1. http://nodal.ercot.com 1 Market Trials DAM/RUC/SASM Weekly Update April 2, 2010

2. http://nodal.ercot.com 2 Antitrust Admonition ANTITRUST ADMONITION ERCOT strictly prohibits Market Participants and their employees who are participating in ERCOT activities from using their participation in ERCOT activities as a forum for engaging in practices or communications that violate the antitrust laws. The ERCOT Board has approved guidelines for members of ERCOT Committees, Subcommittees and Working Groups to be reviewed and followed by each Market Participant attending ERCOT meetings. If you have not received a copy of these Guidelines, copies are available at the Client Relations desk. Please remember your ongoing obligation to comply with all applicable laws, including the antitrust laws. DISCLAIMER All presentations and materials submitted by Market Participants or any other Entity to ERCOT staff for this meeting are received and posted with the acknowledgement that the information will be considered public in accordance with the ERCOT Websites Content Management Operating Procedure.

3. http://nodal.ercot.com 3 Agenda DAM summary for 4/1 QSE Activities for Next Week General Reminders/Updates Environment Report –Planned outages –Known Issues Scorecard reminder Special Topics –Bid/Offer submission efficiencies –Multi-hour blocks for curve submissions Question and Answers / General Discussion Appendix –DAM Kickoff slides ERCOT asks that Market Participants log into the WebEx session using their company name and then their name. This will allow ERCOT to take roll-call offline.

4. http://nodal.ercot.com 4 Submission Overview for Apr 1 Submission overview Overall, 112 QSEs participated

5. http://nodal.ercot.com 5 Submission Overview for Apr 1 Submission overview Energy Bids from QSEs – 120% of Load was requested.

6. http://nodal.ercot.com 6 Submission Overview for Apr 1 Submission overview AS Self-Arrangement from QSEs – 100% of AS Obligation was requested –30 QSEs sent in AS Self-Arrangement –We reduced AS requirement in DAM to ensure no AS was procured –Next DAM will request 50% of AS Obligation to be self-arranged Three-Part Offers – 82% of QSEs submitted prior to the DAM Energy Only Offers – 70 QSEs submitted EOOs PTP Obligation Bids – 37 QSEs submitted an hourly average of ~2000 MW

7. http://nodal.ercot.com 7 Submission Overview for Apr 1 Note: Price report issue after Apr 1 DAM DAM Settlement Point Price report – Due to a database cleanup issue on our side as a result of prior testing, two prices were reported for each settlement point. –We manually reposted the DAM SPP csv file removing the duplicate data around 5 pm yesterday –Awards reports were also affected but cannot be reposted –DAM MCPC report was affected – note that all MCPCs all day were $0 as we did not procure any AS –DAM LMP report not affected –The data issue has already been corrected

8. http://nodal.ercot.com 8 Next week’s Activities DAM executing on 4/6 and 4/8 (Op Days are 4/7 and 4/9) Similar to this week’s activities, except: –Adding AS procurement –QSEs with Resources should submit AS Offers –Self-Arranged AS requested is now 50% –All other guardrails remain the same Remember that Tuesday’s Load Bid MW target is 80% of forecasted load, and Thursday’s is 120%. Week 2 Note: Dates are DAM execution days 4/6/2010 & 4/8/2010 Objective AS co- optimization Network ConstraintsNone Self-Arranged AS Requested50% Load Bid MW Requested 80% Tue/120% Thurs forecasted load Virtual Bids / Offers Up to 5 transactions totaling 50 MW/QSE/hr PTP Obligations Up to 5 bids totaling 50 MW/QSE/hr NOIE CRR Offers Allocated CRRs only COP UpdatesNot needed DRUCNone HRUCNone SASMNone

9. http://nodal.ercot.com 9 General Reminders/Updates ERCOT will run a DAM and DRUC in the market trials environment on 4/2 for internal testing purposes –We submitted DAM transactions to seed the market run so QSEs may receive additional notifications via their listeners Did not submit sany TPOs so as not to interfere with SCED testing –Results will be published but are not supported. Staff will not be available to answer questions about Op Day 4/3. Network Model Update –Last load occurred 4/1 An updated settlement points and MP short name list is posted at http://nodal.ercot.com/readiness/markettrials/index.html http://nodal.ercot.com/readiness/markettrials/index.html –Next scheduled loads are 4/14 and 5/3 Note that the target previously communicated for weekly loads has been moved back. Will follow up when we have a new target date. Phase 5 Handbook for DAM/RUC/SASM was posted on 3/31 –http://nodal.ercot.com/readiness/markettrials/dam/index.htmlhttp://nodal.ercot.com/readiness/markettrials/dam/index.html

10. http://nodal.ercot.com 10 Support Metrics * This week, 16 out of 252 questions were responded to outside of the 24 hour time frame. Market Participant Inbound Questions Last WeekThis Week

