Forums

Cost of home charging in Massachusetts

Cost of home charging in Massachusetts

My electricity bill in Massachusetts is divided into two parts - elecricity supply charge and delivery services charge. Each costs about 10 cents per kWh, for a total cost of 20 cents per kWh.
At 325 Wh/mile, and assuming a 10% efficency loss I need 536 kWh to cover 1500 miles in my model 3, costing me $107.
My acura TSX gave me 26 miles per gallon, which translates to $133 to cover the same distance at current fuel prices.
This is less than $30 savings for me per month. This is much less than the savings I was expecting. Am I missing something?

I was curious to know if this is consistent/similar for other Tesla owners in Massachusetts.

TeslaTap.com | 01. Januar 2019

I can't say for MA's costs, but do they have a time of day charging option? Often the costs of charging between midnight and 6 am are far lower. In some places, as low as $0.02 kW/h. Here in California, I get it at about $0.10 kW/h.

Also 325 Wh/mile in a model 3 is unusually high. Numbers in the 250 Wh/mile as an average seem more likely (will vary between Winter and Summer). Also 10% efficiency loss seems high, but 5-8% would be more reasonable.

Have you included the costs of oil and filter changes in your Acura? There may be other charges that your EV doesn't have (registration discounts in your state for EVs?).

Tesla2018 | 01. Januar 2019

250 wh comes to 4 miles per kw
1500 miles divided by 4 is 375 kw
375kw x 20 cents is $75 plus 10 petcent loss is 82.50

Im lucky since is about 9 cents for me if I use under 1000 kw per month and 11 cents for anything over that. Im in FL and use about 400kw in the winter and about 1500 in the summer without counting what the car uses.

LunaPilot | 01. Januar 2019

Compliments to Cherian on the details. I am in WMass and have not applied myself to this yet. Thanks for getting me rolling on it. TeslaTap we shouldn't forget the savings on brake jobs, exhaust systems, and the other mechanical parts that invariable start to fail in about 3 years (infrequent but significant). Finally, we bought in at the outset knowing that the Northeast (Mass in particular) was least favorable in terms of energy costs.

jordanrichard | 01. Januar 2019

You are not comparing apples to apples in your fuel cost comparisons. Using your numbers for your Acura, you are saying that you pay $2.34 a gallon for gas. Is that regular or Premium. I am south of you in CT and Premium cost $3.34. I know that gas is cheaper in MA, but not that much cheaper. The reason I keep bringing up Premium is because a car with the performance of a Tesla would require premium gas. So you should be using Premium gas prices for your comparison.

reed_lewis | 02. Januar 2019

Where I live in Mass, we have a municipal light and power company. I pay about 10.5 cents per kWh total. So for me the cost difference is significantly better.

And I would love to know where in Mass you are getting gas for $2.30 a gallon.... Plus the price of gas changes constantly while your electric rates will be consistent.

Your 325 Wh/mile is your winter consumption rate. In the summer it will go down significantly (around 275 or so) so that helps also.

You also did not factor in the convenience of pulling into your garage and plugging in without having to stop at a gas station every few days.

And the car is so much more fun to drive compared to an ICE car.

p.c.mcavoy | 02. Januar 2019

@jordanrichard - I know Tesla used premium fuel cost in their initial MS savings calculation, but in this case the OP is comparing to the car they replaced. Not everyone buys a Tesla because they are looking for a high performance vehicle. His Acura could just as easily be effectively a Honda Accord or Civic largely with just different emblems on it.

Once can also argue that at the moment we are enjoying low gasoline costs, which may or may not last, but the reality is that this is what they are experiencing at the moment. It’s like telling someone in Iowa or Illinois at the moment that they should be using $3.50 per gallon based upon costs in major metro areas on the coasts versus the real world numbers I saw this past week as low as $1.90 traveling to visit family.

And for those of you that are able to benefit from preferential EV charging rates, Time of Use plans, or net metering for your solar setup. That’s great, but does not apply for many of us. My electric provider (Duke, one of the larger in the US), does not offer any of those and is more than willing to take any energy I might chose to produce via a solar installation with at best compensating me at wholesale rates, while they charge me back at full retail.

Bottom line, no matter how hard you try, I don’t think operating cost is the way to justify the purchase of a Tesla, whether a Model S, X, or 3. I know any fuel savings I’ve realized have been more than offset by increased purchase cost and other higher operating costs, such as insurance, tires, and higher registration fees (which in my state is based upon the initial cost of the vehicle).

