I've been auditing Xcel Energy bills for a Minneapolis client with rooftop solar on their TOU-R rate schedule. Found some concerning discrepancies in how they're crediting the excess generation during peak hours. The system shows 2.3kW going back to grid during 3-8pm peak period but credit is calculated at off-peak rate. Anyone else catching this type of error with Xcel?
Xcel Energy Time-of-Use with Solar - Finding Billing Errors
Christine, I've seen similar issues with Indianapolis Power & Light here in Indiana. The key is understanding exactly when their peak periods start and end. Some utilities have different peak definitions for net metering vs. regular TOU billing. What time periods is Xcel using for peak credits?
Up in Idaho with Idaho Power, we've had success getting these TOU crediting errors fixed by filing formal complaints. The key is having interval data that clearly shows when excess generation occurred. Christine, are you working with 15-minute interval data or just monthly net readings?
Warren's right about the interval data. Here in Nebraska with OPPD, I caught a $180 monthly error on a commercial solar account by comparing their production monitoring system to the utility's interval billing. The utility was shifting some peak period generation to off-peak buckets.
Good point about the interval data. I have hourly data from the customer's monitoring system and Xcel's smart meter data. Clear mismatch between peak period generation (2:30-6:30pm) and the credits being applied. Peak rate is $0.1847/kWh but they're crediting at $0.0892/kWh off-peak rate.
Christine, that's almost a $0.10/kWh difference! On a decent solar system that could be $50-100+ per month in lost credits. I'd definitely file a billing dispute with Xcel. In Kentucky with KU, we had similar success rate getting TOU solar credits corrected when we had solid data backing up the claim.
Mike's math looks right. That kind of error adds up fast over a year. Linda from Milwaukee here - We Energies had a software bug in 2015 that was doing the exact same thing to TOU solar customers. Took 8 months to get it fixed but customers got full back-credits. Don't let Xcel drag their feet on this.
Down in Texas with CPS Energy, I learned to always request the utility's tariff interpretation in writing when dealing with TOU solar billing. Forces them to clearly state their methodology and makes it easier to challenge if they're wrong. Corpus Christi has pretty good solar resources so this comes up often.
Vivian makes a great point about getting their interpretation in writing. Here in Cincinnati with Duke Energy, I always ask for written clarification on complex rate schedules. Helps prevent them from changing their story later when you find errors. Also creates a paper trail for regulatory complaints if needed.
Update: Filed the billing dispute with supporting interval data. Xcel acknowledged the error and credited back $347 for the past 6 months. They claim it was a meter reading system glitch that affected about 200 TOU solar customers. Thanks everyone for the advice!
Excellent outcome Christine! That's why this forum is so valuable - collective experience helps us all catch these errors faster. I'm definitely going to check my Rapid City solar clients more carefully for TOU crediting issues. Great work getting that resolved.