Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register
  • The final cut of the 8th episode of the Tesla Motors Club Podcast, featuring Balazs Biro, of the prominent Hungarian EV channel Villanyautósok, is now available. You can watch it now on YouTube or listen to it on all major podcast networks.

Duke Energy - Time of Use

My 90D will hopefully arrive in the next month or so. In preparation, I have been trying to run the numbers on changing from the Duke Energy Residential Service to the Time of Use service. Has anyone else looked into this? It seems pretty straightforward, but I want to make sure there are no "gotchas" that I am missing
 

Cyclone

Cyclonic Member ((.oO))
Jan 12, 2015
5,058
1,153
Charlotte, NC
Duke Energy's Time of Use schedule for North Carolina (RT) isn't worthwhile unless you have a solar array due to the peak demand charges. With my numbers, it would be a bill increase compared to now. I am unsure of SC. I suggest this thread gets moved to the Southeast Forum or Charging standards forum.
 

David_Cary

Active Member
Dec 17, 2012
1,305
920
Cary, NC
Wait - Cyclone. TOU is not TOU-D. The D being demand charges. I have solar and Duke paid me a lot of money to go on TOU-D for 5 years. I save almost as much from the TOU-D rate schedule as I do from the solar panels.

TOU-D last I heard was only available to solar customers.

TOU likely makes sense with EV owners. Remember in the calcs that all weekend is off peak. TOU is meant to be revenue neutral for the average customer. An EV puts you into the Non-average category. In the summer, you freeze the house at night a little more - and you become more Non-average. Run dishwasher at 9 pm. Timer on hot water if electric. It isn't hard. There isn't a shoulder time with TOU-D but I hit 75% off peak and 25% on. I allow the 25% because it is completely solar offset. I could probably get down to 15% (summer).

Cyclone - look into TOU. As an aside, people look at demand as worst case. I typically hit 5 kw but I hit 15-20 at night and that is with only 20A EV charging. Solar tempers the peak demand very little - there is always a cloudy 90 degree day - and always a 30 min thunderstorm once a month even if the day was sunny. I have electric hot water, electric ovens, electric dryer, 5000 sqft a/c ed (7 tons) and 2 EVs - and I run heat pump in the winter.

My bill averages $1200 a year. Without solar $1800. Without TOU-D $2600. I assume that TOU will get me to $1000 when my 5 years on TOU-D are up.

Just looked at Duke "assumptions" - they assume 75% off peak which is a little aggressive for "average customer".
 
Last edited:
I'm on it and have been for just over a year and don't have solar. Saving about $40 a month averaged out over the year I'd estimate, though I'll need to run the numbers for specifics. Very much worth it for me though you have to be carful to not have too much concurrent demand.
 
Last edited:

Cyclone

Cyclonic Member ((.oO))
Jan 12, 2015
5,058
1,153
Charlotte, NC
I'm on it and have been for over a year and don't have solar. Saving about $40 a month averaged out over the year I'd estimate, though I'll need to run the numbers for specifics. Very much worth it for me though you have to be carful to not have too much concurrent demand.

All will vary depending on use. Saving $40/mo would mean my bill is cut nearly in half. I'll check it out, but last time, I was pointed to RT which has demand charges.

This is the schedule I am on:
http://www.duke-energy.com/pdfs/NCScheduleRE.pdf

And these are the Time of Use I see available (and they have demand charges, though the first one is peak-only):
http://www.duke-energy.com/pdfs/NCScheduleRT.pdf
http://www.duke-energy.com/pdfs/NCScheduleRST.pdf
http://www.duke-energy.com/pdfs/NCScheduleRET.pdf
 
All will vary depending on use. Saving $40/mo would mean my bill is cut nearly in half. I'll check it out, but last time, I was pointed to RT which has demand charges.

This is the schedule I am on:
http://www.duke-energy.com/pdfs/NCScheduleRE.pdf

And these are the Time of Use I see available (and they have demand charges, though the first one is peak-only):
http://www.duke-energy.com/pdfs/NCScheduleRT.pdf
http://www.duke-energy.com/pdfs/NCScheduleRST.pdf
http://www.duke-energy.com/pdfs/NCScheduleRET.pdf

I am on the first one, RT, and it works for me with the combination of the Tesla and the fact that I have some equipment in my house that runs 24/7. Not a huge draw, but always on. Some months are better than others and there is a loss of convenience with having to work around the peak times for drying cloths and using the stove. For most people it wouldn't make sense, but for me it does.