11. http://nodal.ercot.com 11 Day-to-day operations summary: Planned / Unplanned Outages Planned Outages –03/29/10 – 03/30/10 06:00 P.M – 06:00 P.M Outbound notifications were turned off as a result of operating day tests conducted on the NPROD environment. Affected notification deliveries associated with MMS and OS submissions. Unplanned Outages –03/26/10 09:00 A.M. – Ongoing Market Manager UI experiencing intermittent periods of unavailability and / or degradation in performance Teams have identified a potential resolution and are working to re-create this in the test environment Work-arounds have been implemented in the Nodal Production environment and have stabilized the issue until a permanent fix is identified –03/31/10 – 03/31/10 Open MPs were unable to access LRS reports via MIS reports page. A defect has been logged and users were provided a workaround for downloading the report. –03/31/10 – 04/01/10 08:00 A.M – 7:00 A.M MPs were unable to access Outage Scheduler UI as result of network firewall block. –04/01/10 – 04/01/10 2:15 P.M – 3.15 P.M Experienced access issues with Market Manager and OSUI applications. Exception occurred as a result of unplanned hardware failover.

12. Environment Report-Known Issues New DAM/RUC/SASM known issues Awards are displaying incorrectly and incompletely on the Market Manager for Energy Only Offers and Energy Bids. Please use the link for ‘Download XML’ to view the full day’s worth of awards http://nodal.ercot.com 12

13. Environment Report-Known Issues New DAM/RUC/SASM known issues Trade confirmation notifications are failing for certain QSEs The trade confirmation notification that follows the cancellation of a confirmed trade is currently returning a verb of ‘created’. This will be changed to ‘canceled’. Market Manager – when entering AS self-arrangement for RRS, you must enter values for RRSGN, RRSLD, and RRSNC, even if that value is zero. The error message is vague if you do not enter all the values, and the fields are not highlighted to show the source of the error. The error returned when submitting an AS self-arrangement for RRSNC that exceeds the 50% limit for RRS from Load Resources references an AS Obligation with 2 significant digits after the decimal. It should only have 1. http://nodal.ercot.com 13

14. Environment Report-Known Issues MIS/reports issues Some QSEs can only see the Load Ratio Share report if they access it through the portlet ‘QSE Forecasts and Load’ on the Day-Ahead Market page, whereas no report is returned if accessed through the Reports and Extracts Index. Please use the portlet until this is fixed. The underlying cause is still under investigation. –Reminder that this report also has an issue with missing hour 0100 DAM LMP, DAM SPP, and DAM MCPC reports posted twice – once at 1230 and once when DAM was complete. The triggers will be fixed. –The extraneous DAM SPP reports were removed when we did the manually reposting discussed earlier Settlement Points and Settlement Points to Electrical Buses Mapping did not post but is targeted to begin posting next week. http://nodal.ercot.com 14

15. Environment Report-Known Issues MIS/reports issues The following Market Information Web Services were turned off until late yesterday: –Aggregated AS Offer Curves –AS Service Plan –Total AS Offers –Total Load (late item from Phase 3) –Total Energy (the associated report is not on – no data) Reminder that the following reports are on hold and are targeted to be delivered with 4/9 release. –NP4-192-CD DAM Total Energy Purchased –NP4-193-CD DAM Total Energy Sold http://nodal.ercot.com 15

16. MP16 Day-Ahead Market Participation  GREEN scores (adequate participation) will light up on 4/7 after two DAM runs.  AMBER/RED scores (inadequate participation) will light up on 4/21 after 6 DAM runs  QSEs will be contacted starting 4/12 if less than 50% participation Nodal Scorecard Reminder http://nodal.ercot.com 16

17. Special Topics Bid/Offer efficiencies ERCOT has identified efficiencies in Bid/Offers submission with regard to the format of submission This applies to all transaction that use a Bid ID or an Offer ID (Energy Only Offers, Energy Only Bids, PTP Obligation Bids, and CRR Offers) Preference is for QSEs to submit the same Bid/Offer ID for each hour in the submission, versus submitting a different Bid/Offer ID for every hour. The market system treats the submission the exact same way, regardless of which way it is submitted This preference is due to system performance, and if most QSEs use the preferred method, more bids and offers can be submitted before DAM sizing limits are exceeded For xml examples detailing this issue, please view a document that will be posted along with this presentation on the calendar page at http://www.ercot.com/calendar/2010/04/20100402-MT http://www.ercot.com/calendar/2010/04/20100402-MT http://nodal.ercot.com 17

