0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Base Actual HR 16:00 - 17:00 Prices Base Actual HR 16:00 - 17:00 Prices 9 PUBLIC

Historic 4CP/Near CP Intervals (2009-2015) CP Near-CP Total Most common 4CP / Near CP intervals are 4:45 and 5:00 PM 14:30 14:45 15:00 15:15 15:30 15:45 16:00 16:15 16:30 16:45 17:00 0 0 0 0 0 0 3 1 6 7 11 1 0 1 1 3 1 6 0 1 0 1 1 3 1 9 1 24 33 29 18 26 18 CP Near-CP Total Monday Tuesday Wednesday Thursday Friday 7 5 10 4 2 7 14 26 28 19 16 Tuesday and Wednesday are most likely to be 4CP days 21 18 15 14 10 PUBLIC

Identify High-Price Days Pulled load zone prices for 2011 2015 (ERCOT was operating under Nodal Market Rules). Took simple average of interval-by-interval prices across load zones. Identified days with 4 or more consecutive intervals with prices greater than $200 / MWh. Number of Days with Consecutive Prices Over $200/MWh Consecutive Intervals Year Total 4 6 3 3 3 0 5-8 12 5 6 6 3 9-12 3 2 1 3 5 13-16 6 1 0 1 0 >17 3 1 0 1 1 75 High-Price days identified 2011 2012 2013 2014 2015 30 12 10 14 9 Average Price Distribution for Consecutive Prices Over $200/MWh Year $200_to_250 $251_to_300 $301_to_400 $401_to_500 $501_to_600 $601_to_700 $701_to_800 $801_to_900 $901_to_1000 $1001_to_2000 $2001_to_3000 2011 1 1 7 2 7 2012 1 2 4 2 1 2013 1 2 1 1 1 2014 1 2 7 2 1 3 2015 2 3 1 3 1 3 1 5 3 2 1 5 1 1 1 1 1 11 PUBLIC

Classify customers subject to 4CP charges All ESIIDs subject to 4-CP charges were base-lined. Classify customers by weather sensitivity. Calculate R2 for distribution ESIIDs on daily-use for summer non-holiday weekdays versus average daily dry bulb temperature for the analysis year. If R2 0.6 treat ESIID as weather sensitive. Non-weather sensitive baseline: 20 Non-CP days (before and after) occurring closest to the day being analyzed. Weather sensitive: using regression baseline (ERCOT load profile models) using 3 years of historical interval data. Scalar Day-of-adjustment factor from midnight to 3:00 PM was applied to baseline. Non-CP days defined as weekday, non-holiday days. Excluded CP days and high-price days. Also excluded Near-CP days. 12 PUBLIC

Classify customers subject to 4CP charges Classify customers that respond on 4CP/Near-CP days Used baselines to calculate hour-ending 5:00 pm 4CP and Near-CP reductions Calculate reduction percent and frequency for three years closest to the analysis year (42 days of possible reductions for 2015) Otherwise, looked at reductions for the analysis year plus year-after (except 2015) To improve the classification of ESIIDs that started responding to 4-CP starting with the analysis year 2015 Responder Classification Reduce Freq Pct Reduce MW Pct Transmission Distribution NWS Distribution WS Group Total 3-yr 1-yr 3-yr 1-yr 3,996 3-yr 1-yr 0 1 2 3 4 175 11 743 204 49 4,914 50-100% 40-50% 30-40% 25-30% >2% >5% >10% >20% 70 34 16 2 2,223 1,332 673 234 285 97 20 698 268 35 8 1 3 - 84 2 - Total responders 122 20 4,312 636 1,003 256 6,349 6,349 (56%) of 11,338 customers classified as responders for 2015 13 PUBLIC

