Hypothetical question - solar charging

[audi321]

Hi all, so I was having a chat with a guy in the office and we were debating whether you could charge a car from solar.

Not sure if it's been discussed on here before, but we talked about 2 options.

Firstly, charging directly from solar panels. We thought this wouldn't work as you would need so many panels to generate the power needed.

Secondly, charging from something like this? i.e. an inverted 12v power pack (which in turn is charged by solar panels). Would this work?

Hypothetical question really as I have absolutely no intention of trying it lol.

[essayer]

Charging an EV? Plenty do. If you can get 1400W from the panel then a Zappi charger will send it to the car, and if it’s less it will use the house supply for the rest

[ARHarh]

You can charge a battery from any electrical supply what ever it is. The difficult bit is controlling that electricity so the battery does not explode or feeding enough electricity that it doesn't take 2 weeks to charge. So any of those will work as long as you can control when to stop and start the charge.

Obviously if you were trying to replace 60kwh of consumption you would need 60kw of solar panels so you would probably need about 200 panels which would considerably increase you electric consumption dragging them around.

[No ideas for a name]

audi321 said:

Hi all, so I was having a chat with a guy in the office and we were debating whether you could charge a car from solar.

Not sure if it's been discussed on here before, but we talked about 2 options.

Firstly, charging directly from solar panels. We thought this wouldn't work as you would need so many panels to generate the power needed.

Secondly, charging from something like this? i.e. an inverted 12v power pack (which in turn is charged by solar panels). Would this work?

Hypothetical question really as I have absolutely no intention of trying it lol.

Depends what you mean.
A few panels are not going to 'directly charge your EV. An array, with an inverter can be set up to do so.

The example portable inverter won't do it. It has a 200W solar array, wich even with zero losses would mean you need 450 hours of direct sunlight to charge a 90kWh battery.

The amount of energy stored in a vehicle battery shouldn't be under estimated.

[No ideas for a name]

ARHarh said:

You can charge a battery from any electrical supply what ever it is. The difficult bit is controlling that electricity so the battery does not explode or feeding enough electricity that it doesn't take 2 weeks to charge. So any of those will work as long as you can control when to stop and start the charge.

Obviously if you were trying to replace 60kwh of consumption you would need 60kw of solar panels so you would probably need about 200 panels which would considerably increase you electric consumption dragging them around.

The vehicle contains the charger, so takes as much as it is 'allowed' by the EVSE.
You would only need 60kW solar panels if you wanted to complete the charge in 1 hour (when the sun was shining).

Of course in a simple system, without storage, your vehicle has to be sitting there doing nothing when the sun is shining.

[Dave Hedgehog]

lots of people charge EVs via solar, you can also dump the power to a battery to use in your house or charge your car

lots of viable solutions available such as

https://www.youtube.com/watch?v=gP51JjnWvLo

https://www.youtube.com/watch?v=8VdF_mbpGK8

[rugbyleague]

I charge my car with solar when the big lad is shining and the car is available for receiving electricity.

Getting both at the same time isn't the easiest but I do manage some free miles during the summer (free apart from the investment in the panels).

[sideways sid]

Or cut out the grid and charge the batteries from solar panels in the bodywork:

https://www.aptera.us/

Probably more suited to California than Cheshire though.

Edited by sideways sid on Thursday 2nd December 14:10

[audi321]

sideways sid said:

Or cut out the grid and charge the batteries from solar panels in the bodywork:

https://www.aptera.us/

Probably more suited to California than Cheshire though.

Edited by sideways sid on Thursday 2nd December 14:10

lol I like the idea.........so come on, who's clever enough to work out how many 200w solar chargers it would take to charge a 75kw car? Surely it's not as simple as 75000 / 200? i.e. 375 panels? These solar panels are 12v aren't they so I assume some kind of inverter is needed? What does that do to the watts figure?

