Charging 12V Battery using solar

[Socalsp3]

Just wondering if a solar panel like this on the roof of your car can be used to top off the 12V battery. This theoretically can improve range since less power from HVB will be used to charge the LVB during driving, maybe also improve range if LVB is used a lot. I'm not sure if the heater/ac uses LVB or just electronics. Maybe this also can keep the LVB topped off preventing LVB problems If you park in the sun. Probably would need a bigger panel on your roof to make a difference but sounds like a cool project.

https://www.amazon.com/SUNER-POWER-...TKMZ4/ref=dp_prsubs_2?pd_rd_i=B07Y5TKMZ4&th=1

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[bshaw]

I do not think you could increase range by any noticeable amount by “saving” having to charge the 12V. The difference in battery sizes between LVB and HVB is enormous.

But, yes I suppose a solar panel could keep the LVB topped off if you’re parking outside and not driving for an extended period, which I think is what that product is designed for.

 

[Socalsp3]

I do not think you could increase range by any noticeable amount by “saving” having to charge the 12V. The difference in battery sizes between LVB and HVB is enormous.

But, yes I suppose a solar panel could keep the LVB topped off if you’re parking outside and not driving for an extended period, which I think is what that product is designed for.

LVB is small but it's constantly recharged by hvb so it can take some power away from hvb over a long trip. what percent of power is not going to the drive train would you say during an average trip? i wouldnt put a panel on a car for drag reasons just curious.

 

[HuntingPudel]

It might get you a few extra yards over the course of a long trip if you can keep your speed low enough so that the aerodynamic offset isn’t an issue. ?‍?

 

[MachEZRt1]

Home solar would reduce the cost of both charging your HVB and LVB . Have had ours for a year and love it.

 

[chrisGT]

Fisker will have a solar panel roof. They claim this will provide 1500 miles per year at a sunny location like California, assuming you park outside during the day.
https://www.motortrend.com/news/2023-fisker-ocean-solar-roof-charging-details/

Hyundai Ionic will also have an optional solar roof. I guess in a few years most manufactures will offer solar roof options.

 

[bshaw]

Fisker will have a solar panel roof. They claim this will provide 1500 miles per year at a sunny location like California, assuming you park outside during the day.
https://www.motortrend.com/news/2023-fisker-ocean-solar-roof-charging-details/

Hyundai Ionic will also have an optional solar roof. I guess in a few years most manufactures will offer solar roof options.

There is just isn't enough surface area on a typical vehicle to recoup any meaningful amount of range from solar panels. This is a physics limitation, not something that can be "innovated" into existence. If you want to power a mass market EV entirely from solar, you need something the size of a house roof to get enough energy to make it viable.

Unless you are willing to massively cut weight and make other huge tradeoffs, vehicle mounted solar panels are not going to be worth it -- ever. Aptera is targeting this opportunity, and their vehicle looks promising, but it's not practical for people who are expecting a seamless transition from what an ICE vehicle has provided historically.

 

[dtbaker61]

Just wondering if a solar panel like this on the roof of your car can be used to top off the 12V battery. This theoretically can improve range since less power from HVB will be used to charge the LVB during driving, maybe also improve range if LVB is used a lot. I'm not sure if the heater/ac uses LVB or just electronics. Maybe this also can keep the LVB topped off preventing LVB problems If you park in the sun. Probably would need a bigger panel on your roof to make a difference but sounds like a cool project.

https://www.amazon.com/SUNER-POWER-...TKMZ4/ref=dp_prsubs_2?pd_rd_i=B07Y5TKMZ4&th=1

1. you do not need to 'top up the 12v battery'
2. ruining the aero on your roof with a rigid panel would cost you more range than energy you'd gain
3. flexible flat solar panels don't last more than a year or two.

 

[SpaceEVDriver]

1. you do not need to 'top up the 12v battery'
2. ruining the aero on your roof with a rigid panel would cost you more range than energy you'd gain
3. flexible flat solar panels don't last more than a year or two.

Agreed on all counts.
In fact, #3 is worse. All PV panels generate heat as part of the inefficiencies. A flat panel attached to anything that isn't designed to transfer that heat is asking to fail. How do I know?

Because I had flat panels on my travel trailer and they melted the rubberized roof material in several spots where the excess heat had nowhere to go. I had imagined that it wasn't nearly as big a deal as some warnings had suggested. I was wrong and learned the hard (but not too hard--no fires) way.


Don't bother with a small panel. You can't generate enough energy to make a difference in the range, and it will be a hassle.

Consider: A large panel that you can move around yourself can do 100 Watts maximum, best-case. More likely about 33 Watts. Your car uses about 330 Wh/mile. If you were charging your HVB with this panel (no consumer panels generate the voltage required, but we're playing pretend here), it would take about 10 hours of sunlight to generate a 1 mile range improvement. Trickle charging the LVB will not help you with range.

 

[dtbaker61]

There is just isn't enough surface area on a typical vehicle to recoup any meaningful amount of range from solar panels. This is a physics limitation, not something that can be "innovated" into existence. If you want to power a mass market EV entirely from solar, you need something the size of a house roof to get enough energy to make it viable.

Unless you are willing to massively cut weight and make other huge tradeoffs, vehicle mounted solar panels are not going to be worth it -- ever. Aptera is targeting this opportunity, and their vehicle looks promising, but it's not practical for people who are expecting a seamless transition from what an ICE vehicle has provided historically.

exactly.

a roof mounted, or interior mounted PV panel might produce enough watts to run a small dc ventilation fan to dump hot air out the window, but that's about it.

 

[SpaceEVDriver]

There is just isn't enough surface area on a typical vehicle to recoup any meaningful amount of range from solar panels. This is a physics limitation, not something that can be "innovated" into existence. If you want to power a mass market EV entirely from solar, you need something the size of a house roof to get enough energy to make it viable.

I didn't see this earlier. This is quite right.

Even if the Mustang had 10 square meters cross sectional area (it's less than 8.9 m^2), it would only receive ~11kW of power in the most perfect conditions. Then throw in the <20% efficiency of solar panels, ignore the fact that you need windows, and you get about 2 kW. Even if you had 8 hours of perfect sunlight every day, that's only 16 kWh of energy, or maybe 5 miles of range.

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