Classify customers subject to 4CP charges Responder ESIIDs from previous step were then classified into two response categories based on how they modified usage on CP and Near-CP days Reduced CP Hour Use -- ESIID that reduced usage during 4:00 PM 5:00 PM on CP/Near-CP days but did not reduce significantly ahead of those times. Reduced Day Use -- ESIIDs that reduced CP Hour Use and also usually lowered usage from 9:00 AM 4:00 PM) on those days. Day use reduction: The average day use reduction was > 10%, and The average number of intervals below the baseline was >= 20 If 50%, or more, of days with CP Hour reduction also had day use reduction, customer was classified as reducing day use 2015 Responder Classification Transmission Distribution NWS Distribution WS cp-hour 98 day-use 46 cp-hour 4,349 day-use cp-hour 1,142 day-use 616 113 14 PUBLIC

Calculate load reductions for specific 4CP/Near-CP days Calculations limited to customers that met all of the following: Customers classified as responders by the previous step. Baseline indicated the customer did reduce load for the hour ending 5:00 pm for that day. Customer reduced load by at least 10%, or, if less than 10%, by more than its average 5:00 pm reduction determined by the previous classification step. If the customerwas classified as targeting its reduction for the afternoon hours, a scalar day-of-adjustment was applied to the baseline. Adjustment factor was calculated as the ratio of actual- to baseline-use from midnight to 3:00 pm on the CP/Near-CP day. Baseline intervals for the entire day were then multiplied by the adjustment factor. If the customer was classified as starting to reduce earlier in the day, no scalar day-of-adjustment adjustment was applied to its baseline. 15 PUBLIC

Reductions by Response Type on 4 CP Days - 2015 Day-use Response Peak Response June 10, 2015 June 10, 2015 500.0 2500.0 450.0 400.0 2000.0 350.0 300.0 1500.0 MW MW 250.0 200.0 1000.0 CP Reduce = 354 CP Reduce = 163 150.0 100.0 500.0 50.0 0.0 0.0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Interval Interval Actual Baseline Reduce HR 17:00 Actual Baseline Reduce HR 17:00 July 30, 2015 July 30, 2015 2500.0 500.0 450.0 2000.0 400.0 350.0 1500.0 300.0 MW MW 250.0 1000.0 CP Reduce = 412 CP Reduce = 195 200.0 150.0 500.0 100.0 50.0 0.0 0.0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Interval Interval Actual Baseline Reduce HR 17:00 Actual Baseline Reduce HR 17:00 16 PUBLIC

Reductions by Response Type on 4 CP Days - 2015 Day-use Response Peak Response August 10, 2015 August 10, 2015 2500.0 500.0 450.0 2000.0 400.0 350.0 1500.0 300.0 MW MW 250.0 1000.0 200.0 150.0 CP Reduce = 185 CP Reduce = 420 500.0 100.0 50.0 0.0 0.0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Interval Interval Actual Baseline Reduce HR 17:00 Actual Baseline Reduce HR 17:00 September 8, 2015 September 8, 2015 2500.0 500.0 450.0 2000.0 400.0 350.0 1500.0 300.0 MW MW 250.0 1000.0 200.0 CP Reduce = 424 CP Reduce = 221 150.0 500.0 100.0 50.0 0.0 0.0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Interval Interval Actual Baseline Reduce HR 17:00 Actual Baseline Reduce HR 17:00 17 PUBLIC

Total Reductions on 4 CP Days - 2015 July 30, 2015 June 10, 2015 2500.0 2500.0 2000.0 2000.0 1500.0 1500.0 MW MW 1000.0 1000.0 CP Reduce = 517 CP Reduce = 606 500.0 500.0 0.0 0.0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Interval Interval Actual Baseline Reduce HR 17:00 Actual Baseline Reduce HR 17:00 September 18, 2015 August 10, 2015 2500.0 2500.0 2000.0 2000.0 1500.0 1500.0 MW MW CP Reduce = 604 CP Reduce = 645 1000.0 1000.0 500.0 500.0 0.0 0.0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Interval Interval Actual Baseline Reduce HR 17:00 Actual Baseline Reduce HR 17:00 18 PUBLIC

