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My sister and brother in law live off-grid and are asking me a question I don't know how to answer. She asks, "What I meant about how much power does it (my Volt) use was not what it costs (since remember we are off-grid and don't pay a utility bill per se) but actually what the power draw is. We actually are not in the market now for a new car, since we are very happy with our Honda CRVs, but Bill had been thinking about getting an all-electric car maybe as our next car, and so he was researching what size solar power system it would take to power up an all-electric car. What he has learned is that it's not realistic at this time. They need so much power you'd have to invest in a large stand-alone system that's as big as what runs our whole house. So then he wondered about the hybrid cars, such as the Prius or Volt."

Can you answer their question?
 

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My sister and brother in law live off-grid and are asking me a question I don't know how to answer. She asks, "What I meant about how much power does it (my Volt) use was not what it costs (since remember we are off-grid and don't pay a utility bill per se) but actually what the power draw is. We actually are not in the market now for a new car, since we are very happy with our Honda CRVs, but Bill had been thinking about getting an all-electric car maybe as our next car, and so he was researching what size solar power system it would take to power up an all-electric car. What he has learned is that it's not realistic at this time. They need so much power you'd have to invest in a large stand-alone system that's as big as what runs our whole house. So then he wondered about the hybrid cars, such as the Prius or Volt."

Can you answer their question?
Seriously, I am still unsure what the actual question is...
 

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That's a good question but the answer is a bit tricky. The battery capacity depending on model year is somewhere between 16-18 kWh, but you lose some energy to resistance and heat and such, so you can probably tack on another 1-2kWh to the actual capacity of the battery. But what she wants to know is how much power does the car pull from the grid while charging.

Maybe she can glean what she needs from this:
1120V charge
120*8= .960KW, .96 * 8 = 7.68 KW-Hr 8 Hours at 8 amps
120×12=1.44KW, 1.44 x 6 = 8.6KW-hr 6 hours at 12 amps

240v charge
240*16=3.84KW, 3.84 x 3 = 11.52 KW-Hr 3 hours at 240.
 

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For a gen 1, it's somewhere around 12kw to fully charge. As far as charge rate, you have options based on the chargers. For the 120V charger, you can draw 8 amps (960 watts per hour) or 12 amps (1440 watts per hour). With a 240V, you'll be limited to the options of the charger to limit the current. My 240V charger has a number of settings internal of the unit that will let you set a maximum charge rate, which is limited on the high side by the 3.6kw per hour rate of the internal charger of the Volt.
 

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My sister and brother in law live off-grid and are asking me a question I don't know how to answer. She asks, "What I meant about how much power does it (my Volt) use was not what it costs (since remember we are off-grid and don't pay a utility bill per se) but actually what the power draw is. We actually are not in the market now for a new car, since we are very happy with our Honda CRVs, but Bill had been thinking about getting an all-electric car maybe as our next car, and so he was researching what size solar power system it would take to power up an all-electric car. What he has learned is that it's not realistic at this time. They need so much power you'd have to invest in a large stand-alone system that's as big as what runs our whole house. So then he wondered about the hybrid cars, such as the Prius or Volt."

Can you answer their question?
it takes roughly 11.9 KwH to Fully charge my Volt’s(Gen1) depleted battery.
http://www.mychevroletvolt.com/chevy-volt-energy-usage-charging-on-240v-vs-110v
 

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A very rudimentary rule of thumb is to simply use the capacity of the battery. This will be an overestimation but does included the inefficiencies of the charger, wiring, etc. So if the Volt has a 16 kWhr battery, then figure 16 kW's of electricity to fill it from empty. Basically, this would give them a worst case scenario with a built in buffer.

A pass-thru meter such as a kill-a-watt device will give you a much more accurate number. There are some folks here who've done that and will be along to post their figures. Some EVSE units also report usage numbers (draw) via wifi.
 

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Power is kW. Energy is kWh. The power draw is 3.3 kW. I suspect this is what they're interested in. The energy draw depends on how many miles you drive at roughly 3 miles per kWh.
 

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There is a missing part to your sisters question. How much do they normally drive each day. I own a Bolt EV and my grid connected house is not setup to replace the full 238 miles range each night. But I can replace easily the 50 miles I drive each day to work. So the solar system would need to be sized big enough to replace the battery charge they normally use each day. The Volt may the perfect choice because you can always fall back on the ICE to power the car if needed.
 

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My sister and brother in law live off-grid and are asking me a question I don't know how to answer. She asks, "What I meant about how much power does it (my Volt) use was not what it costs (since remember we are off-grid and don't pay a utility bill per se) but actually what the power draw is. We actually are not in the market now for a new car, since we are very happy with our Honda CRVs, but Bill had been thinking about getting an all-electric car maybe as our next car, and so he was researching what size solar power system it would take to power up an all-electric car. What he has learned is that it's not realistic at this time. They need so much power you'd have to invest in a large stand-alone system that's as big as what runs our whole house. So then he wondered about the hybrid cars, such as the Prius or Volt."

Can you answer their question?
To really understand what's needed, you have to crank in the normal use case - how many miles do they expect to drive on a typical day? Are their habits consistent, or do they very a lot?

Any modern EV runs between 32 and 38 kWh per 100 miles from the wall - including the Volt (some PHEVs run higher, but they are unusual cases.) Using the higher end and the traditional "12k miles per year," you get about 4500 kWh per year - just over 12 kWh per day on average. If they live somewhere near you in NC, it looks like they should have around 5 hours of equivalent insolation for an annual average - which would mean 2.4 kW of solar panels would just about cover the "average" user in any modern EV. This is all averages, though - without the grid backing them this assumption set might cause problems in the dead of winter. (A Volt could just run on gas at that point, of course.)