18. Special Topics Multi-hour blocks for curve submissions When you submit an Energy Only Offer or an Energy Bid, you have the choice of submitting using fixed, variable or curve types. Further, you can create a multi-hour block that will ensure that your bid/offer is awarded the same quantity for all hours in the block. It was identified that the system cannot handle multi-hour blocks for curve submissions. The functionality was disabled, so if a QSE submits a multi-hour block with a curve indicator, DAM will remove the multi-hour block prior to clearing and QSEs will receive awards of differing quantities for each hour Protocol section 4.4.9.5.1 and 4.4.9.6.1 only calls out multi-hour blocks for fixed and variable submissions Documentation will be updated, and the issue will be discussed at NATF on 4/6. http://nodal.ercot.com 18

19. http://nodal.ercot.com 19 Q&A Q&A / Open Forum

20. Appendix –DAM Kickoff slides –Pre- and post-DAM reports http://nodal.ercot.com 20

21. http://nodal.ercot.com 21 Objectives Objectives of Phase 4.0 DAM/RUC Market Trials: Execute DAM, RUC, and SASM in the Market Trials environment twice a week Generate awards, notifications, and reports

22. http://nodal.ercot.com 22 Entry Criteria ERCOT Entry Criteria for Phase 4.0: ERCOT has completed required integration testing for Phase 4.0 functionality ERCOT has published all known, market-relevant defects to Market Participants via the Readiness Center Market Participant Entry Criteria for Phase 4.0: QSEs have met the system requirements (digital certificate with ‘MMS Trader’ role assigned, etc.) QSEs have completed the qualification testing and have confirmed their ability to use Web Services or the Market Manager to submit transactions necessary to support Day-Ahead Market Trials

23. Summary of QSE Activities QSEs with Resources: Maintain SCED offers and ensure Start-Up and Minimum Generation Offers are available prior to the Day Ahead 10:00 a.m. (Central) deadline Submit AS Offers Update COP after DAM, DRUC, HRUC starting 4/13 QSEs with Load: Self-Arrange requested amount of AS Obligations Bid a portion of their Load in the DAM (see example on next slide). In general, this should take the form of an Energy Bid but during the last week of April, can also be in the form of a PTP Obligation Bid. –Tuesday- 80% of QSE’s forecasted Load –Thursday- 120% of QSE’s forecasted Load http://nodal.ercot.com 23

24. Summary of QSE Activities QSEs with Load (cont’d): Example for load bids All QSEs: May submit a limited amount of DAM Energy Only Offers and DAM Energy Bids that do not represent actual Resources or Loads (virtual bids and offers) – limit is up to a MW quantity total contained within a certain number of transactions per hour. PTP Obligation Bids will be limited as well Details with dates on next slide http://nodal.ercot.com 24

25. http://nodal.ercot.com 25 Schedule/Key Dates Week 1Week 2Week 3Week 4Week 5 Note: Dates are DAM execution days4/1/2010 4/6/2010 & 4/8/2010 4/13/2010 & 4/15/2010 4/20/2010 & 4/22/2010 4/27/2010 & 4/29/2010 Objective Connectivity / Execution AS co- optimization Network constrained + Initial DRUC DAM + DRUC DAM + DRUC + HRUC + SASM Network ConstraintsNone Included Self-Arranged AS Requested100%50% Actual Load Bid MW Requested 80/120% forecasted load 80/120% forecasted load 80/120% forecasted load 80/120% forecasted load Virtual Bids / Offers Up to 5 transactions totaling 50 MW/QSE/hr Up to 10 transactions totaling 100 MW/QSE/hr Up to 10 transactions/ QSE/hr PTP Obligations Up to 5 bids totaling 50 MW/QSE/hr None Up to 5 bids totaling 50 MW/QSE/hr Up to 5 bids totaling 50 MW/QSE/hr (unless the bid represents QSE's load) NOIE CRR Offers Allocated CRRs only None Allocated CRRs only COP UpdatesNot needed After DAM and DRUC After DAM, DRUC and HRUC DRUCNone DRUC Thursday DRUC after each DAM HRUCNone Limited SASMNone Yes

26. http://nodal.ercot.com 26 Activities Market Participant Activities: Submit, update, and cancel DAM submission items, while keeping within the guardrails. –Three-Part Supply Offers (including Minimum Energy Offer and Startup Costs) –COP –AS Offer –AS Self-Arrangement –Energy-Only Offers –Energy Bids –PTP Obligation Bids –CRR Offer (for NOIEs only) Report any issues to the Market Trials Team at markettrials@ercot.commarkettrials@ercot.com Download and review pre-DAM and post-DAM report postings Download and review RUC postings, as applicable Download and review SASM posting, as applicable Update COP (after DAM, RUC) Submit self-selected credit limit to ERCOT, if desired, as often as weekly