Non-Responders on July 30, 2015 Total Load for customers initially classified as responders who did not appear to respond on July 30, 2015. July 30, 2015 4000 3500 3000 2500 MW 2000 The method seems to work no significant response that s unaccounted for. 1500 1000 500 0 0 10 20 30 40 50 60 70 80 90 Interval Actual Baseline HR 17:00 Distribution NWS Distribution WS July 30, 2015 July 30, 2015 7000 2500 6000 2000 5000 1500 4000 MW MW 3000 1000 2000 500 1000 0 0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Interval Interval Actual Baseline HR 17:00 Actual Baseline HR 17:00 19 PUBLIC

4 CP / Near CP 15-Minute Response 2009 - 2015 Near- CP Time Near- CP Time Near- CP Time CP Time Reduce MW Near-CP Date Reduce MW CP Time Reduce MW Near-CP Date Reduce MW CP Time Reduce MW Near-CP Date Reduce MW CP Date CP Date CP Date 6/25/2009 7/13/2009 8/5/2009 9/3/2009 16:15 17:00 16:00 16:00 445.1 354.5 408.0 413.4 6/16/2009 6/23/2009 6/24/2009 7/8/2009 7/17/2009 7/31/2009 8/4/2009 8/6/2009 9/2/2009 17:00 16:45 16:30 16:45 16:45 16:00 17:00 17:00 17:00 292.3 294.5 421.1 289.5 322.7 364.3 322.8 291.6 351.8 6/21/2010 7/16/2010 8/23/2010 9/14/2010 16:45 16:30 16:00 16:45 331.6 421.9 415.0 510.8 6/16/2010 6/18/2010 6/22/2010 7/14/2010 7/15/2010 8/3/2010 8/4/2010 8/5/2010 8/11/2010 8/20/2010 9/1/2010 9/13/2010 16:30 16:00 16:30 17:00 16:45 16:30 16:45 16:30 15:15 15:30 15:30 16:30 406.2 414.0 430.5 482.1 551.4 468.4 488.3 427.0 484.0 460.8 464.9 350.8 6/15/2011 7/27/2011 8/3/2011 9/2/2011 17:00 16:30 17:00 16:30 579.5 544.2 697.9 597.5 6/14/2011 6/16/2011 6/17/2011 6/28/2011 7/7/2011 7/13/2011 7/14/2011 8/1/2011 8/2/2011 8/5/2011 8/9/2011 8/10/2011 8/23/2011 9/1/2011 9/13/2011 17:00 17:00 16:45 17:00 16:45 17:00 16:45 16:45 16:45 16:45 16:30 17:00 16:45 16:45 16:30 454.6 388.1 514.0 412.6 436.6 546.8 580.2 448.7 627.5 474.3 376.3 332.5 380.2 529.8 502.0 average 405.3 n=9 average 327.8 average 419.8 n=12 average 452.4 average 604.8 n=15 average 466.9 6/26/2012 7/31/2012 8/1/2012 9/5/2012 16:30 17:00 17:00 17:00 615.2 547.9 481.4 603.1 6/11/2012 6/25/2012 7/20/2012 7/30/2012 8/2/2012 9/4/2012 9/6/2012 9/7/2012 9/28/2012 16:30 17:00 16:00 16:45 16:45 16:45 17:00 16:30 14:30 478.9 574.9 484.0 596.6 465.6 472.5 590.3 623.9 277.8 6/27/2013 7/31/2013 8/7/2013 9/3/2013 17:00 17:00 16:45 16:45 562.7 574.9 567.7 447.2 6/19/2013 6/26/2013 6/28/2013 7/9/2013 7/10/2013 8/1/2013 8/6/2013 9/4/2013 9/19/2013 16:30 17:00 17:00 16:45 17:00 16:45 16:45 17:00 16:30 319.5 364.2 511.6 325.1 383.3 550.7 448.8 444.2 318.2 6/30/2014 7/21/2014 8/25/2014 9/10/2014 16:30 16:45 17:00 17:00 578.5 257.9 700.5 712.1 7/8/2014 7/14/2014 7/22/2014 7/25/2014 8/6/2014 8/8/2014 8/21/2014 8/22/2014 9/2/2014 9/9/2014 16:30 15:00 16:45 17:00 17:00 15:45 16:00 16:30 16:30 16:45 366.9 132.2 420.1 442.7 384.2 414.2 300.2 510.0 654.3 530.9 average 561.9 n=9 average 507.2 average 538.1 n=9 average 407.3 average 562.3 n=10 average 415.6 6/10/2015 7/30/2015 8/10/2015 9/8/2015 16:45 16:45 17:00 16:30 516.5 606.4 604.3 645.1 6/9/2015 6/24/2015 6/25/2015 7/14/2015 7/27/2015 7/29/2015 8/6/2015 8/11/2015 9/2/2015 9/3/2015 9/4/2015 15:30 16:30 16:45 16:45 16:30 16:45 16:45 16:00 17:00 16:45 16:00 285.8 381.5 502.6 489.6 585.0 616.0 527.1 565.7 373.3 424.7 422.7 average 593.1 n=11 average 470.4 20 PUBLIC

