Is there a way to calculate cost of charging at home versus gasoline?

[Rothgarr]

Hi there! I'm in the market for a plug-in hybrid. We don't have many charging stations in our area so I'd mostly be charging at home. I'm specifically looking at a Honda Clarity.

Is there a way to determine what it would cost to charge the Clarity at home vs if I had to fill a car with the equivalent amount of gas?

And do home chargers use more/less electricity depending on if you use a 120 vs 240 charger at home?

Thanks!

 

[marshall]

A 240 volt charger (EVSE) will be more efficient so it will use less electricity. But more important is the convenience factor. So if you don't have to upgrade your electrical panel then it make sense to use the 240 charger, especially if you using up most of battery range each day.

Clipper Creek estimates the Clarity to have an acceptance rate of 6.6 KW and can be charged as fast as 4 hours. So multiple 6.6 times 4 and you get 26.4 KWh. The national electricity rate is 10.54 cents per KWh. So multiply .1054 times 26.4 and you get $2.78 to charge the car. If you can get 40 miles of range on the battery, that's about 7 cents a mile. Note if your cost of electricity is lower than the national average you cost per can be significantly less. Where I live the cost for electricity is about 6 cents per KWh. So my cost would be about 4 cents a mile.

For a comparison, find an equivalent size car and go the government web site to find it's mpg. Take this number and divide into the price of a gallon of gas in your area to find the cost per mile. For example, a regular Honda Accord gets 33 mpg combined. So if gas costs $2.75 per gallon then the cost per mile is $2.75 divided by 33 or about 8 cents a mile.

https://www.fueleconomy.gov/

 

[Rothgarr]

Cool, thanks!

We are currently paying 7.98 cents per kWh.

We are also in the process of meeting with solar companies to cover 100% of our electric needs. One of my dilemmas is deciding if I want to wait and get the solar first before I get a plug-in hybrid.

 

[ekutter]

Boy, I sure hope the Clarity can go further than 40 miles while using 26.4 kWh. That's like .66 kWh / mile, double the EPA rated mileage of 31kWh / 100mi. At 8cents / kWh, it would only cost 2.5cents / mile using the EPA rating. In my Volvo XC60 PLHE, I am getting nearly 50% better efficiency than the EPA rating this time of year. I'm using a Kill-o-watt to measure the actual electricity usage from the wall and often get 26 miles / charge rather than the EPA estimate of 17.

Just looked it up - the Clarity only has a 17 kWh battery so no way is it using 26.4 kWh to charge it. With 240v, it should be approximately 90% efficient. So worst case would be about 19kWh to fully charge it from empty. Even with 120v, it should be around 85% efficient.

https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=39786&id=39190&id=39836&id=39782

 

[Mark Miller]

Right, using ekutter's figure of $0.025 / mile EV...

and the EPA est 42 MPG gasoline (for the Clarity PHEV), at $2.75/gal, $2.75/42 = $0.065 / mile gasoline. Gasoline 2.5x times as costly.

 

[bwilson4web]

It is fairly easy: https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=39782

• 31 kWh/100mi * $/kWh = $$/100mi
• 2.4 gal/100mi * $/gal = $$/100mi

The EPA web site allows showing up to four vehicles side-by-side.

As for solar roof vs plug-in hybrid car, the local electrical rate, $0.10/kWh has remained fairly constant. Renewables coming online to the grid, wind and solar, have helped keep the rates constant. Furthermore, small solar continues improving technically although it may soon suffer from trade war inflation as might the Honda Clarity plug-in.

GOOD LUCK!
Bob Wilson

 

[Mark W]

Cool, thanks!

We are currently paying 7.98 cents per kWh.

We are also in the process of meeting with solar companies to cover 100% of our electric needs. One of my dilemmas is deciding if I want to wait and get the solar first before I get a plug-in hybrid.

You didn't say what state you live in. Here in CT, they have a very positive solar program with many incentives, including low interest loans. In order to use the program, you are not allowed to build a system that generates more electricity than your house has used over the last six or twelve months. So, if that is the case in your state, you would want the car before you build your solar.

 

[Carro con enchufe]

My estimated average cost to fill up is about $1.30 a charge (don’t always start at empty, there are days that my range is 20 or 30 when I plug in). My kWh cost is under 10 cents. You may be surprised how many free public chargers there are though. I only charge at home about 15 days a month, so the impact on my bill is $20 or less. Last month I saved $120 vs the cost of gas @ $2.75/gallon.

 

[Martik]

My volt gets about 66 miles / 14.1kw charge which costs $1.50

Gas here in Vancouver, BC is $5.67/US Gal and I was getting 25mpg in the old Accord, so that's $15 in gas for 66 miles or 10x the cost of driving the Volt.

And that's not including the 2-3 qts of oil I had to put for every tankful

 

[glockgirl]

The website for comparison is
mpge.com All u have to know is the size of battery in kw and price u pay from your electric company for 1 kw of electricity

 

[interestedinEV]

The website for comparison is
mpge.com All u have to know is the size of battery in kw and price u pay from your electric company for 1 kw of electricity

There is another factor, time of day pricing. My utility has special price for EV's, but there are other plans available that may be better for a plug in. Let us say you can do all your charging at night and you have time based pricing, your costs are less than if you did it at night rather than times of peak demand. Your calculations need to be tailored to your particular pricing plan rather than generic rates, in case you want to be particular. You could also use weighted averages, 75% at lowest price and 25% at the peak price or any combination based on your estimated usage patterns.

 

[interestedinEV]

Cool, thanks!

We are also in the process of meeting with solar companies to cover 100% of our electric needs. One of my dilemmas is deciding if I want to wait and get the solar first before I get a plug-in hybrid.

Problem with the waiting game is "what are you waiting for?". Let us current costs $2.50 to charge (without solar) but your current gas guzzler costs you $4.00 for equivalent mileage. Does it matter if you get your solar in two months, you are still saving (unless there is another dependency) based on the opportunity cost.

On the other hand, let us say that your current costs for charging are $3.10 and the equivalent gas costs are $2.90. However there is a big promotion going and you can get the car possibly $1000 cheaper today than two months later. Or you expect it to be cheaper 2 months from now. In that case does that saving in operational costs matter. There also could be issues like the one quoted by

You didn't say what state you live in. Here in CT, they have a very positive solar program with many incentives, including low interest loans. In order to use the program, you are not allowed to build a system that generates more electricity than your house has used over the last six or twelve months. So, if that is the case in your state, you would want the car before you build your solar.

In other words, there are many hypothetical scenarios, and you have to decide which one closely resembles your situation. There cannot be one universal answer. The answer depends upon the factors that you have to deal with.