Yodrak. | 02. Januar 2019

"Not everyone buys a Tesla because they are looking for a high performance vehicle."

I agree, because that's not why I bought a Tesla. The high performance is a bonus, at those rare times I take advantage of it, but I was looking primarily for a more luxurious, longer range, EV than my Leaf. I determine the operating cost savings in comparison to my wife's Honda Odyssey, which the Model S replaced.

kcheng | 02. Januar 2019

@cherian, "At 325 Wh/mile, and assuming a 10% efficency loss I need 536 kWh to cover 1500 miles in my model 3, costing me $107.
My acura TSX gave me 26 miles per gallon, which translates to $133 to cover the same distance at current fuel prices.
This is less than $30 savings for me per month. This is much less than the savings I was expecting. Am I missing something?"

Massachusetts electric rates are over 50% higher than the national average which is what Tesla is using to calculate advertised savings, and gas is at relative lows. While gas may be $2.30 a gallon for you now, you have to factor in how much it would be averaged over the next 5 or 6 years.

cherian_vinay | 03. Januar 2019

Thanks to everyone for a very informative discussion. As many of you pointed out, the "325 Wh/mile" is due to using the heater in the winter! Today, I turned off the climate control and noticed that this number went below the "rated line"; it was around 230 or so. So, I should see much better numbers once the weather warms up.

I didn't buy the Tesla for the fuel savings. Performance, styling, fun-to-drive, zero-emissions were the main factors.
Nevertheless, I wanted to understand how much I was spending on charging the vehicle and why it was not lining up with my expectations.

jordanrichard | 03. Januar 2019

p.c.mcavoy, whether one bought a Tesla for the performance aspect or not, doesn't change the fact that they got inherently a performance car. So, one should compare the fueling costs of a performance car. I agree that one shouldn't use Tesla's numbers because what gas and electricity costs are to one's local area are most likely different. I believe Tesla uses $.11 per kwh as a price point for electricity. Here in CT I pay $.20, but gas costs are lower per gallon than the CA gas cost cited on their site.

jerrykham | 03. Januar 2019

No, P.C. had it correct. Just like you use the numbers for your locale as far as the price of gas vs. the price of electricity you use the numbers that make sense for YOU when you compare. For me, I replaced a Toyota Camry with a Model S. It would be ridiculous for me to compare the price of supreme gas when figuring out if my bill was going to go up or down (it went down by quite a bit). You are figuring the numbers that apply to you not against some theory.

BTW for the PG&E serviced areas of California (12 cents summer / 13 cents winter per kWh for charging at night with EV-A rate plan) vs. gasoline (currently $3.50 by my house) you come up with the electricity being quite a bit cheaper. Even using pay Supercharging (26 cents per kWh in CA) was quite a bit cheaper than gas. My wife got rid of a Honda CRV and moved to a Model 3 recently so we compared what our recent 1,135 mile trip cost with pay Supercharging vs what gas would have been and it was not even close. Charging cost $66.28 in the Model 3 and gas would have been $156.71 (for her prior CRV). But CA is a high gas price state of course.

Davidb0229 | 03. Januar 2019

I am also in Eastern MA and use Eversource. My average energy cost is actually 23-24 cents/kWh, including the monthly $7 fee. My Model S has a lifetime average of about 325 Wh/mile, so my numbers are about what the OP quotes.
Eversource had a Time of Use Rate but discontinued it (with DPU approval) last January, supposedly for lack of interest. I had it for about a year and saved about 10% on my bill.
I make a point of not claiming that buying a Tesla will save money compared to gas. The exceptions would be that Model 3 will be more efficient than my Model S, and that anyone in a city or town with a municipal utility will likely pay less, sometimes much less, than with Eversource or National grid.

jordanrichard | 03. Januar 2019

It’s funny how people go to such lengths to do a cost analysis when comparing their Tesla operating costs, when they most likely didn’t do that when going from one ICE car to another.

kcheng | 03. Januar 2019

@jordan, it's a heck of alot easier to compare ICE costs, when the biggest variable is just MPG.

reed_lewis | 04. Januar 2019

When comparing ICEs between each other @kcheng is correct. A higher MPG will cost less than a lower MPG.

The issue that makes it difficult with an EV is that the rated MPGe values really mean nothing because the price of electricity varies everywhere. It rarely changes, but it can double in price when moving from one town to another (Hudson, MA to Marlboro, MA for example).