Hour Ending 17:00 Response on 4 CP Days 2009 - 2015 Largest Near CP17MW-CP-Int 421.1 364.3 322.8 351.8 430.5 551.4 488.3 465.0 514.0 580.2 627.5 529.8 574.9 596.6 465.6 623.9 511.7 383.3 550.7 444.2 - 622.7 575.9 504.8 351.9 475.6 444.7 327.9 4-CP Day MW17 Reductions 2009 - 2015 Year Month CP MW-17 ESIIDs 800.0 2009 June July August September June July August September June July August September June July August September June July August September June July August September June July August September 434.1 355.1 463.1 423.6 327.0 442.8 447.7 521.5 574.2 543.7 693.0 595.7 616.6 541.1 460.6 593.9 556.1 568.5 551.7 443.7 565.5 253.8 701.0 705.8 501.3 602.8 623.9 649.5 431.4 328.2 311.4 332.2 453.2 572.9 507.5 356.3 525.9 600.0 632.1 528.5 568.8 596.4 464.6 622.8 575.8 397.8 574.5 440.1 - 442.7 510.0 654.3 516.5 606.4 604.3 645.1 1,533 1,198 1,238 1,122 1,246 1,503 1,425 1,168 1,475 1,357 1,605 1,441 1,413 1,443 1,390 1,291 1,690 1,402 1,566 1,401 1,530 1,309 1,552 1,379 1,652 1,954 2,159 1,822 700.0 600.0 MW 500.0 2010 400.0 300.0 200.0 2009-Jul 2010-Jul 2011-Jul 2012-Jul 2013-Jul 2014-Jul 2015-Jul 2014-Aug 2009-Aug 2010-Aug 2011-Aug 2012-Aug 2013-Aug 2015-Aug 2009-Jun 2010-Jun 2011-Jun 2012-Jun 2012-Sep 2013-Jun 2014-Jun 2015-Jun 2009-Sep 2010-Sep 2011-Sep 2013-Sep 2014-Sep 2015-Sep 2011 Year-Mon MW17 Reduce MW17Largest Near-CP 2012 ESIIDs with 4-CP Reductions 2009 - 2015 2,500 2,300 2,100 2013 1,900 1,700 ESIIDs 1,500 2014 1,300 1,100 900 700 2015 2009-Aug 2010-Aug 2011-Aug 2012-Aug 2013-Aug 2014-Aug 2015-Aug 2009-Jul 2010-Jul 2011-Jul 2012-Jul 2013-Jul 2014-Jul 2015-Jul 2009-Jun 2009-Sep 2010-Jun 2010-Sep 2011-Jun 2011-Sep 2012-Jun 2012-Sep 2013-Jun 2013-Sep 2014-Jun 2014-Sep 2015-Jun 2015-Sep Year-Mon ESIIDs Respond 21 PUBLIC

