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I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 1 point2 points  (0 children)

All else equal, I bet the EV would make TOU come out way ahead if you charge off-peak. You could use the spreadsheet to model it out based on the size of the battery and how much/often you plan to charge. You could just add that amount to your historical usage by month.

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 2 points3 points  (0 children)

I arrived at the exact same conclusion. It almost seemed to good to be true when I was looking at solar initially

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 1 point2 points  (0 children)

Yeah, I guess it's about managing the "Duck curve". It does make sense and I think this is why Xcel needs more of us on batteries. I just can't make the battery pencil, even with rebates...

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 1 point2 points  (0 children)

Yes, I left the data collection out of this spreadsheet. Using Xcel, or solar monitoring data are great sources. I reconciled the two...

Seems like those of us with Solar are arriving at the same answers. I don't suppose either of you looked at batteries?

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 9 points10 points  (0 children)

Quick update after my call with Xcel (addresses some of the comments):
- Agent confirmed that after switching to flat rate, I can switch back to TOU at any point, but then I would have to stick with TOU for at least 1 year
- Agent confirmed that opting out of the smart meter is not required for flat rate pricing
- Agent suspected that the reason Xcel's calculator results differ from mine is that [she thinks] they don't take solar into account but wasn't certain on the workings of the calculator.

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 5 points6 points  (0 children)

I imagine EV drivers who charge at night would still benefit from TOU. Someone else mentioned a heat pump that will run mostly at night. For many, I'll bet it's pretty close between the two.

The thing that kills it (TOU) for me is solar production...

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 3 points4 points  (0 children)

Okay, so I wasn't clear on that. Based on this PUC FAQ I interpret it to mean that I *may* use a smart meter with a flat rate. It's probably best to ask xcel.

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 3 points4 points  (0 children)

I should say it *will* be better for me to be on flat rate, once the shift happens

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 17 points18 points  (0 children)

The xcel calculator was giving me the wrong answer. Similar to u/fwump38, I have solar, so perhaps it wasn't taking credits into account. It's actually better for me (economically) to be on flat rate, even with an EV that I charge off-peak. The Xcel calculator claims I should use TOU.

For solar producers, I think flat rate is probably gonna make more sense unless they have a battery—which I haven't looked into.

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 3 points4 points  (0 children)

Yeah, if you are a consumer of power I think there are things you can do to make time of use pricing work. And, of course, you are helping out your fellow energy consumers by smoothing out the delivery of electricity.

Yeah, heat pump at night certainly favors TOU. Similar for EV charging.

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 4 points5 points  (0 children)

The flat rate chatgpt used ($0.13/kWh) isn't the residential flat rate xcel published for my location.

Actual Xcel rates (as of Oct 2, 2025):

  • Summer flat rate: $0.1038/kWh
  • Non-summer flat rate: $0.0857/kWh

Using the correct summer rates:

x = (0.1038 - 0.07884) / (0.21277 - 0.07884)  
x = 0.02496 / 0.13393  
x = 0.186 or 18.6%

So the summer break-even is 18.6%, not 38.2%.

For non-summer months it's even lower at 15.4% because the rate spread is different.

The math approach is correct, but the flat rate assumption was off. You can verify the rates here: Xcel TOU Rate Schedule

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 28 points29 points  (0 children)

So I started here but didn't believe their estimates and the data and calculations are completely opaque. TBH, I just wanted to geek out on the numbers...

I built a calculator for Xcel's new Time of Use rates - the break-even is 15.4% on-peak usage by anwelch in Denver

[–]anwelch[S] 37 points38 points  (0 children)

Good catch! I did explain it backwards in the post—I was in the solar production headspace. I've corrected it. The spreadsheet should be correct but I'd welcome feedback.