My time is worth significantly more than the savings I get from an EV (even though my town (Hudson, MA) has some of the lowest electric rates in the state. I do not have to stop at a gas station ever and that is wonderful.

jordanrichard | 04. Januar 2019

Ya, I paid no attention to the "MPGe" number listed on my window sticker. At least here is my way of looking at it. The reason one pays attention to MPG in an ICE comes down to money. How much is it going to cost to fuel the car and go travel "x" number of miles. So if a car gets say 25 mpg and gas cost you $2.50 per gallon, each mile cost you $.10 per mile.

For my MS, I look how much energy I used up via my trip screen, multiply that by what I pay for electricity, then divide by the number of miles to get a per mile cost. On average it costs me $.05 per mile, which means my real MPGe (equivalent) is 50 mpg using the above example of 25 mpg (avg mpg of cars on the road). However, my MS replaced a gas Mercedes that on avg got 20 mpg and required Premium gas. As of today here in CT that is $3.30 per gallon which would work out to $.16 per mile.

Yes, I know that my method does not take into account "vampire drain" and such, but this method is close enough and far more accurate than just pulling a number out of thin air.

As reed_lewis points out, you have to then factor in the stuff that doesn't have a set dollar figure to it.

jordanrichard | 04. Januar 2019

Just one other quick real world example.

My wife drives a MB SL 500, gets 18 mpg around town, using premium gas at the aforementioned $3.30 per gal. For her to go to work and back (15 miles), costs $2.70. In my Model S, the same trip cost my $.75

Yodrak. | 04. Januar 2019

"P.C. had it correct. Just like you use the numbers for your locale as far as the price of gas vs. the price of electricity you use the numbers that make sense for YOU when you compare."

I agree.

Yodrak. | 04. Januar 2019

"it's a heck of alot easier to compare ICE costs, when the biggest variable is just MPG."

The type of gas required can also be a significant variable for people who are concerned with operating cost as well as performance. With an EV one generally gets both lower operating cost and higher performance as compared to the ICEV one might chose for the comparison.

kcheng | 05. Januar 2019

@jordan, "So if a car gets say 25 mpg and gas cost you $2.50 per gallon, each mile cost you $.10 per mile.

For my MS, I look how much energy I used up via my trip screen, multiply that by what I pay for electricity, then divide by the number of miles to get a per mile cost. On average it costs me $.05 per mile"

You need to stop thinking in MPG. Look at what you wrote, you've already made the transition to cost/mile. 10 cents for your ICE vs 5 cents for your BEV. Why make additional calculations to get to MPG?

jordanrichard | 05. Januar 2019

Kcheng, I was only doing that to come up with a real world MPG equivalent versus the 89 MPGe listed on my car’s window sticker. I understand, somewhat, how they came up with the 89 MPGe but it isn’t real.

sabbia | 05. Januar 2019

Now, finally, a fact-based instructive thread by people who want to learn and who want to be educated. Thanks to all.

Yodrak. | 05. Januar 2019

"I look how much energy I used up via my trip screen, multiply that by what I pay for electricity, then divide by the number of miles to get a per mile cost."

The thing is, the amount of energy your car uses as shown by the trip screen is less than the amount of energy you're paying for to use the car.

TeslaTap.com | 06. Januar 2019

To throw a wrench into some of these calculations, I have solar, so my electricity per mile is zero. Solar panels paid for themselves in about 3 years so it is really free electricity from now on. You may ask, what about trips - well, I have free Supercharging.

So the cost of fueling the most fuel efficient ICE car with the absolutely lowest price per gallon in the USA is still infinitely more expensive than powering my Tesla! Ok, others may not be in my situation, but don't discount getting solar and saving a lot more, but it is an added complication in figuring the costs over time.

kcheng | 06. Januar 2019

@teslatap, can you tell us a bit about your solar panel system, size, etc., what your state offers for incentives, etc. TIA.

neezer | 21. Mai 2019

MA is apparently the 3rd highest state in the nation on avg for electrical rates, at "20 cents". In reality though, any of the millions of us who have National Grid, pay more than that. I recently switched to what I think is the lowest possible supplier rate, of 9.900 cents, but because the delivery charge by NatGrid is ~11.6 cents, my total cost is 21.5 per KWh.

It's ironic, that MA is #1 in energy efficiency, year after year, yet they can't get their rates competitive with the rest of the country. Sad. And probably intertwined with some corruption to line the pockets of dweebs in suits and jackets...