Charging an Electric Car

[jflorey2]

Any thoughts from someone who has both Solar and an EV would be greatly appreciated. I'm in a suburb of NYC if that makes a difference.

We have two EV's (a Prius Prime and a Tesla S) and a 10kW solar system. We still generate more than we use. The Prime gets 4 miles per kwhr and the Tesla gets 3 miles per kwhr. I drive about 4000 miles a year; my wife does about 8000 miles a year.

[organic farmer]

Just curious - which car do you have and what kind of range do you actually get?
Also, how long do you have it and how much lower has range gotten over time?

I have a 2017 Prius hybrid. So far we have not seen any decrease in EV range.

[solardreamer]

Just curious - which car do you have and what kind of range do you actually get?
Also, how long do you have it and how much lower has range gotten over time?

My hesitation about going to an electric car is range, and I'd be afraid to take it further than 20 miles from home for fear of running out of charge.
It's not like a gasoline car where you find the nearest gas station to fill up. I'd need to get into the habit of charging every night to make sure I have the full range available to me every day.
It would certainly take a lot of getting used to.

Also, I tend to keep my cars for a long time (20 years or longer) and I'm concerned about range when the car is 10+ years old.

I have have/had multiple: Mercedes B250, Chevy Spark EV, Tesla Model 3. I usually get between 3-4 miles/kWH. It's easy to get into the habit of plugging your car in when you park at home. Much less hassle than going to gas stations. And no oil changes or smog checks. 20 miles is no concern for recent models. Many have 200+ miles range now. Longevity remains to be seen.

[JayG]

Mainstream L2 home charging stations (charger is actually in the EV) can charge up to 9.6kW (40A@240V). Since you are overproducing, the financials most depend on your specific rate plans and when you charge. If you have a good time of use rate plan with net energy metering and you only charge during off-peak periods then you could very well charge to your EV for very low cost. I charge overnight with solar production covering most of my usage and I had calculated that I was paying about 1/5 to 1/4 the equivalent per mile energy cost for my EV compared to my previous gas car.

Just curious - which car do you have and what kind of range do you actually get?
Also, how long do you have it and how much lower has range gotten over time?

My hesitation about going to an electric car is range, and I'd be afraid to take it further than 20 miles from home for fear of running out of charge.
It's not like a gasoline car where you find the nearest gas station to fill up. I'd need to get into the habit of charging every night to make sure I have the full range available to me every day.
It would certainly take a lot of getting used to.

Also, I tend to keep my cars for a long time (20 years or longer) and I'm concerned about range when the car is 10+ years old.

[JayG]

Mainstream L2 home charging stations (charger is actually in the EV) can charge up to 9.6kW (40A@240V). Since you are overproducing, the financials most depend on your specific rate plans and when you charge. If you have a good time of use rate plan with net energy metering and you only charge during off-peak periods then you could very well charge to your EV for very low cost. I charge overnight with solar production covering most of my usage and I had calculated that I was paying about 1/5 to 1/4 the equivalent per mile energy cost for my EV compared to my previous gas car.

I haven't actually paid for electricity since early 2016. The way my plan works is that all the power I produce goes into an "Energy Bank" of kW that I then draw from as I use electricity. Since the Spring of 2016 (my system was installed in December 2015 when production was low), my bank balance has always exceeded usage, and I typically have anywhere from 800 kW to 2500 kW at the annual reconciliation, which I get paid for (at a very low rate per kW).

So as long my extra usage to charge an EV doesn't exceed my overage for the year, I can run an EV for almost free (really the amount of money I'd no longer get since I'd no longer sell any excess power back to the utility). I'll need to research specific cars as outlined in the previous replies. The replies were helpful so thanks, everyone.

[solardreamer]

Mainstream L2 home charging stations (charger is actually in the EV) can charge up to 9.6kW (40A@240V). Since you are overproducing, the financials most depend on your specific rate plans and when you charge. If you have a good time of use rate plan with net energy metering and you only charge during off-peak periods then you could very well charge to your EV for very low cost. I charge overnight with solar production covering most of my usage and I had calculated that I was paying about 1/5 to 1/4 the equivalent per mile energy cost for my EV compared to my previous gas car.

[SunEagle]

You can follow JPM's estimation but it really depends on the EV you decide to purchase. Some of the small ones charge up pretty fast. Others take more power. Each manufacturer should provide an idea of what it takes to charge X% of the EV battery based on your estimated usage.

[J.P.M.]

You have a 12 kW PV system, not a "12KwH (sic) PV system.

I don't have an EV yet, but the preliminary #'s are pretty straightforward for a back of the envelope estimate.

Depending on vehicle size, driving habits and the weather (A/C and heater use included), an EV might be expected to get about 3 miles per kWh of battery capacity +/- some, perhaps more for smaller vehicles and probably less in very hot/cold weather.

For a rough approx. of a vehicle's possible miles driven per kWh of battery capacity used, take the published estimated range of the vehicle and divide it by the vehicle's battery capacity in kWh (not kW BTW).

A level 2 charger in your garage might be expected to be, as a 1st approx. about 90 % efficient.

So, if a vehicle's estimated range is, say, 200 miles and it has a, say, 70 kWh battery, you might plan on driving 200/70 = 2.86 miles for each kWh of battery capacity used.

Assuming, as a very rough 1st approx. that a level 2 charger might be about 90 % efficient , driving 5,000 miles/yr. and using the above rough numbers will require (5,000/2.86)/0.9 ~ = 1,943 kWh/yr. of electric energy.

Your mileage will vary.

[JayG]

Hi.

I am starting to think about buying an electric car. So I'm wondering, how much power does a full Level 2 charge use?

I've had a 12KwH solar system installed since 2015 and I tend to produce about 15 mW per year.
Of that, I overproduce anywhere from 1 to 3 mW.

I don't drive much - maybe 3000 to 4000 miles per year on the car that a new electric would replace.
I suppose if I can drive for free (or close to free), I'd use the EV more so maybe I'd drive up to 5000 miles per year.

So I'm wondering if I'd be able to run an electric car for next to nothing, since my only benefit from the overproduction now is the $150 or less that the utility pays me every year to buy back the excess power.

Any thoughts from someone who has both Solar and an EV would be greatly appreciated. I'm in a suburb of NYC if that makes a difference.