Here is I think my biggest bill this summer compared to the same month last summer, using their comparison tool. The amount of power used is roughly the same:

2015-11-05_10-25-59.jpg

2015-11-05_10-26-48.jpg

2015-11-05_10-26-31.jpg


EDIT:

Going back and scrolling through the bills, I over-estimated, its more like an average of $30 a month savings.

EDIT2: also note that Duke Energy and Duke Energy(Progress) are still separate and offer different things. At the time I signed up, I requested to get this TOU plan:

Time-of-Use R-TOU Program- - Residential-Duke Energy (WARNING: Auto-Play video, turn down the volume)

But that is for Progress customers only apparently, not Duke Energy customers. They could do a little better on the clarification there.
 
Last edited:

Cyclone

Cyclonic Member ((.oO))
Jan 12, 2015
5,058
1,153
Charlotte, NC
Yeah, I only use 40-45(-ish) kWh/day. With your $0.0991/kWh vs. my $0.1056/kWh, we are talking $0.25(-ish) per day difference, then you add in any demand charges. It doesn't work for my use profile, but it could for others.

But that was my point, each person should run their numbers b/c the demand charges may make this not work out for you if your numbers don't fit right.
 
Last edited:
I'm on RT - Residential Service TOU in Durham (not a Progress area) without solar panels. I don't charge during peak demand metering hours. My electricity usage is pretty crazy, even without the Model S, but I just checked and last month's bill was $350 and it would have been $420 on the old flat-rate plan so I guess I was smart to make the change.

Net savings aside, I take comfort in the fact that the marginal cost to charge my Model S is less than $0.06/KWh.
 
I am in Charlotte on TOU. I use way more power now, and my bills are similar to what they were before. We avoid charging and doing wash, dishwasher, etc in peak hours.

Duke Energy's Time of Use schedule for North Carolina (RT) isn't worthwhile unless you have a solar array due to the peak demand charges. With my numbers, it would be a bill increase compared to now. I am unsure of SC. I suggest this thread gets moved to the Southeast Forum or Charging standards forum.
 

ewoodrick

Well-Known Member
Apr 13, 2018
5,285
4,289
Buford, GA
Indeed, one of the concepts of a TOU rate, not necessarily driven by the Power Company, more from the Public Utilities Commission is that the should be revenue neutral. But their definition is more along the lines of "averaged out over thousands of users" So that means that some win and some lose. And in many cases, a standard rate is more like an insurance policy than a TOU is like raw cost.

First, many rates have seasonal changes, so make sure to look at summer vs winter usage.
When using a TOU rate, one of the basic concepts is can you move load from one time to another. If you are going to leave everything as it is, then you don't tend to take advantage of a TOU rate. So, when charging a car, that means that you will want to delay starting charge until the lower tiers go into effect. That's not that big of an issue, since the car supports it, but what happens if it takes longer to charge than the low rate period.

To really figure out what your cost is going to be, you need to look at what your usage is during the different hours, so that means you need something that can measure it. Knowing what your overall bill is, doesn't mean much.

But look at what your charging requirements are. If you are using 250 wh per mile, then that's going to be 1 kWhr for every 4 miles. Looking at https://www.duke-energy.com/_/media/pdfs/for-your-home/rates/electric-nc/ncschedulers.pdf?la=en says that it will be about 8.7 cents per kWhr
If you look at charging 10,000 miles all at home, that's about $217 per year. Is it worth it to change for $18 per month? Just look at the gas bill that you decreased.

And caveat before people jump on. This is NOT California rates, this is Carolina rates, huge difference.
 
Just did a comparison wtih my bills pre and post tesla/tou for Duke in Charlotte, NC.

Using my Aug 2017 bill vs my Aug 2016 bill (no tesla)

Pre TOU/No Tesla I averaged 10.3cents KWH
Post TOU/Tesla I averaged 8 cents KWH

With a total usage of 2300KW for the month, I saved roughly $53 over the standard rate. Some months I save a little, but I have never paid more from switching to TOU.
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top