27. http://nodal.ercot.com 27 Activities ERCOT Activities: Execute DAM (including Phase 2 Validation), DRUC, HRUC and SASM periodically Generate Awards, Day-Ahead LMPs/SPPs, and other reports Communicate DAM/RUC/SASM reports and outputs to the market via Market Information System (MIS) postings Verify QSE submission activities Work with Market Participants to resolve issues Update Counterparty credit limits with self-selected credit limits submitted by MPs

28. Other Note: All transactions will be supported. Trade submission and confirmation (Energy, Capacity and AS Trades) may be exercised at this time. DAM notifications will be active. Phase 2 Validation process will be active and supported. QSE transactions that do not follow the guidelines are subject to cancellation at ERCOT’s discretion. ERCOT may run DAM on non-supported days. No QSE participation is requested, and ERCOT staff will not be available to answer questions regarding the outputs of these non-supported processes. CRR information from the market trials auction conducted in March for the month of April will be integrated into the market system. CRR Offers (by NOIEs) must contain CRR IDs from this auction in order to be valid. http://nodal.ercot.com 28

29. http://nodal.ercot.com 29 Exit Criteria ERCOT Exit Criteria ERCOT completes DAM execution with Market Participant data, as planned ERCOT completes RUC execution with Market Participant data, as planned ERCOT completes SASM execution with Market Participant data, as planned Market Participant Exit Criteria Each QSE participates in at least 50% of the available scheduled DAM executions by successfully submitting the relevant transactions as tracked on the DAM participation dashboard

30. http://nodal.ercot.com 30 Dashboard

31. MP16 Day-Ahead Market Participation  Requires at least 50% participation in Market Trials Day Ahead Market runs (includes all sub-QSEs)  Metric is reported up to the 168 Hour Test  80% of Load and 80% of Generation participation required to meet the metric  Light up date of 4/1 for GREEN/WHITE and 4/21 for AMBER/RED  Participation equals any DAM-specific transactions (bids, offers, or AS self- arrangements) Nodal Scorecard Reminder http://nodal.ercot.com 31

32. Supplemental Materials Slide 32 Reference and DescriptionLocationVersion External Interfaces Specification http://nodal.ercot.com/readiness/sandbox/index.html1.19 Explanation of Market Submission Items http://nodal.ercot.com/readiness/markettrials/connectivity/in dex.html 0.26 Market Manager User Guidehttp://nodal.ercot.com/readiness/markettrials/connectivity/in dex.html 0.06 MMS Requirementshttp://nodal.ercot.com/docs/pd/mms/index.html#reqVarious Market Connectivity Handbookhttp://nodal.ercot.com/readiness/markettrials/connectivity/in dex.html 0.97 DAM/RUC Known Issues Listhttp://nodal.ercot.com/readiness/markettrials/dam/index.ht ml N/A Web Services XSDshttp://nodal.ercot.com/readiness/sandbox/index.html1.3.19 Sample Reports, Extracts, and DDLs http://nodal.ercot.com/readiness/reports/index.htmlVarious DAM ERCOT Operating Procedures http://nodal.ercot.com/readiness/markettrials/dam/index.ht ml 2.0 DRUC/WRUC ERCOT Operating Procedures http://nodal.ercot.com/readiness/markettrials/dam/index.ht ml 0.2 http://nodal.ercot.com 32

33. http://nodal.ercot.com 33 Report Postings Posted by 6 am: Ancillary Services (AS) Plan Load Ratio Shares (these will be static based on Zonal production data as of October 16, 2009) * AS Obligations * Wind Generation Resource Power Potential (WGRPP) forecast * and Aggregated WGRPP forecast List of all Settlement Points and the mapping to Electrical Buses Load forecasts for ERCOT system, Weather Zones and Load Zones Load forecast distribution factors Distribution Loss Factors and forecasted Transmission Loss Factors Weather assumptions * Denotes MIS Certified reports

34. http://nodal.ercot.com 34 Report Postings Posted after each DAM: Awards (AS Offers, Energy Offers, DAM Energy-Only Offers, DAM Energy Bids, CRR Offers, and PTP Obligation Bids) * DAM Clearing Price for Ancillary Services (MCPC) Day-Ahead hourly Settlement Point Prices (SPPs) Day-Ahead hourly Locational Marginal Prices (LMPs) Shadow Prices Quantity of AS Offers Aggregated AS Offer Curve Total quantity of energy (in MWh) bought and sold in DAM See DAM Handbook for a list of all DAM/RUC/SASM reports available starting in Phase 4.0 - http://nodal.ercot.com/readiness/markettrials/dam/index.html. See MIS Handbook for a comprehensive list of reports available - http://nodal.ercot.com/readiness/markettrials/mis/index.html.http://nodal.ercot.com/readiness/markettrials/dam/index.html http://nodal.ercot.com/readiness/markettrials/mis/index.html * Denotes MIS Certified reports