Austin Energy changed their TOU periods effective April 1st but didn't notify customers until after bills went out. Old schedule had peak from 2-8pm, new schedule is 3-7pm summer and 6-9am + 6-9pm winter. Client has a March 15 - April 14 billing cycle so half the interval data falls under old rates, half under new. Anyone dealt with mid-cycle rate changes? Austin Energy is applying new rates to the entire billing period which seems wrong.
TOU rate schedule changes mid-billing cycle - how to handle interval analysis?
Vanessa, that's a clear billing error. California utilities have strict rules about rate change implementation - they must apply the rate schedule that was in effect when the energy was consumed. You'll need to rebuild the entire bill using both rate schedules for their respective periods. PG&E tried this same nonsense with one of our clients last year.
Gil is absolutely right. Georgia Power actually has good documentation on this - when rates change mid-cycle, they prorate based on the actual consumption dates. You'll need the 15-minute interval data and apply the correct TOU periods to each timestamp. It's tedious but usually results in significant savings. We recovered $8,400 for a client when Southern Company made a similar error.
This happens more than you'd think. Idaho Power changed their Schedule 19 TOU periods in 2017 and screwed up hundreds of bills. The key is getting the exact effective date and time from their tariff filing. Sometimes there's ambiguity about whether the change takes effect at midnight on the first day or at the start of the next billing cycle. That distinction can be worth thousands of dollars.
Warren, good point about the effective time. Austin Energy's tariff says "effective April 1st" but doesn't specify midnight. Their customer service is claiming it applies to bills rendered after April 1st, not consumption after April 1st. That would make the entire March 15-April 14 cycle subject to new rates, which benefits them significantly.
Vanessa, pull the actual tariff filing from the Texas PUC. Utilities sometimes train their CSRs incorrectly on rate implementation. OPPD tried that same interpretation trick with us in Nebraska. The tariff language will clearly state whether it's based on consumption date or billing date. If it says "effective April 1st" without qualification, that means consumption on/after April 1st.
Greg's advice is spot on. Xcel Energy here in South Dakota has very specific tariff language about mid-cycle changes. They prorate to the day, sometimes even to the hour for large customers. The regulatory filing will have the exact implementation methodology. Don't accept the utility's interpretation without seeing the actual tariff text.
I've had three of these cases with AEP Texas in the past two years. They always try to apply the new rate to the entire billing period when it benefits them. The PUC filing specifically requires proration based on actual consumption dates. Build your analysis day by day - it's the only way to prove the correct calculation. Usually saves 15-30% on the disputed month.
Vivian makes a great point about building day-by-day analysis. Alabama Power had a similar issue in 2018 when they changed Schedule LPL. We used Excel to reconstruct each day's charges under the correct rate schedule. The utility initially fought it but eventually agreed when we showed our methodology matched their own tariff requirements. Saved the client $23,000.
Has anyone created a template for these mid-cycle rate change calculations? We're seeing more utilities implement dynamic TOU schedules and this is becoming a regular issue. Would be helpful to have a standardized approach for the interval data analysis and regulatory citations.
UPDATE: Found the PUC filing and you all were right. Austin Energy must prorate based on consumption date, not bill date. They've agreed to recalculate and we're looking at about $4,200 in refunds. Thanks for the guidance everyone - this forum saves us so much research time!
Excellent work Vanessa! Jim, I've been thinking about creating some standard templates for common interval data issues like this. Mid-cycle rate changes, DST transitions, and meter change-outs are the big three we see repeatedly. Might be worth developing some standardized Excel tools that members can share. What do you think?