Time of Day rates and EV ownership

[archie_b]

Two years ago I switched to a time of day electric rate to take advantage of off peak charging with my EVSE. Was it worth it? Absolutely yes.

Normal rate per kwh here is $0.1147 per kwh. Time of day rates are $0.196 peak time and $0.055 off peak. Off peak is 8pm to 8am and all weekends and holidays (about 1/3 of the year). 98% of my charging is done at home with 99% during off peak. The 2% charging away from home is free using Charge Point stations (none of which are located in the city I live in). My lowest percentage of off peak usage for my home and EVSE was 64%, the highest was 84% and the average was 76%.

My lowest electric bill was $46 and the highest $97. This includes $10 per month participation using renewable energy sources. Remember this is recharging using the EVSE and powering my home.

Over the last year I've averaged 4.5 miles per kwh. During warm months this increases to greater than 5.0, with an occasional 5.5. During the cold months it drops to 3.5 or less (worse was 2.7 during sub zero weather). With gas currently $3.60 a gallon, 4.5 miles per kwh, and an off peak rate of $0.055 this works out to 300 mpge. If I was on standard electric rates this would drop to 141 mpge.

For me time of day rates have worked beyond my expectations. It did require some life style changes, like running the dishwasher and doing laundry during off peak, but overall even my wife is pleased with the results. The general rule is if you can use 60% or more off peak you will save money. The higher the percentage over 60%, the greater the savings.

 

[Mart]

It's good to hear you have the option and are using it beneficially.

That being said, please realize the MPGe is solely based on energy content, not price. It may be confusing to people to use it in a financial context, even though that's what most people are really wanting to know, "How much money do you save?". Unfortunately, people are used to MPG figures on the window, and by establishing MPGe the government has gotten itself into the same quagmire of measuring light bulbs and lamps in "incandescent watt equivalent" rather than using the more effective lumens and CRI. Edmunds argues for a move to Monthly Fuel Costs, but even this must be based on an "average" driver figure which varies as much as EPA MPG estimates.
http://www.edmunds.com/car-news/fuel-mileage-equivalency.html

It's hard to come up with a money per mile estimate with fluctuating fuel prices, differing rates, and currency value fluctuations occurring daily or hourly. This editorial and the comments might be worth a read.
http://insideevs.com/op-ed-time-new-metric/

 

[JoeS]

...It's hard to come up with a money per mile estimate with fluctuating fuel prices, differing rates, and currency value fluctuations occurring daily or hourly. This editorial and the comments might be worth a read. http://insideevs.com/op-ed-time-new-metric/

Glad to see the media finally addressing this, as I had long been an advocate of this concept. We had addressed this topic a couple of years ago, with the metric mpg$ (coined by FiddlerJohn). For the i-MiEV, here's the table using the EPA consumption rate of 3.33miles/kWh:
http://myimiev.com/forum/viewtopic.php?p=923#p923
Here's the table using my 'actual' rate of 4.25miles/kWh:
http://myimiev.com/forum/viewtopic.php?p=3710#p3710

archie_b, sorry, I forgot in which part of the country you're located. :?: Back on topic, I have an all-electric house and I've had Time-Of-Use (TOU) ever since it was introduced about 25-years ago by Pacific Gas & Electric (our energy-supplying monopoly, uh, utility). Timers on major consumers such as electric hot-water heater and swimming pool pumps to ensure they don't run between noon and 6pm (my grandfathered E-7 rate, no longer available). My present baseline per-kWh rates are Off-Peak Winter = $0.08765, Off-Peak Summer = $0.08404, Peak Winter = $0.11769, Peak Summer = $0.33219, with worst-case being applied when 300% over baseline of $0.55604/kWh. Ref: http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_E-7.pdf

RANT: After I installed my PV solar, the way it works is that my electricity bill is reduced by the amount I generate at the rate in effect at that time, and totaled (True-Up) each year. At the end of 12-months, if I owe them money, I write them a check; if they owe me money, they zero it out and pay me nothing unless I actually produced more kWh than I consumed over the course of that year. The scoundrels convinced the legislature to pass a law remunerating solar producers only if we generate more electricity than we consume over the course of the entire year, which I don't quite meet. This way, they reap the benefits of my high-cost energy generation (on a summer afternoon) without paying me any more for it. Net result: since my electricity consumption bill is zero anyway I no longer have any incentive to conserve and thus plug in my car whenever I need to charge it, regardless of the time of day. How's that for an unintended consequence of convoluted legislation? I've been keeping track of the $ they've owed me, and the utility has zeroed-out about $2500 so far. As an aside, I recently did an amortization analysis and whereas I had originally projected my 6.6kW PV solar to be amortized in 15 years, using the car to justify the solar and the solar to justify the car I've 'paid off' the system in seven years and am now driving and living on 'free' electricity. I fully expect the utility to compensate by jacking up their monthly meter charge (presently about $4.50/mo) - besides, the utility model is falling apart (in Germany, there was so much excess power being generated at some peak points last summer that utilities were actually paying to have the excess taken off their hands!). California's renewables generation is actually quite well balanced with solar during the day and wind at night, the REALLY BIG looming problem being the late-afternoon transition hours ... oops, sorry for drifting off-topic. /RANT

