1. Retail Workshop ERCOT Nodal Update October 06, 2010

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. Agenda Readiness Update Cutover Schedule Q&A Market Testing Activities During Cutover

4. Nodal – Overall Readiness Readiness Signoff ERCOT Management Signoff 10/01/10Complete NATF Recommendation for TAC 10/05/10Complete TAC Approval 10/07/10 BOD Approval 10/19/10 30 Day Market Notice 10/23/10 10 Day Market Notice 11/13/10 4

5. Nodal Cutover and Market Transition – Key Cut-Over Milestones Key Cut-Over Milestones Network Model Nodal Protocol Section 3.10 goes into effect (Sept. 1) TAC Approval – July 1 (July 20) Board Approval – July 20 Market Notice – July 30 Congestion Revenue Rights Nodal Protocol Section 7 goes into effect (Oct. 13) TAC Approval – August 5 Board Approval – August 17 Market Notice – September 13 Outage Scheduler Nodal Protocol Section 3.1 goes into effect (Nov. 1) TAC Approval – August 5 Board Approval – August 17 Market Notice – October 1 Full Nodal Operations Nodal Protocol Sections 3, 4, 5 and 6 go into effect as well as all other unimplemented Protocol Sections (Nov. 23) TAC Approval – October 7 th Board Approval – October 19 th Market Notice – October 23 rd 5

6. Activities Completed (08/01) Model: Begin network modeling timelines-Complete (08/13) OS: Outage Scheduler Zonal to Nodal Import process run (08/13) CRR: Last day to register for CRR December monthly auction (08/16) OS: ERCOT releases Outage Scheduler to Market (08/16-09/17) OS: Open to Market Participants (09/01) Model: Network Model Go-Live (09/01) Model: Deadline to submit Model changes for Month of December (09/02) Model: Begin interim update process (09/01) CRR: ERCOT publishes CRR Activity Calendar to MIS (09/08) CRR: Deadline for PCRR NOIE Contract Eligibility (09/17-12/01) OS: Dual entry of Outages in Zonal/Nodal Systems until Zonal Retirement (12/03/2010) Cut-Over Timeline – Completion to date 6

7. Impacts CRR Test Data from Market Trials will be removed MIS UI and EWS Get Report unavailable from 10/03-10/11 for production reconfiguration** Functional Area Network Model Outage Scheduler Congestion Revenue Rights Credit MIS MayJuneJulyAugSeptOctNovDec Cut-Over Monthly Outlook – October Key Cut-Over Activities for October 2010 (10/01) CRR: CRR system data clean up for Go-Live (10/01) Credit: ERCOT assesses each CPs credit worthiness for the Dec CRR Auction (10/02) OS: First pull of December Outages for CRR Network Model (for PCRR Allocation) (10/02) Model: Network Model built for CRR Allocation and Auction (10/03-10/11) MIS UI and EWS Get Report function not available (ERCOT back end reconfiguration) (10/13) OS: Changes to December Outages considered for CRR Auction Model (10/13) Model: Changes to Model considered for CRR December Auction 7

8. Impacts CRRAH able to retrieve ACLs from CRR system each business day. MPs can post additional collateral until 11/08/2010 for Dec 2010 CRR Auction Dec 2010 CRR Model available on MIS Dec 2010 Monthly Auction Notice available on MIS Functional Area Network Model Outage Scheduler Congestion Revenue Rights Credit MIS MayJuneJulyAugSeptOctNovDec Cut-Over Monthly Outlook – October Key Cut-Over Activities for October 2010 (10/14-10/19) CRR: ERCOT begins accepting PCRR Nominations for December Monthly Auction (updated) (10/15-11/15) Model: Network Operations Model posted to TSP Citrix location and TSPs begin validation process (10/26) CRR: ERCOT shall allocate PCRRs to NOIEs for the 2010 December Monthly Auction and publish to MIS (10/26) CRR: ERCOT shall post CRR Network Model for the 2010 December Monthly Auction to MIS (10/28-11/08) Credit: ERCOT posts ACLs daily for CRR December monthly auction to CRR (10/29) CRR: ERCOT to post December 2010 Monthly Auction Notice to MIS 8