4 CP 15-Minute Response 2009 - 2015 4-CP Peak Shifting Peak with no 4-CP Reduction Actual Peak Date Time 16:30 17:00 16:30 17:00 16:30 17:00 Date Time 16:45 16:45 16:45 16:45 16:45 16:45 7/16/2010 6/15/2011 7/27/2011 8/3/2011 6/26/2012 8/10/2015 7/15/2010 6/15/2011 7/27/2011 8/3/2011 6/26/2012 8/10/2015 Of the 28 4CP intervals since 2009, only 6 appear to have been shifted by 4CP response 3 shifted peak one interval later (all from 16:45 to 17:00) 2 shifted one interval earlier (both from 16:45 to 16:30) 1 (7/16/2010) shifted one day later and one interval earlier 22 PUBLIC

Number of ESIIDs with 4 CP Responses 2015 Load Factor High Reduce Hour Medium Reduce Hour Low Reduce Hour Total Reduce Hour Reduce Day Non Respond Reduce Day Non Respond Reduce Day Non Respond Reduce Day Non Respond Response Type June Transmission Distribution NWS Distribution WS 11 56 37 104 1 1 2 4 135 13 322 144 479 6 3,917 1,029 5,043 97 9 14 237 12 263 2,366 2,438 31 1,080 1,300 33 21 287 44 352 263 1,279 697 2,111 49 30 85 702 7,562 1,767 9,592 6 41 187 Total 717 July Transmission Distribution NWS Distribution WS 10 100 60 170 1 2 3 6 136 18 375 149 542 10 47 34 91 3,869 1,020 4,977 88 11 858 16 885 18 232 10 260 2,210 2,268 25 1,333 1,597 39 29 281 47 357 249 1,237 673 2,046 7,316 1,726 9,291 33 225 Total August Transmission Distribution NWS Distribution WS 12 106 96 214 1 2 2 5 134 18 393 253 664 5 3,836 4,849 93 6 19 238 11 268 2,179 2,235 29 1,388 1,794 36 25 297 43 365 256 1,231 638 2,003 57 30 92 889 21 916 7,246 1,585 9,087 920 27 370 Total September Transmission Distribution NWS Distribution WS 15 115 56 186 1 2 2 5 131 9 7 100 5 22 227 2,301 2,371 26 1,292 1,462 29 30 290 40 360 257 1,221 678 2,030 396 77 482 61 31 99 3,834 1,095 5,029 781 7,356 1,817 9,430 8 7 44 141 Total 794 256 Across the 4 months ~2,000 (17%) of the ESIIDs subject to 4CP charges responded Response rates: High LF 8%, Medium LF 11%, Low LF 32% Low LF accounts for 57% of all responders 23 PUBLIC

Hour-ending 17:00 MW Reductions on 4 CP Days - 2015 All Responding 4-CP ESIIDS Reductions for Hour Ending 17:00 High Load Factor Medium Load Factor Low Load Factor Total Total Response Peak Response Day Total Response Peak Response Day Total Response Peak Response Day Total Response Peak Response Day Response Response Response Response 4 CP Days 10-Jun-15 82.6 65.8 16.9 160.1 117.7 42.4 258.6 157.5 101.1 501.3 341.0 160.4 30-Jul-15 123.7 111.2 12.5 192.3 132.2 60.1 286.8 166.3 120.5 602.8 409.7 193.2 10-Aug-15 175.1 162.0 13.1 207.9 153.3 54.6 240.9 117.4 123.5 623.9 432.7 191.3 8-Sep-15 163.4 150.6 12.8 248.6 152.8 95.8 237.5 118.1 119.4 649.5 421.5 228.0 Near CP Day with Largest Response 11-Aug-15 74.4 72.9 1.5 167.3 127.6 39.7 155.9 112.7 43.2 397.6 313.2 84.4 Peak reduction exceeds day-use response and accounts for 67% of the total response Except for September, most of the MW response came from Low LF ESIIDs 24 PUBLIC

