Working on a large office complex audit here in Austin and finding some strange discrepancies between Austin Energy's TOU billing and what I'm calculating from the interval data. Their new time-of-use periods should be 2-8 PM weekdays for summer on-peak, but the billing seems to be applying on-peak rates from 1-9 PM. Has anyone else seen billing system lag with rate schedule changes? The difference is about $2,800 monthly.
TOU rate analysis - Austin Energy vs interval data discrepancies
Vanessa, I've seen this with APS here in Phoenix when they updated their E-32 schedule. Sometimes the billing system doesn't get updated immediately when tariffs change. Double-check the effective date on the tariff filing versus when your billing period started. Also verify they're using the correct seasonal definitions - some utilities have different summer/winter boundary dates than you'd expect.
Sarah's right about the billing system delays. Ameren here in St. Louis took three months to properly implement their new TOU periods last year. I had to file formal complaints on two different accounts. Make sure you have the official tariff documentation showing the correct time periods. Austin Energy is usually pretty good about fixing billing errors once you show them the math.
Thanks Sarah and Pam. I pulled the official Rate Schedule GS-4 filing and you're absolutely right - the tariff shows 2-8 PM but their billing system is still using the old 1-9 PM window. Called Austin Energy and they admitted it's a programming error affecting about 200 customers. They're issuing credits next month. This is why we triple-check everything!
Great catch Vanessa! This is exactly why interval data analysis is so crucial. CPS Energy had a similar issue in 2014 where their weekend TOU definitions were wrong for six months. Saved my clients over $45K in billing adjustments. Always compare your interval calculations to the actual bill line by line. The utilities aren't perfect.
Final update - got the billing adjustment processed. Total credit was $8,420 for three months of incorrect TOU application. Client bought me dinner and is referring two more properties. Sometimes these billing errors turn out to be the most profitable audits!