Note: This ended up being WAY more than I was thinking I’d write when I hit reply. But I had fun writing it up. So /shrug. Imma post it.
… EVs, which can be charged at home using solar.
… have some solar on the roof, charge an EV with it
From the phrasing of these I assume you mean using solar as a sole means of charging an EV, as opposed to using them to offset your grid tied usage. Which might not be what you meant, but in case someone else reads this (I’d hazard a guess you already know this stuff), and makes that same assumption, I felt like adding some clarification.
Depending on your needs, solar is not always practical for charging an EV. An average EV uses 0.35 kWh per mile (0.21 kWh per kilometer if I did my conversion correctly). Say you had a 30 mile/48km daily commute (I further averaged results I found for average American and European daily commute distances to get that number). You would need 10.5kWh (30 * .35) of power to recharge.
Using the low end of a daily kWh generation estimate I found for a 400w panel (1.6kwh a day) you’d need 7 panels. Lots of environmental factors in play for solar so definitely give or take on that one. Said panels are about 80"x40" (2 meters x 1 meter), so fairly substantial.
And solar isn’t good at delivering a predicable and controllable amount of electricity over a long period of time which your EV expects. So you’re going to need batteries attached to your solar system. Minimally enough to hold however much power your system accumulates before peak output, as well as to contain any power generated above what’s being delivered to your car during the peak. And this assumes you can plug your car in for an extended period of time right in the middle of the day. If you don’t have that luxury, say you’re at work in the middle of the day, then you’d want to store that entire day’s worth of power until you could use it.
Then there’s charging. The limit here is probably whatever bottleneck there is in your system. Either the max continuous discharge rate of your batteries or the max continuous output of your inverter. A 3.6kWh charger, which would require a 220-240V inverter rated above 3,600 watts seems ideal as that would be about 3 hours of charging to recover the 10.5kWh I came up with earlier. For 120V countries (or if you want to buy a 120v inverter/ev charger, I suppose) you also have the option of a 1.4kWh charger with a 120v inverter rated above 1,400 watts. It would take about 8 hours to recharge 10.5kWh. Or, if for some reason you wanted an even slower system. I have a Bolt and I know it can do 8 amp charging, which works out to about 960 watts, and about 11 hours charge time.
Of course, if your range needs are lower, the system can be scaled down. Unsurprisingly, the less electricity you need the more feasible it is, right?
Edit: And environmental factors can be a big impact. I have a small solar setup (~1kwh) and something as simple as it being overcast the whole day has a huge impact on how much it generates. Most EV’s have quite a bit range, so not like one cloudy day is going to be a big problem in this scenario I’ve laid out. But a cloudy week? Might start to be a problem.
Note: This ended up being WAY more than I was thinking I’d write when I hit reply. But I had fun writing it up. So /shrug. Imma post it.
From the phrasing of these I assume you mean using solar as a sole means of charging an EV, as opposed to using them to offset your grid tied usage. Which might not be what you meant, but in case someone else reads this (I’d hazard a guess you already know this stuff), and makes that same assumption, I felt like adding some clarification.
Depending on your needs, solar is not always practical for charging an EV. An average EV uses 0.35 kWh per mile (0.21 kWh per kilometer if I did my conversion correctly). Say you had a 30 mile/48km daily commute (I further averaged results I found for average American and European daily commute distances to get that number). You would need 10.5kWh (30 * .35) of power to recharge.
Using the low end of a daily kWh generation estimate I found for a 400w panel (1.6kwh a day) you’d need 7 panels. Lots of environmental factors in play for solar so definitely give or take on that one. Said panels are about 80"x40" (2 meters x 1 meter), so fairly substantial.
And solar isn’t good at delivering a predicable and controllable amount of electricity over a long period of time which your EV expects. So you’re going to need batteries attached to your solar system. Minimally enough to hold however much power your system accumulates before peak output, as well as to contain any power generated above what’s being delivered to your car during the peak. And this assumes you can plug your car in for an extended period of time right in the middle of the day. If you don’t have that luxury, say you’re at work in the middle of the day, then you’d want to store that entire day’s worth of power until you could use it.
Then there’s charging. The limit here is probably whatever bottleneck there is in your system. Either the max continuous discharge rate of your batteries or the max continuous output of your inverter. A 3.6kWh charger, which would require a 220-240V inverter rated above 3,600 watts seems ideal as that would be about 3 hours of charging to recover the 10.5kWh I came up with earlier. For 120V countries (or if you want to buy a 120v inverter/ev charger, I suppose) you also have the option of a 1.4kWh charger with a 120v inverter rated above 1,400 watts. It would take about 8 hours to recharge 10.5kWh. Or, if for some reason you wanted an even slower system. I have a Bolt and I know it can do 8 amp charging, which works out to about 960 watts, and about 11 hours charge time.
Of course, if your range needs are lower, the system can be scaled down. Unsurprisingly, the less electricity you need the more feasible it is, right?
Edit: And environmental factors can be a big impact. I have a small solar setup (~1kwh) and something as simple as it being overcast the whole day has a huge impact on how much it generates. Most EV’s have quite a bit range, so not like one cloudy day is going to be a big problem in this scenario I’ve laid out. But a cloudy week? Might start to be a problem.