Hour-ending 17:00 MW Reductions on 4 CP Days - 2015 Reductions by Voltage Group Reductions for Hour Ending 17:00 Transmission Distribution Non-Weather Sensitive Distribution Weather Sensitive Total Total Response Peak Response Day Total Response Peak Response Day Total Response Peak Response Day Total Response Peak Response Day Response Response Response Response 4 CP Days 10-Jun-15 277.0 178.2 98.8 211.5 153.9 57.6 12.8 8.8 4.0 501.3 341.0 160.4 30-Jul-15 332.7 197.1 135.6 252.7 199.2 53.5 17.4 13.4 4.0 602.8 409.7 193.2 10-Aug-15 290.1 173.9 116.1 304.6 233.8 70.8 29.3 25.0 4.3 623.9 432.7 191.3 8-Sep-15 330.0 181.5 148.5 306.9 231.0 75.9 12.5 8.9 3.6 649.5 421.5 228.0 Near CP Day with Largest Response 11-Aug-15 65.3 57.8 7.5 298.2 227.2 71.0 34.1 28.2 5.9 397.6 313.2 84.4 Most of the MW response comes from Transmission and Distribution NWS ESIIDs 25 PUBLIC

Hour-ending 17:00 MW Reductions on 4 CP Days - 2015 Reductions as a Percent of Total Load Factor Group Load Response as Percent of Total Load Response as Percent of Total Load Total Reduction Responders Total Load Non-Responders Total Load Total Load Total Reduction Responders Total Load Non-Responders Total Load Total Load CP Date High Load Factor MW Medium Load Factor MW 10-Jun-15 82.6 346.6 4,959.5 5,306.1 1.6% 160.1 678.5 4,769.0 5,447.5 2.9% 30-Jul-15 123.7 371.0 4,969.2 5,340.3 2.3% 192.3 743.4 4,874.4 5,617.7 3.4% 10-Aug-15 175.1 502.0 4,855.6 5,357.6 3.3% 207.9 840.6 4,766.2 5,606.7 3.7% 8-Sep-15 163.4 476.8 4,806.6 5,283.4 3.1% 248.6 745.4 4,805.7 5,551.1 4.5% Total Low Load Factor 10-Jun-15 258.6 477.5 1,046.2 1,523.7 17.0% 501.3 1,502.6 10,774.7 12,277.3 4.1% 30-Jul-15 286.8 607.9 911.3 1,519.1 18.9% 602.8 1,722.3 10,754.9 12,477.2 4.8% 10-Aug-15 240.9 505.4 1,033.6 1,539.0 15.7% 623.9 1,847.9 10,655.4 12,503.3 5.0% 8-Sep-15 237.5 493.0 1,121.7 1,614.7 14.7% 649.5 1,715.1 10,734.0 12,449.2 5.2% Across all participants, ESIIDs reduce about 5% of their total load Low LF ESIIDs reduce the highest percent of their total load (~17%) 26 PUBLIC

Hour-ending 17:00 Reductions on 4 CP Days - 2015 Percentage of Load Reduction by Load Factor and Voltage Group High Load Factor Medium Load Factor Low Load Factor Total Reduction Percent of Total Reduction 16.5% Percent of Total Reduction 31.9% Percent of Total Reduction 51.6% Total Reduction Total Reduction Total Reduction 4 CP Days 10-Jun-15 82.6 160.1 258.6 501.3 30-Jul-15 123.7 20.5% 192.3 31.9% 286.8 47.6% 602.8 10-Aug-15 175.1 28.1% 207.9 33.3% 240.9 38.6% 623.9 8-Sep-15 163.4 25.2% 248.6 38.3% 237.5 36.6% 649.5 Transmission Distribution NWS Distribution WS Total Reduction Percent of Total Reduction 55.3% Percent of Total Reduction 42.2% Percent of Total Reduction 2.6% Total Reduction Total Reduction Total Reduction 4 CP Days 10-Jun-15 277.0 211.5 12.8 501.3 30-Jul-15 332.7 55.2% 252.7 41.9% 17.4 2.9% 602.8 10-Aug-15 290.1 46.5% 304.6 48.8% 29.3 4.7% 623.9 8-Sep-15 330.0 50.8% 306.9 47.3% 12.5 1.9% 649.5 Low LF and Transmission ESIIDs provide close to half of the total reduction 27 PUBLIC

