1. http://nodal.ercot.com 1 Cutover Update Weekly Update October 15, 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 Full Market Trials Agenda General Updates and Reminders Special Topics Nodal Cutover Update Question and Answers / General Discussion 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 General Updates / Reminders

5. http://nodal.ercot.com 5 General Updates and Reminders Monday Market Call will be canceled for 10/18/2010

6. 6 24-Hour Test Reminders 24-Hour Full-System Test –ERCOT will conduct the 24-Hour Test from 10/27/2010 (12pm) to 10/28/2010 (12pm) –ERCOT will send a Market Notice 2 hours prior to the test start to confirm start time –Details for the WebEx that will be held during the test will be sent to Nodal PMs shortly after the Market Notice 24-Hour Full-System Test Scenarios: –Scenario #1: Switch control to the Austin facility During this scenario, ERCOT will switch control from Taylor to Austin for approximately two hours –Scenario #2: Simulate EMS Failure During this scenario, ERCOT will: –Discontinue sending Regulation Service deployments and updated UDBPs and SCED Base Points »To stop Reg. deployments and updated UDBPs, ERCOT will place the LFC application in “monitor” mode »To stop updated SCED Base Points, ERCOT will activate Emergency Base Points with an incremental deployment of 0 MWs –Request specific QSE(s) to go on Constant Frequency Control This scenario will be initiated at an unannounced time during the 24-Hour Test window This scenario will be conducted for approximately 15 to 30 minutes

7. http://nodal.ercot.com 7 Special Topics: Follow-up Items from MRS

8. 8 MRS Follow-Up Item: SE Reports Status EMIL_IDPRODUCT_NAMEFIRST_RUN_DATE NP1-116State Estimator Standardsavailable NP3-363-ERState Estimator Bus Telemetry Accuracy Report1/3/2011 NP3-578-ERState Estimator Convergence Rate Report1/3/2011 NP3-579-ER MW Residuals - SE vs RTCA Base Case - for Congested Transmission Elements Report1/3/2011 NP3-580-ER MW Residuals - SE vs Telemetry for Congested Transmission Elements Report1/3/2011 NP3-581-ER MW Residuals - SE vs Telemetry for Major Transmission Elements Report1/3/2011 NP3-582-ERKV Residuals - SE vs Telemetry - for Key Buses Report1/3/2011 NP6-619-CDState Estimator Transmission Flows and Voltagesawaiting PUCT decision NP6-620-CDState Estimator 15-minute Average of Loads11/30/2010 NP6-621-CDState Estimator Load Report - Individual Load on Electrical Busesavailable NP6-622-CDState Estimator Transformer Informationawaiting PUCT decision NP6-623-CDState Estimator Load Report - Load by Electrical Bus by Load Zoneavailable NP6-624-CDState Estimator Load Report - Total System Load on Electrical Busesavailable NP6-625-CDState Estimator Load Report - Total ERCOT Generationavailable NP6-626-CDState Estimator Load Report - DC Ties Flowsavailable NP6-93-CDState Estimator Switch Status11/30/2010 NP8-365Monthly Telemetry Point Availability Statistics Report3/17/2011

9. http://nodal.ercot.com 9 Load Resources Question: “After Nodal Go-Live, what if I have no ability to split up my Load Resources into the Group 1 & Group 2 assignments?” Answer: Based on Nodal Protocols 6.5.9.4.2.2.a.ii.A, “QSEs shall deploy Load Resources according to the group designation and will be given some discretion to deploy additional Load Resources from Group 2 if Load Resource operational considerations require such.” In other words, if a QSE has Load Resources that are physically dependent on each other, but they are split between Group 1 and Group 2, that QSE has the option to deploy the those Load Resources at the same time.

10. Dashboard currently in MIS –System Ancillary Service Capacity Monitor –SCED Up/Down –Day-Ahead & Real-Time LMPs Only one LMP at a time –LMP Ticker –Frequency expanding scope to include DC Tie and Other Real-Time data (similar to zonal real-time display) Later delivery – LMP Contour Map (data and display issues) – for go-live –Load Forecast vs. Actual (data alignment issue) – for go-live –DC Ties (combine into freq and delete) –Weather (not in current scope for go-live) New scope –Adding 4 new reports (similar to MOS public of pricing tables) –Turned on links on ERCOT.com to Real-Time and Day-Ahead http://nodal.ercot.com 10 MIS Dashboard Update

11. Addition of mospublic-like displays being considered - Never in any requirements AS Prices 15-min RTM Settlement Point (96 rows) Day-Ahead Settlement Point (24 rows) Real-Time LMPs (most recent 20 SCED runs) Operation Day, IntervalEnding, LZ_Houston, LZ_North, LZ_South, LZ_West, LZ_AEN, LZ_CPS, LZ_LCRA, LZ_RAYBN, HB_BUSAVG, HB_HUBAVG, HB_Houston, HB_North, HB_South, HB_West “Screen Scraping” is not supported by ERCOT All prices are available via Web Services or CDR reports http://nodal.ercot.com 11 Additional Dashboards