Edited by audi321 on Thursday 2nd December 14:21

[Fastdruid]

audi321 said:

sideways sid said:

Or cut out the grid and charge the batteries from solar panels in the bodywork:

https://www.aptera.us/

Probably more suited to California than Cheshire though.

lol I like the idea.........so come on, who's clever enough to work out how many 200w solar chargers it would take to charge a 75kw car? Surely it's not as simple as 75000 / 200? i.e. 375 hours? These solar panels are 12v aren't they so I assume some kind of inverter is needed? What does that do to the watts figure?

Yep, it is that simple. The car is 75kWh which means it'll do 75kW for an hour or less W for more hours.

So 200W Solar for an hour will give 0.2kWh which means to fully charge a 75kWh battery it will take 375 hours. Or 375 200W panels will take an hour.

[annodomini2]

audi321 said:

sideways sid said:

Or cut out the grid and charge the batteries from solar panels in the bodywork:

https://www.aptera.us/

Probably more suited to California than Cheshire though.

Edited by sideways sid on Thursday 2nd December 14:10

lol I like the idea.........so come on, who's clever enough to work out how many 200w solar chargers it would take to charge a 75kw car? Surely it's not as simple as 75000 / 200? i.e. 375 panels? These solar panels are 12v aren't they so I assume some kind of inverter is needed? What does that do to the watts figure?

Edited by audi321 on Thursday 2nd December 14:21

75000 / 200 / ~0.9 for efficiency.

DC-DC converter or you can get high voltage panels.

[audi321]

Fastdruid said:

audi321 said:

sideways sid said:

Or cut out the grid and charge the batteries from solar panels in the bodywork:

https://www.aptera.us/

Probably more suited to California than Cheshire though.

lol I like the idea.........so come on, who's clever enough to work out how many 200w solar chargers it would take to charge a 75kw car? Surely it's not as simple as 75000 / 200? i.e. 375 hours? These solar panels are 12v aren't they so I assume some kind of inverter is needed? What does that do to the watts figure?

Yep, it is that simple. The car is 75kWh which means it'll do 75kW for an hour or less W for more hours.

So 200W Solar for an hour will give 0.2kWh which means to fully charge a 75kWh battery it will take 375 hours. Or 375 200W panels will take an hour.

So what about the voltage? A 12v to 240v inverter doesn't affect things?

[Fastdruid]

audi321 said:

Fastdruid said:

audi321 said:

sideways sid said:

Or cut out the grid and charge the batteries from solar panels in the bodywork:

https://www.aptera.us/

Probably more suited to California than Cheshire though.

lol I like the idea.........so come on, who's clever enough to work out how many 200w solar chargers it would take to charge a 75kw car? Surely it's not as simple as 75000 / 200? i.e. 375 hours? These solar panels are 12v aren't they so I assume some kind of inverter is needed? What does that do to the watts figure?

Yep, it is that simple. The car is 75kWh which means it'll do 75kW for an hour or less W for more hours.

So 200W Solar for an hour will give 0.2kWh which means to fully charge a 75kWh battery it will take 375 hours. Or 375 200W panels will take an hour.

So what about the voltage? A 12v to 240v inverter doesn't affect things?

Simple answer, no.

The power remains the same even while the voltage changes.

Watts is power and that is voltage multiplied by amps. So 200W at 12V is 16A, 200W at 240V is only 0.83A.

Of course the longer answer is "yes" because there will be losses in conversion.

[audi321]

Fastdruid said:

Simple answer, no.

The power remains the same even while the voltage changes.

Watts is power and that is voltage multiplied by amps. So 200W at 12V is 16A, 200W at 240V is only 0.83A.

Of course the longer answer is "yes" because there will be losses in conversion.

Wow, so working it backwards, if I bought 10 x 200w chargers (and a suitable inverter) I could get roughly 7 miles of range per hour charge? That's not too bad - similar to a 3 pin plug charger speed

[Fastdruid]

audi321 said:

Fastdruid said:

Simple answer, no.

The power remains the same even while the voltage changes.