Interaction of Price and 4-CP Response REPs provided lists of ESIIDs participating in Real Time/Block & Index Pricing annual for 2013 2015. 1,535 ESIIDs on RTP/BI pricing also are subject to 4CP charges. 828 ESIIDs were identified as 4CP responders and were analyzed to evaluate the interaction between 4CP- and Price-response. During 2013 2015, 25 days were classified as high-price days The sustained hourly prices on these high-price days ranged from $207 4,421. Two high-price days also were CP days (Sep 3, 2013 and Jul 30, 2015) and one high-price day was a Near-CP day (Aug 11, 2015). Load reductions on high-price days were quantified using the same baseline methodology as used for the 4CP/Near CP analysis Day-of-adjustment periods were varied to include intervals prior to the onset of high prices for the day. Regression was run to estimate the relationship of load reduction on high price days (excluding the 4CP and Near-CP days) to the sustained high price on those days. Independent variable was the log of price. Load reduction was set to zero if it was estimated as negative. 28 PUBLIC

Interaction of Price and 4-CP Response Estimated Load Reduction on CP Days For RTP/BI ESIIDs Estimated Price Response Esitmated Load Reduction (MW) Average Price ($/MWh) Date CP Days 6/27/2013 7/31/2013 8/7/2013 9/3/2013 6/30/2014 7/21/2014 8/25/2014 9/10/2014 6/10/2015 7/30/2015 8/10/2015 9/8/2015 267.9 253.4 255.4 166.5 183.9 11.2 281.3 183.9 213.7 291.4 244.7 228.4 98 63 92 2,333 135.3 44 146 134 44 61 337 201 38 24.9 Near-CP Day 8/11/2015 251.5 563 54.3 236.5 MW average CP/Near CP load reduction on high-price days 234.7 MW average CP load reduction on other than high-price days (excluding 7/21/2014) No significant incremental CP load reduction related to high prices RTP/BI ESIIDs do provide ~40% of the total 4CP load reduction 29 PUBLIC

Interaction of Price and 4-CP Response Estimated Load Reduction on selected CP Days For RTP/BI ESIIDs August 7, 2013 September 3, 2013 2000.0 1000.0 2000.0 1000.0 1800.0 900.0 1800.0 900.0 1600.0 800.0 1600.0 800.0 1400.0 700.0 1400.0 700.0 1200.0 600.0 1200.0 600.0 $/MWH $/MWH MW MW 1000.0 500.0 1000.0 500.0 800.0 400.0 800.0 400.0 CP Reduce = 255 CP Reduce = 167 600.0 300.0 600.0 300.0 400.0 200.0 400.0 200.0 200.0 100.0 200.0 100.0 0.0 0.0 0.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Interval Interval Actual Baseline Reduce HR 17:00 RT Prices Actual Baseline Reduce HR 17:00 RT Prices September 8, 2015 July 30, 2015 2000.0 1000.0 2000.0 1000.0 1800.0 900.0 1800.0 900.0 1600.0 800.0 1600.0 800.0 1400.0 700.0 1400.0 700.0 1200.0 600.0 1200.0 600.0 $/MWH $/MWH MW MW 1000.0 500.0 1000.0 500.0 800.0 400.0 800.0 400.0 CP Reduce = 291 CP Reduce = 228 600.0 300.0 600.0 300.0 400.0 200.0 400.0 200.0 200.0 100.0 200.0 100.0 0.0 0.0 0.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Interval Interval Actual Baseline Reduce HR 17:00 RT Prices Actual Baseline Reduce HR 17:00 RT Prices 30 PUBLIC