9. Impacts Available Credit Limit is locked for CRRAHs CRRAHs can submit disputes against CRR Auction Invoice via the API or MIS CRRAHs can receive postings on MIS QSEs can begin DAM Bid submission (15 submission items) Market checkpoint calls begin to facilitate issues and readiness Daily Market Conference Bridge starts 11/23 Functional Area Settlements Credit Congestion Revenue Rights Disputes Market Management MayJuneJulyAugSeptOctNovDec Cut-Over Monthly Outlook – November Key Cut-Over Activities for November 2010 (11/8/2010 12:00pm) Credit: Collateral Posting Deadline (Dec Auction) (11/8/2010 5:00pm) CRR: Credit Lock for Dec CRR Auction (11/9/2010 – 11/11/2010) CRR: December CRR Auction Bid Open/Close (11/12/2010) CRR: December CRR Auction Executes (11/15/2010) CRR: December CRR Auction Results published (11/16/2010) Settlements: December CRR Auction Invoice published (11/16/2010) Disputes: Dispute submitted to ERCOT for CRR Invoice (11/19/2010) Credit: Payment Due for December CRR Auction Invoices (11/22/2010) Settlements: Payments to CRRAH (Dec Auction) (11/23/2010) Credit: ERCOT to Release ACL (TPE and ACL Reports Available on MIS) (11/23/2010) Market Submission Opens (Remaining Protocol Go- Live) (11/24/2010) Model: Network Model Load (11/29/2010) Credit: ERCOT to Publish ACL for the initial Day-Ahead Market execution by ERCOT 9

10. Impacts Daily Market Calls continue for issue facilitation Settlement Calendar Extracts (See Emil for full list of postings) MPs receive 1 st Nodal Invoice for DAM and RTM via MIS MPs can submit Disputes via MIS or API Functional Area Network Model Settlements Congestion Revenue Rights Credit Market Management System MayJuneJulyAugSeptOctNovDec Cut-Over Monthly Outlook – December Key Cut-Over Activities for December 2010 (12/01/10) Nodal Program: Nodal Go-Live (Operating Day 1) (12/3/2010) Settlements: Nodal Day Ahead Market Statement & Invoice Available (12/3/2010) Disputes: Disputes submitted to ERCOT for DAM Invoice (12/8/2010) Credit: Nodal Payment Due for OD12/01/2010 (12/9/2010) Credit: Nodal Payout for OD12/01/2010 (12/15/2010) Model: Network Model Load (12/13/2010) Settlements: Nodal Real-Time Statement Available (12/16/2010) Settlements: Nodal Real-Time Invoice Available (12/27/2010) Credit: Nodal Payment Due for Real-Time Invoice 12/16/10 (12/28/2010) Credit: Nodal Payout for Real-Time Invoice 12/16/10 10

11. 11/30/2010 Go-Live Sequencing Cut-Over Outlook – Go-Live Sequence of Events TimeActionComments up to 10:00Bids and Offer submission QSE submit bids and offers 10:00Close DAM 10:00Execute Dam Clearing Process 13:30Approve DAM results Day Ahead results will be posted to MIS 14:00 Generation Cutover to Nodal Control Generation control moves to Nodal systems 1330-1430 Submit Post DAM COP and offers QSE submit Post Dam COPs and Offers 14:30Close for RUC 14:30Begin Execution of DRUC 16:00Approve DRUC Results 16:00Post DRUC Results 18:00HRUC executions Hourly HRUC runs hourly thru 23:59:59 of Operating Day 11

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13. 13 Market Testing Activities During Cutover (October) October 1, 2010 through October 11, 2010: ERCOT will be performing system maintenance and verifications of production systems Exceptions to this outage are as follows: Outage Scheduling NMMS Telemetry October 11, 2010 through October 17, 2010: ERCOT systems will be available, but no markets or scheduled events will occur during this period October 18, 2010 through October 30, 2010: ERCOT will be performing the following Market Facing Tests Day Ahead Market runs DRUC and HRUC runs SCED will publish LMPs and base points every five minutes during this period Additionally: October 27, 2010 through October 28, 2010 Full System Market and Reliability test will take place for a total of 24 hours 13

14. Market Testing Activities During Cutover (November) November 23, 2010 through November 29, 2010, Non-Binding: Day Ahead Market, HRUC and DRUC per protocol timelines SCED will continue to publish base points and LMPs Note that this testing will occur in parallel to the open submission window for the first binding Operating Day in Nodal (12/1/2010) Note that ERCOT is evaluating the request from the Market to start this November testing as early as November 15, 2010 Note that Settlements, CRR Ownership, Credit and Outages will not be integrated into this test ERCOT may “stub” this data as a close representation of what MPs might expect to see These systems will be focused on their transition to Go-Live plans 14