Watts is power and that is voltage multiplied by amps. So 200W at 12V is 16A, 200W at 240V is only 0.83A.

Of course the longer answer is "yes" because there will be losses in conversion.

Wow, so working it backwards, if I bought 10 x 200w chargers (and a suitable inverter) I could get roughly 7 miles of range per hour charge? That's not too bad - similar to a 3 pin plug charger speed

In theory yes. In reality...no. Because that 200W is the maximum not how much it *actually* produces. You then have to take the sun into account, ie how strong and how much you get.

At a more realistic figure you're probably nearer 0.8kWh per 200W panel and with an inverter that's going to be nearer 0.72kWh

On the assumption that you need ~0.3kWh per mile range you're actually only going to get 2.5Mile range per *day* out of each panel. So 10 panels would give you 25 Miles range in a day...and cover 14m^2.

[anonymous-user]

For most of the world, putting solar panels on the actual car is absolutely idiotic


1) it's utterly un-necessary, as a typical passenger car is parked for 98% of it's life

2) It's hugely costly, meaning the £ per kWh is so high as to be none viable (or the for the same cost you could charge many more cars using cheap building roof mounted panels)

3) Cars get dented and crashed, solar panels on the bodywork is going to push insurance costs even higher than they currently are


So whilst the typical insolation at ground level can approach 1.2kW/m^2, a car is

1) not a great shape to fit solar panels
2) realistically, only two sides are going to be pointing at the sun at best
3) Cars get dirty, dirty solar panels have poor efficiency
4) You can't park in the shade of trees or buildings, well anything in fact.

But the biggest issue is the cost, requiring the panels to be engineered into the body work (not cheap) safely wired up (not cheap, esp wrt to HVDC safety), and the power conversion between the panels and battery (which requires a MPPT dcdc converter) must now be born by the manufacturer of the vehicle

A few cars have used panels to trickle charge the LV (12v) battery, helping to maintian that small batteries SoC when parked up for long periods, and a few of the silly start ups like Sono, are claiming to be going to production with integrated panels, but will almost certainly go bust, given how much their (rubbish) product is going to end up costing)

[audi321]

Max_Torque said:

For most of the world, putting solar panels on the actual car is absolutely idiotic


1) it's utterly un-necessary, as a typical passenger car is parked for 98% of it's life

2) It's hugely costly, meaning the £ per kWh is so high as to be none viable (or the for the same cost you could charge many more cars using cheap building roof mounted panels)

3) Cars get dented and crashed, solar panels on the bodywork is going to push insurance costs even higher than they currently are


So whilst the typical insolation at ground level can approach 1.2kW/m^2, a car is

1) not a great shape to fit solar panels
2) realistically, only two sides are going to be pointing at the sun at best
3) Cars get dirty, dirty solar panels have poor efficiency
4) You can't park in the shade of trees or buildings, well anything in fact.

But the biggest issue is the cost, requiring the panels to be engineered into the body work (not cheap) safely wired up (not cheap, esp wrt to HVDC safety), and the power conversion between the panels and battery (which requires a MPPT dcdc converter) must now be born by the manufacturer of the vehicle

A few cars have used panels to trickle charge the LV (12v) battery, helping to maintian that small batteries SoC when parked up for long periods, and a few of the silly start ups like Sono, are claiming to be going to production with integrated panels, but will almost certainly go bust, given how much their (rubbish) product is going to end up costing)

=PARTY POOPER

[anonymous-user]

For reference, this is small, ugly, crappy, city car from a manufacturer with no network or previous history, and it costs the same or more than a VW ID.3 or Pug 208e, or MG ZS

https://sonomotors.com/en/preorder/


£28,000 anyone? Anyone at all??? ;-)

[anonymous-user]

audi321 said:

=PARTY POOPER

Quite possiibly, but the truth hurts eh! :-)

[blank]

Realistically the best way to "charge with solar" is to export the electricity to the grid when the output is highest and your car is parked at work, then use cheaper electricity overnight to charge the car while it's on the drive.