Interaction of Price and 4-CP Response Estimated Load Reduction on Near-CP Day For RTP/BI ESIIDs August 6, 2015 August 11, 2015 2000.0 1000.0 2000.0 1000.0 1800.0 900.0 1800.0 900.0 1600.0 800.0 1600.0 800.0 1400.0 700.0 1400.0 700.0 1200.0 600.0 1200.0 600.0 $/MWH $/MWH MW MW 1000.0 500.0 1000.0 500.0 800.0 400.0 800.0 400.0 CP Reduce = 231 CP Reduce = 252 600.0 300.0 600.0 300.0 400.0 200.0 400.0 200.0 200.0 100.0 200.0 100.0 0.0 0.0 0.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Interval Interval Actual Baseline Reduce HR 17:00 RT Prices Actual Baseline Reduce HR 17:00 RT Prices 31 PUBLIC

Interaction of Price and 4-CP Response Estimated Load Reduction on selected High-Price Non-CP Days For RTP/BI ESIIDs October 1, 2013 January 6, 2014 2000.0 1000.0 2000.0 1000.0 1800.0 900.0 1800.0 900.0 1600.0 800.0 1600.0 800.0 1400.0 700.0 1400.0 700.0 1200.0 600.0 1200.0 600.0 $/MWH $/MWH MW MW 1000.0 500.0 1000.0 500.0 800.0 400.0 800.0 400.0 MW Reduce = 72 MW Reduce = 169 600.0 300.0 600.0 300.0 400.0 200.0 400.0 200.0 200.0 100.0 200.0 100.0 0.0 0.0 0.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Interval Interval Actual Baseline Reduce HR 17:00 RT Prices Actual Baseline Reduce HR 17:00 RT Prices May 18, 2015 August 12, 2015 2000.0 1000.0 2000.0 1000.0 1800.0 900.0 1800.0 900.0 1600.0 800.0 1600.0 800.0 1400.0 700.0 1400.0 700.0 1200.0 600.0 1200.0 600.0 $/MWH $/MWH MW MW 1000.0 500.0 1000.0 500.0 MW Reduce = 13 800.0 400.0 800.0 400.0 600.0 300.0 600.0 300.0 MW Reduce = 137 400.0 200.0 400.0 200.0 200.0 100.0 200.0 100.0 0.0 0.0 0.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Interval Interval Actual Baseline Reduce HR 17:00 RT Prices Actual Baseline Reduce HR 17:00 RT Prices 32 PUBLIC

Interaction of Price and 4-CP Response Estimated Load Reduction for RTP/BI ESIIDs on Days with Sustained High Prices Esitmated Load Reduction (MW) Average Price ($/MWh) 200 Date 150 3/28/2013 4/4/2013 4/5/2013 9/24/2013 10/1/2013 11/20/2013 12/16/2013 1/6/2014 2/6/2014 2/10/2014 3/3/2014 3/4/2014 3/4/2014 3/24/2014 4/7/2014 4/29/2014 5/30/2014 11/4/2014 11/13/2014 5/18/2015 8/5/2015 8/12/2015 8/13/2015 (25.4) 46.6 108.3 16.8 72.3 (25.6) (22.4) 168.6 3.7 32.1 155.7 156.0 (4.6) (48.8) (13.1) 91.0 51.4 54.4 15.6 12.7 150.8 137.0 114.4 207 239 Load Reduction (MW) 1,203 751 1,215 262 428 4,422 301 648 2,734 2,626 212 273 676 543 313 689 455 729 745 609 798 100 50 - (50) 200 400 800 1,600 3,200 Price ($/MWh) Estimated Load Reduction Regression Estimated Load Reduction 47.5 87.0 110.1 126.5 139.3 149.6 166.0 Price log(Price) Regression Estimates for Selected Price Points 500 2.699 3.000 3.176 3.301 3.398 3.477 3.602 1,000 1,500 2,000 2,500 3,000 4,000 Based on findings thus far, these price responsive MWs are also included in the 4CP response 33 PUBLIC

Questions? ON OFF craish@ercot.com 512/248-3876 34 PUBLIC