12. DAM Failure Scenario DAM Failure scenario to be executed on Oct 21 –Please have resources available to resubmit your Self-Arranged AS into the SASM once it opens around 1800. Sequence: –DAM Operators will abort the DAM and declare an Emergency Condition. This notice will be issued to QSEs no later than one hour before the start of the SASM. This notice will contain the target time for the start of the SASM. –QSEs will have the opportunity to submit/change AS Offers to be used in the upcoming SASM – no caps will be in place on these offers other than SWCAP. –No DRUC –ERCOT will open the SASM in the adjustment period to procure the entire AS Plan. –QSEs resubmit their Self-Arranged AS (the DAM submission will no longer apply) within the 30-minute SASM submission window. –ERCOT executes the SASM and posts the results. http://nodal.ercot.com 12

13. Go-live credit exposure in DAM Proxy prices to be used for purposes of calculating DAM credit exposure for go-live is covered in Protocol Section 4.4.10(8) Implementation: –DAM historical settlement point prices Import hourly average of zonal MCPEs over the last 30 days as a proxy –SCED historical settlement point prices Import 110% of zonal MCPEs over the last 30 days as a proxy for Real-Time SPPs (this ensures the 10% Day-Ahead/Real-Time price difference called out in 4.4.10(b)). –As nodal data is created, the zonal data will roll off, so that 30 days after go-live, all prices used for credit exposure calculations will be nodal prices. http://nodal.ercot.com 13

14. http://nodal.ercot.com 14 Special Topics: Recap of Cutover Activities

15. Market Readiness Seminar Cut-Over Monthly Outlook – Go-Live Sequence of Events DateActionComments 11/15/2010 – 11/29/2010 ERCOT Initiates “Soft Start” to Nodal Market Go-Live ERCOT will run non-binding DAM, RUC daily per Nodal protocol timelines. RTM will remain Open Loop, but continue to publish base points and LMPs. Note that credit will be set high on 11/15 11/15/2010 Credit posts ACLs and TPEs for non-binding DAM First Credit Operating Day 11/16/2010 11/17/2010 Market now able to submit transactions for first Nodal Operating Day (T-14d) 12/01/2010 Operating now available for Market submissions 11/23/2010 QSEs with Resources required to submit 7 days of rolling COPs 12/01/2010 required on 11/23/2010 11/28/2010 2:00 PM – 11/28/2010 3:00 PM Generation and Frequency Control switched to Nodal systems QSEs will begin following Nodal base points Settlements will continue to be Zonal 11/28/2010 2:00 PM – 11/30/2010 11:59:59 QSEs remain on Nodal Control while settling Zonaly 11/29/2010 Last Non- Binding DAM for operating day 11/30/2010 01 October 2010

16. Market Readiness Seminar Cut-Over Monthly Outlook – Go-Live Sequence of Events 01 October 2010 TimeActionComments up to 10:00Bids and Offer submission QSE submit bids and offers 10:00Close DAM 10:00Execute Dam Clearing Process 13:30Approve DAM resultsDay Ahead results posted to MIS 1330-1430Submit COP updates 14:30Close for RUC 14:30Begin Execution of DRUC 16:00Approve DRUC Results 16:00Post DRUC Results 18:00HRUC Begins Hourly Runs 11/30/2010 Go-Live Sequencing

17. Market Readiness Seminar Cut-Over Monthly Outlook – Go-Live Sequence of Events 01 October 2010 Key Zonal Notes for 11/30/2010 and 12/01/2010 –QSEs will maintain: Balancing Energy Offers through Operating Day 12/01/2010 –Submitted on 11/30 for OD 12/1 Resource Plans through Operating Day 12/01/2010 –Maintained continuously through 12/01 to reflect actual Resource Plan Zonal Outages effective on Operating Day 12/01/2010 –Examples: Actual Start / End, Forced Outages, etc –On 11/30/2010 ERCOT will run: Zonal Ancillary Service Market –Zonal awards will be published Zonal RPRS –Run as a study only –Zonal commitments will not be published –Zonal prices will not be generated for 12/01/2010 –No Zonal Submissions or Markets for Operating Day 12/02/2010 or later

18. http://nodal.ercot.com 18 Special Topics: Credit

19. Topics TCR and CRR Credit Limits –Unsecured credit –TCR collateral disposition December 2010 TCR and CRR Auction Overlap December 2010 CRR Auction Specifics Preliminary Credit Cutover Timeline Soft start – credit approach –First Priority Security Interest Approach for estimating initial exposure in CMM Counter-Party Authorized Reps Market Readiness Seminar October 14, 2010

