Back in late 2012, I switched to a time-of-use billing schedule for my electric service with NV Energy (now part of Mid-American, a Warren Buffett joint). I was eligible for a cheaper time-of-use rate because I own an plug-in electric vehicle, allowing me to get deeper discount rates from 10PM to 6AM each day for the entire meter (not just EV charging). Around the same time I also installed Nest thermostats that include a number of features that save me electricity during the hot summer months when the time-of-use rate is at its highest (33.4c/kWh).
The price structure and time schedule is:
- Winter: October 1 through May 31; Off Peak: 5.0c/kWh (10PM-6AM), On-Peak: 5.5c/kWh (6AM-10PM)
- Summer: June 1 through September 30; Off Peak: 6.9c/kWh (10PM-6AM), Mid-Peak: 7.6c/kWh (6AM-1PM and 7PM-10PM), Peak: 33.4c/kWh (1PM-7PM)
| Billing Month | On-Peak | Mid-Peak | Off-Peak | TOU $ | Flat rate (11.7c) $ |
|---|---|---|---|---|---|
| November | 652 | 0 | 491 | $54.20 | $133.73 |
| December | 815 | 0 | 572 | $65.92 | $162.28 |
| January (Est.) | 418 | 0 | 286 | $33.48 | $82.37 |
| February | 646 | 0 | 546 | $56.32 | $139.46 |
| March | 677 | 0 | 486 | $55.23 | $136.07 |
| April | 795 | 0 | 476 | $60.69 | $148.71 |
| May | 817 | 459 | 1163 | $195.98 | $285.36 |
| June | 498 | 806 | 720 | $267.15 | $236.81 |
| July | 460 | 746 | 693 | $248.66 | $222.18 |
| August | 452 | 743 | 570 | $237.94 | $206.51 |
| September | 348 | 214 | 241 | $109.77 | $93.95 |
| October | 642 | 0 | 398 | $52.18 | $121.68 |
| Total | $1,437.53 | $1,969.11 |
Notes:
- The service fee premium for a ToU account over a regular account is $1.30/mo, or $15.60/yr, so the savings have to be adjusted by that amount
- January was an estimate since NV Energy has a difficult time with their billing system and time-of-use accounts – I signed up for e-bills but occasionally I’ll get a paper bill in the mail.
- The billing month crosses two months (I tend to get my meter read in the middle of the month)
- My Nest thermostats were set (manually) to cool the house down in the summertime to 70F by 12:30PM, a half hour before the peak period begins, and then were set to 76F the rest of the day. This was to cool the house down and then let it warm up when the electricity rates were higher
- This large cost savings may not last for much longer, NVEnergy has been consistently increasing the time-of-use rates in the last year, even my most recent bill had winter prices increase by about .4 cents per kWh. At this rate I would expect to be back to paying the same as the flat rate in 4-5 years.
Its my opinion that the Nest thermostats helped a lot in keeping the summertime energy use down, contributing to the savings. Beyond this, having cheaper overnight rates to plug in my Volt means that I pay about 2-3c/mile for my Volt for electricity (a Prius by comparison is about 7c/mile), which improves the ROI calculations on the Volt because I save more money compared to a gasoline car.