Published 11/14/2021
Time of Use Rates & EV TOU Option 2
On the open market, the cost of electricity varies according to the demand for electricity throughout the day.
Sometimes electric utility companies will also charge different prices for electricity to customers depending on the time of day. This is called a time of use rate, or time of day plan.
In Utah, Rocky Mountain Power is presently offering an experimental time of use rate for electric vehicle drivers as a way to incentivize them to not charge up during periods of high electric demand. This has been going on for several years now but is set to expire at the end of 2021, unless they decide to extend the schedule.
Time of Use Option 2:
I heard about this plan several years ago but since I lived in Kaysville, (serviced by Kaysville Power), I was not eligible. While building our new home in Layton, I became a customer of Rocky Mountain Power.
In early 2020, I decided to try out the experimental, time of use rate schedule 2E. It came in two flavors.
EV TOU1 (7 cents off-peak and 22 cents on-peak)
EV TOU2 (3.4 cents off-peak and 34.4 cents on-peak)
I decided to go for broke and signed up for the more aggressive time of use option 2 plan.
Since my house was so well insulated with lots of thermal mass, (effectively a heat battery inside a Yeti cooler), the HVAC system can go on standby for 5 hours at a time and the temperature of the house will barely move. Also since our heat-pump water heater is smart, it can be programmed to not run during this time either. The same goes with the electric vehicles. They can be plugged in whenever it is convenient and simply not charge up during the on-peak periods.
I also asked my wife and kids to limit energy intensive activities (like laundry and using the oven) to off-peak periods as much as possible. More on this later.
In this way, I estimated that 90% of our energy consumption would be taking place during the super inexpensive off-peak electric rate. I was nervous but
hopeful that this would save us money on electricity.
It turned out to be an absolutely fabulous deal on electricity.
| Month. | Off-Peak | On Peak | Total (kWh) | On/Off | Energy Cost | Avg Rate | Notes |
|---|---|---|---|---|---|---|---|
| 19-Oct | - | - | 1260 | - | $123.98 | $0.098 | Space heaters |
| 19-Nov | - | - | 1426 | - | $141.56 | $0.099 | Space heaters |
| 19-Dec | - | - | 3069 | - | $315.65 | $0.103 | Air Handler Installed |
| 20-Jan | - | - | 3038 | - | $312.37 | $0.103 | No HVAC yet, Resistieve Heat Only |
| 20-Feb | - | - | 3560 | - | $367.68 | $0.103 | No HVAC yet, Resistieve Heat Only |
| 20-Mar | - | - | 1958 | - | $197.93 | $0.101 | Less driving due to COVID-19 |
| 20-Apr | 1688 | 67 | 1755 | 3.97% | $80.43 | $0.046 | EV TOU2 3.4¢ off-peak 34.4¢ on |
| 20-May | 804 | 52 | 856 | 6.47% | $45.21 | $0.053 | |
| 20-Jun | 807 | 57 | 864 | 7.06% | $47.03 | $0.054 | HVAC installed |
| 20-Jul | 984 | 63 | 1047 | 6.40% | $55.12 | $0.053 | AC working but not optimized |
| 20-Aug | 1370 | 62 | 1432 | 4.53% | $67.90 | $0.047 | New washer/dryer |
| 20-Sep | 1228 | 66 | 1294 | 5.37% | $64.44 | $0.050 | BlueSkys 100% renewable power now |
| 20-Oct | 941 | 79 | 1020 | 8.40% | $59.15 | $0.058 | |
| 20-Nov | 1402 | 103 | 1505 | 7.35% | $83.08 | $0.055 | First winter using Air Source Heatpump |
| 20-Dec | 1590 | 115 | 1705 | 7.23% | $93.60 | $0.055 | Installed 0.9kW PV array, zero export |
My Total Home and Vehicle Energy Consumption in 2019 through 2020
For 2020, the on-peak electric consumption was only 6.31% of my total energy consumption for an average electric rate of only 5.2 cents per kWh.
Our average energy bill for 2020 was $66.22 as opposed to $134.74 if I had stayed with the standard, schedule 1 electric rate.
In 2020 alone, TOU2 saved me $822. What a deal!!
In 2021, the TOU2 rates dropped a little bit. I was now paying 32.4 cents on-peak and only 3.2 cents off-peak.
Even though my total energy bill was very low, and only 6.31% of my energy usage was on-peak, since it costs 10x more money, it comprised 38.5% of the energy portion of the bill.
I looked at my actual energy consumption while on peak. I averaged only about 3-4 kWh of energy during this 5 hour period each weekday. That is not that much energy and a relatively inexpensive battery bank could probably cover most if not all of it. I could charge it up using off-peak electricity and use it while on-peak.