The power draw itself isn't really important - the cars can all be told to respect a limit you put in place by settings on the EVSE, all the way down to about 600W on 120V if necessary - and all the cars can take at least 3.3 kW from a 240V, many of them can take 6.6kW and some can take 10 kW or more if you have it handy.

Of course, you need to give the car enough power to recharge the miles you drive daily in the time you have - which is why it all comes back to the driving habits and expectations, for a Volt or any EV.

Depending on where they live, if you do have an unexpected trip somewhere distant, there may be DCFC options for the EV away from home to make up the difference (but I wouldn't want to count on them for a daily charge.) Tesla has a much more extensive network than the others at the moment, but other options are getting better as well.
 

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also ,
Most off grid people would have no problem with DIY car charger cables and with the correct pilot wire signal
the volt can use 120 volts AC at 6 amps.
 

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The car never charges to 16-18 KWh. It's more like 10-11 useable KWh and add a kw or 2 for efficiency/cooling,
etc. That's for a full charge from "zero"

Minimum draw for OEM EVSE is 8 amps. At 120vac that's 960 watts.
 

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If they are concerned about the "power draw", the answer is 8 amps (maybe 6?) at 120V, on up to 16 amps at 240V.

Each 120V amp will replace about 0.4 miles of EV driving per hour connected (120V x 1a / 1000 x .85 x 4). The other assumptions are that charging efficiency is 85% (90% for 240V) and that the Volt can go 4 miles on each kWh.

Using this formula:
an 8 amp, 120 V connection will replace 3.2 miles per hour,
12 amps @ 120 V will replace 4.8 miles per hour,
12 amps @ 240 V will replace 10.4 miles per hour,
16 amps @ 240V will replace 13.8 miles per hour

As others have said, your sister needs to know how many miles of EV driving they want each day, and then determine if they have sufficient daylight and surplus kWh during the times the car is at home to generate that much juice. Of course, the Volt runs on gasoline, too, so if the days are cloudy they can still drive the car, and it's pretty efficient there, too.
 

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Plus they can charge away from home, if they happen to have a charger at work or where they shop, etc. In a best-case scenario, that could make the car practical with zero demand on their home system.

Another consideration is that since the car can either store or generate a lot of power, it could potentially power their home, if needed, and thus increase the dependability of their home system. However, if they already have a reliable backup generator, this is not much of an additional benefit.
 

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Many good answers already, so I won't echo them. But one additional thing: some/most EV manuals state the car must be charged from normal grid power. It will probably work with a decent quality off-grid inverter setup, but if it doesn't, that's on you... you won't get any support from the manufacturer. I'd want to test it first, or find someone else who has tested your exact setup, to be sure it all works.
 

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For a gen 1, it's somewhere around 12kw to fully charge. As far as charge rate, you have options based on the chargers. For the 120V charger, you can draw 8 amps (960 watts per hour) or 12 amps (1440 watts per hour). With a 240V, you'll be limited to the options of the charger to limit the current. My 240V charger has a number of settings internal of the unit that will let you set a maximum charge rate, which is limited on the high side by the 3.6kw per hour rate of the internal charger of the Volt.
Just FYI, "watts per hour" is incorrect... it's the equivalent to saying "horsepower per hour". Power (watts) is instantaneous. Amount of charge is in kWh (energy).
 

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1-3.3kW (3.6kW) for 4-12h depending on model year and charge required.

Minimum sustained power required is 1kW (8A @120V).

For winter standby heating, it will pulse off an on as required, up to 1800W. (if on L1 it should max out at what the L1 setting is, e.g. [email protected])
Summer cooling similar story, but AC can use more power and will dip into HV capacity where available if temp is critical.
 

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1-3.3kW (3.6kW) for 4-12h depending on model year and charge required.

Minimum sustained power required is 1kW (8A @120V).

For winter standby heating, it will pulse off an on as required, up to 1800W. (if on L1 it should max out at what the L1 setting is, e.g. [email protected])
Summer cooling similar story, but AC can use more power and will dip into HV capacity where available if temp is critical.
I haven't tried it, but I'm pretty sure the car will respect the 6 amp limit that's the lowest J1772 Pilot signal, so if draw was really critical you should be able to get it down to ~720W or so on 120V.

Of course, then it takes a small forever to charge, and that's when it's not freezing out. You need more power overall that way, too, because the overhead involved in keeping the computers awake and the TMS cooling/heating the battery pack becomes a big chunk of the power draw.
 

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I have a 2017 and a solar system but not off grid. I have attempted to gage the impact of charging on the system and do not believe peak draw ever exceeded 4KW. It's fairly obvious that the amount of power used going to be slightly higher than the battery capacity you are filling (18.1KWh from zero to full plus a small factor for inefficiency). However, I am guessing your sister and BIL want to know what the momentary electric draw will be. 4KW should cover it. Draw goes down as the battery starts to get full. Charging begins hard and slows down as it progresses.
I can attest that charging an electric car, even a Volt, is a major hit on your solar electric generation. My system is 8.8KW in Pennsylvania and some days the car takes half (sometimes all) the electric generation. Depends on the weather, season, efficiencies and how much you drive the car every day.
 

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I tell people that it's like running a hair dryer for 13 hours to go from empty to full on my Gen 2.

I like your analogy. Probably something helpful that the off-grid people can relate to. An electric space heater would be another good one. The other issue is when the car gets used and when it gets charged. Implies battery storage could be key factor, maybe even more important than how many kilowatts worth of panel they have.
 
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