 

[Don]

[archie_b, sorry, I forgot in which part of the country you're located. :?:

I'm guessing it's somewhere COLD . . . . or at least, somewhere they don't use much air conditioning during the summer months . . . . and/or, electric heat during the winter months

Here, we run the air conditioning about 8 or 9 months of the year and we pay a flat 11 cents per KWH. I'd hate to think what our bill would be if we were paying almost 20 cents from 8 AM to 8 PM everyday

I'm glad it's working out to be a plus for Archie, but anyone thinking of doing this needs to do the math based on where they live and how much power they use . . . . especially during the daytime. We probably spend less than $20 per month recharging the car - It's hard to find any great savings on that amount. If we only charged at night and the power cost was halved, it would be a $10 savings, vs the nearly doubled cost we'd pay running the house air conditioning during the peak hours

Don

 

[BillSF]

The off-peak rate here is about $0.04/kwh, and I get about 4.5mi/kwh=less than a penny a mile. Also, since most of my usage is at night, my entire electric bill went down! That's a negative cost to drive my "i"
Bill in SF

 

[JoeS]

The off-peak rate here is about $0.04/kwh, and I get about 4.5mi/kwh=less than a penny a mile. Also, since most of my usage is at night, my entire electric bill went down! That's a negative cost to drive my "i"

Hi Bill,

My guess is that you have PG&E's E-9 Rate for Low Emissions Vehicles.
Ref: http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_E-9.pdf

This is wonderful for you, as the average electric rate in San Francisco is around 22¢/kWh
Ref: http://www.bls.gov/ro9/cpisanf_energy.htm

As more solar gets online this entire rate structure is going to be turned upside-down, with the Duck Curve showing the net demand on the California electric grid: http://www.greentechmedia.com/articles/read/Youve-Got-to-Charge-Your-EV-While-the-Ducks-Are-Quacking

The huge looming problem for the utilities will be the dramatic demand change on the Grid at around 5pm (see that curve).

 

[fjpod]

Con Edison in NYC offers NO incentives to EV users. They do offer a time of day plan...but there is an increase in your daytime rate, with a small decrease in the night rate...bottom line?...it would be more expensive for me (and most New Yorkers, I suspect) to go on the time of day plan, because I use much more electricity to run my house, fridge, A/C, etc, during the day then I do running the charger for my car at night.

I try to avoid daytime charging anyway, especially in the summer. I suspect in NYC we don't have nearly as much solar entering the grid in the middle of the day.

 

[archie_b]

Glad to see some discussion on time of use/time of day/EV electric rates. For some, especially those in warmer climates, these reduced rates may not work. Those that live in moderate or cold climates, I live in Wisconsin and have gas heat, the off peak rates not only lower my EV cost to operate but reduced my home electric cost as well.

In my case off peak rates account for about 70% of the hours in a year (12 hours at night, all day Sat and Sun, plus holidays). My electric bill this month is $58.38 (75% off peak) which includes about 800 miles of EV use/recharging. I agree with Don that off peak rates, while cutting my recharging costs in half, saves only about $10 a month. It also reduces my home energy costs around $15-25 a month. What did it cost for these recurring savings month after month: nothing.

For fjpod: Con Ed may not have EV rates, but it does have a Plug-In Electric Vehicle Pilot Program you may want to consider.
http://www.coned.com/electricvehicles/

Check out what your electric utility offers in TOU/TOD/EV rates. It may work for you and the savings are recurring for both your EV and your home.

 

[fjpod]

Glad to see some discussion on time of use/time of day/EV electric rates. For some, especially those in warmer climates, these reduced rates may not work. Those that live in moderate or cold climates, I live in Wisconsin and have gas heat, the off peak rates not only lower my EV cost to operate but reduced my home electric cost as well.

In my case off peak rates account for about 70% of the hours in a year (12 hours at night, all day Sat and Sun, plus holidays). My electric bill this month is $58.38 (75% off peak) which includes about 800 miles of EV use/recharging. I agree with Don that off peak rates, while cutting my recharging costs in half, saves only about $10 a month. It also reduces my home energy costs around $15-25 a month. What did it cost for these recurring savings month after month: nothing.

For fjpod: Con Ed may not have EV rates, but it does have a Plug-In Electric Vehicle Pilot Program you may want to consider.
http://www.coned.com/electricvehicles/

Check out what your electric utility offers in TOU/TOD/EV rates. It may work for you and the savings are recurring for both your EV and your home.

Yeah, thanks for the heads-up... I was aware of this program...