20. TCR and CRR Credit Limits Unsecured credit for TCR Auction –Total unsecured credit limit was set as of Oct 1 –EAL calculated from the October 21 st Zonal Invoice will be used to determine Zonal exposure –ERCOT will notify TCR Account Holders of how much unsecured credit is available for TCR auction by October 25 th (Total unsecured less QSE exposure) Unsecured credit for CRR Auction –Total unsecured credit limit was set as of Oct 1 –EAL calculated from the October 28 st Zonal Invoice will be used to determine Zonal exposure –ERCOT will notify CRR Account Holders of how much unsecured credit is available for TCR auction by November 1st (Total unsecured less QSE exposure) Market Readiness Seminar October 14, 2010

21. TCR and CRR Credit Limits TCR Collateral Disposition –IMPORTANT REMINDER – TCR collateral “goes away” after the last TCR Auction Invoice is paid since TCRs are not referenced in the Nodal Protocols Guarantees or LCs currently in place for TCR auctions cannot be used for Nodal activity, including CRR auctions –Language in those documents is specific to TCRs and retires with TCRs –CPs should plan to replace (if they are not already) these collateral documents with collateral valid for Nodal (including CRRs) »ERCOT will notify those that have these forms of collateral; however, each CP should double check internally about what is needed –Note: Guarantees and LCs held for QSE activity ARE valid for Nodal activity, including CRRs, as well as QSE activity Cash collateral can be refunded or transferred to the Nodal collateral pool upon request –Send requests to ercotcredit@ercot.comercotcredit@ercot.com Market Readiness Seminar October 14, 2010

22. December 2010 TCR and CRR Auction Overlap ERCOT will offer a December 2010 TCR Auction in addition to the December 2010 CRR Auction –The TCR Auction will occur prior to the CRR Auction –Collateral requirements for Auctions TCR collateral will be posted as it has historically been CRR collateral will be posted separately (similar to TCR collateral) for the December 2010 CRR auction (see later slides) –The calendar activities for the Auctions overlap such that TCR Auction invoices are published prior to collateral being required for the CRR Auction but due to be paid after the CRR Auction lock date Note: There are 3 business days between when TCR Auction invoices are published and the CRR Auction lock date –The overlap in activities is unavoidable given time constraints. Of course, participation is not required in either Auction. Market Readiness Seminar October 14, 2010

23. December 2010 TCR and CRR Auction Overlap –Counter-Parties(CPs) who desire to participate in both auctions have several options for managing their collateral during this period Post collateral for the TCR auction and separately for the CRR auction –Disadvantage – may have to post higher levels of collateral for a period of days to accommodate both auctions Prepay their TCR invoice before the CRR Auction lock date and roll cash collateral to the CRR auction –Advantage – avoid “doubling up” on collateral requirements for TCR and CRR auctions –Reminder: Only TCR cash collateral can be “rolled over” Reduce collateral held for TCR invoice to invoice amount and roll collateral to the CRR auction Market Readiness Seminar October 14, 2010

24. December 2010 CRR Auction Specifics As discussed in August and September, the initial CRR Auction (for December 2010) held in early November, will be handled as follows: 1.Treated similarly to the current Zonal TCR Auctions 1.Separate collateral posted 2.If participating in both the TCR and CRR Auction, CP will need to coordinate collateral between the two auctions 2.Process 1.CPs will be notified of the unsecured credit available by November 1 2.To the extend additional credit is desired, CP must send collateral specifically earmarked for the December 2010 CRR Auction to ERCOT via wire transfer between October 28 and November 8 3.The combination of posted collateral and unsecured credit allocated by the CRRAH will be the ACL provided for the CRR Auction 3.Available Credit Limits (ACL) viewable in CRR, not MIS ACLs will be viewable in the CRR Application beginning October 29, 2010 ACLs will be viewable only by CRR Account Holders and Counter-Parties and only in the CRR Application leading up to the December CRR Auction (e.g. CMM is in cutover and Credit Reports will not be available on MIS). Market Readiness Seminar October 14, 2010

25. December 2010 CRR Auction Specifics Release of CRR collateral / Ongoing collateral requirement for CRR obligations The CRR Auction will be complete at the same time as the “soft start” of the Nodal market Once the CRR Auction is complete, –CRR inventory will be transferred to CMM (in conjunction with soft start) –CRR Auction invoices will be reflected in TPE in the Credit Reports until paid –Once the CRR Auction Invoice is paid, excess CRR collateral may be refunded, upon request, with the following consideration CRR Obligations will be collateralized in CMM (in conjunction with soft start) as required per Nodal Protocols Market Readiness Seminar October 14, 2010

