ERCOT Staff 2005 AV Residential Update PWG Presentation

1. ERCOT Staff 2005 AV Residential UpdatePWG Presentation August 24, 2005

2. TDSP – ERCOT Residential AV Validation Update • AEP • Change file received, ERCOT and TDSP are in agreement with proposed change file. • CNP • TDSP sends a list of 333,847 proposed changes (ERCOT estimated 190,101 changes). • ERCOT’s initial review indicates dead bands are not being applied correctly, TDSP confirms problem with dead bands, will rerun population • TDSP sends a list of 164,795 proposed changes • ERCOT review of TDSP file finds of the 164,795 changes only 6 ESIIDs were defaulted assignments in 2003 • ERCOT requested entire residential population files to assist TDSP in researching default assignment 2003 discrepancies • ERCOT’s review of TDSP population file finds of the ≈1.6 million ESIIDs, only 119 were default assignments in 2003, and ≈ 65,000 ESIIDs not included in the TDSP population files that ERCOT identified as active or de-energized. • To assist TDSP with research ERCOT provides TDSP with a list of ESIIDs whose assignment in 2003 were not defaulted • TDSP sends list of 169,765 proposed changes

3. TDSP – ERCOT Residential AV Validation Update • CNP – continued • TDSP and ERCOT in disagreement on ≈ 20% of calculated/default flag for 2003 – ERCOT identified numerous ESIIDs with a current load profile of RESHIWR and flagged as a default in 2003. For AV2003 all defaulted ESIID’s should be RESLOWR • TDSP’s research finds over 26,000 ESIIDs that were changed to RESHIWR for unknown reasons after AV03 • TDSP sends list of 168,902 proposed residential changes • ERCOT and TDSP disagreement on ≈ 7% of calculated/default flag for 2003, ERCOT found 301 ESIIDs in file without the calculated/default flag for 2003, TDSP identifies these ESIIDs contain conflicting rate vs. profile and should be removed from change file. TDSP will resend new change files. • ERCOT’s review of proposed change file identifies 501 exceptions and request TDSP to provide usage data. • Nueces • ≈8,000 ESIIDs opted in the market as of August 2005. ERCOT is in the process of confirming ESIIDs and profile assignment loaded into ERCOT systems are in agreement with approved profile.

4. TDSP – ERCOT Residential AV Validation Update • Sharyland • ERCOT assisted the TDSP in performing calculations for the 2003 and 2004 AV with the understanding that they would get a program in place by 2005 AV • ERCOT sent e-mail reminding TDSP that files were due • TDSP sends a list of proposed changes, Calculated/Default field for ‘03 not included in the file. • Sent e-mail requesting the required field to be included, and a new change file submitted • Received files with field labeled “Assn 04” instead of “Assn 03” , requested clarification from TDSP. • ERCOT received file, but ESIIDs in file were not valid. ERCOT request new file. • TDSP sends new files with “Assn 04” still in file and entire population instead of changes only • Sharyland and ERCOT in disagreement on ≈ 26% of calculated/default flag for 2003 • ERCOT and TDSP discussed logic for the calculated/default flag for 2003 • TDSP requested ERCOT provide calculated/default flag for 2003 population • ERCOT provided information to TDSP on 8/18/2005 • ERCOT received proposed change file, ERCOT requested usage for 18 ESIIDs

5. TDSP – ERCOT Residential AV Validation Update • TNMP • TDSP sends file of proposed changes, • ERCOT’s review of files flags a large number of exceptions, requested TDSP provide usage for subset of sampled ESIIDs. • ERCOT receives usage, reran validation with TDSP usage, utilizing TDSP calculated/default flag for 2003 • TDSP and ERCOT in disagreement on ≈ 33% of calculated/default flag for 2003 • ERCOT and TDSP discussed logic for the calculated/default flag for 2003 • TDSP finds they do not have the required information to determine the calculated/default flag for 2003 and requested the information from ERCOT • ERCOT provided TDSP information requested on 8/22/2005 • TXU-ED – note: TDSP changed programmers after AV2005 code testing completed • TDSP sends a list of 272,498 proposed changes • ERCOT’s review of file flags a large number of exceptions, requested TDSP provide usage for subset of sampled ESIIDs. • ERCOT and TDSP identified calendar day problem, TDSP determines leap year problem • TDSP and ERCOT in disagreement on ≈ 20% of calculated/default flag for 2003 • TDSP request ERCOT to provide TDSP with calculated/default flag for 2003 • TDSP sends file of proposed changes 300,586 • ERCOT’s review finds TDSP and ERCOT are in disagreement on ≈11% calculated/default flag for 2003 • TDSP is investigating