26. Preliminary Credit Cutover Timeline Credit Assumptions For the soft start, ERCOT will calculate Total Potential Exposure (TPE) using a) Zonal data and b) binding Nodal data. No non-binding Nodal data will be included in the soft start TPE calculations. Collateral included will be actual collateral held. (details to follow in coming slides) –At this point in the process, CPs should be working within real credit constraints preparatory to Go Live Given that the data used in the soft start TPE calculations is binding, ERCOT will use CMM exposures published beginning November 18 th for BOTH a) the “soft start” period of Nodal and b) as the bases for binding Zonal collateral requirements Market Readiness Seminar October 14, 2010

27. Preliminary Credit Cutover Timeline ERCOT came to this decision based on the following: –The calculations in CMM using Zonal data produce substantially similar results to what is currently experienced in Zonal –Exposure for binding Nodal activity prior to December 1, 2010 should be collateralized. CMM is the most efficient way to accomplish this –Making the change for credit effective November 18 th will allow both ERCOT and Counter-Parties time to work through any issues before the remainder of the market starts up –Making the change for credit effective November 18 th will reduce the confusion as to which set of reports (Zonal vs Nodal) to use between November 15 th and November 30 th Market Readiness Seminar October 14, 2010

28. Preliminary Credit Cutover timeline Thursday, November 11 th –Zonal invoice published –NOTE - last Zonal EAL credit calculation from which a collateral call will be made (system will be maintained through Go Live and will be available for a period beyond Go Live) The Zonal Invoice published on November 18 th will be captured in CMM and Zonal collateral calls will be made based on exposure calculated in CMM using a) Zonal and b) binding Nodal data Monday, November 15 th –Initial DAM run in “soft start” - without CMM credit constraints “e” factors set at 1/0/1 –Initial “soft start” TPE published TPEs in the “soft start” reflect real exposure and collateral only – no non-binding data will be included Non-binding - No collateral calls sent based on these calculations. However, TPE will be binding on November 18 th, so CPs should plan to cover any deficit quickly –Initial “soft start” ACL sent to CRR and DAM Tuesday, November 16 th –Initial DAM run in “soft start” – with CMM credit constraints Market Readiness Seminar October 14, 2010

29. Preliminary Credit Cutover timeline Thursday, November 18 th –Zonal invoice published –NOTE: CMM calculation of TPE will be used as a) the basis for the soft start Nodal ACL and b) the binding Zonal credit calculation from which a collateral call will be made The Zonal Invoice published on November 18 th will be captured in CMM and Zonal collateral calls will be made based on exposure calculated in CMM using a) Zonal and b) binding Nodal data From this point forward, ERCOT will use the CMM calculation of TPE as the basis for determining credit exposure for both Zonal and Nodal Saturday/Sunday, November 20 th – 21 st –CMM calculations will run, Credit Reports will be published and ACLs will be sent to CRR and DAM on non-business days Thursday - Sunday, November 25 th - 28 th – Thanksgiving holiday –CMM calculations will run, Credit Reports will be published and ACLs will be sent to CRR and DAM on non-business days Market Readiness Seminar October 14, 2010

30. Preliminary Credit Cutover timeline Monday, November 29 th –Zonal invoice published –Send ACL for initial binding DAM (afternoon) Tuesday, November 30 th –Initial binding DAM “e” factors set at 1/0/1 Wednesday, December 1 st – “Go Live” Market Readiness Seminar October 14, 2010

31. Approach for establishing the initial exposures in CMM Nodal Soft start beginning November 15 th Zonal binding collateral requirements beginning November 18 th During this period – ERCOT will publish Credit Reports and send ACLs daily based on data that Includes –Actual collateral held (including CRR collateral, excludes TCR collateral) –Zonal data to establish TPE’s (see next slides for details) –Binding Nodal activity CRR inventory from December 2010 auction will impact FCE component –(e.g. Obligations will be collateralized at the greater of the ACPE component of the FCE calculation and the Auction Clearing Price (ACP)) CRR Auction invoices will be reflected in CMM until paid –First Priority Security Interest to the extent executed and perfected Excludes –Non-binding Nodal activity resulting from soft start (e.g. DAM results, RT activity, etc) Market Readiness Seminar October 14, 2010

32. Approach for establishing the initial exposure in CMM Market Readiness Seminar October 14, 2010

33. Approach for establishing the initial exposure in CMM Market Readiness Seminar October 14, 2010

34. Approach for establishing the initial exposure in CMM Market Readiness Seminar October 14, 2010

35. Counter-Party Contact information Reminder – If you haven’t already, please complete the Notice of Change of Information (NCI) form to designate an a) Authorized Representative and also a b) Backup Authorized Representative for your Counter-Party (overall rather than for a specific QSE or CRRAH) –Market Notice went out on September 13, 2010 –ERCOT will contact these designated individuals along with the credit contacts for credit purposes such as collateral calls, late payment notices and breach or default notices. Market Readiness Seminar October 14, 2010