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randomusername8472 t1_jbjyxbk wrote

Thinking about the maths of it, I reckon a car with current level solar panels built into the roof would be a serious suppliment to the energy required.

I'm in the north of England and the 2.5kW, suboptimal panels on my roof generate about 15kWh on a sunny day.

Going by the size of the panel, I reckon at leat 1kW of capacity could be embedded on the average car roof, boot and bonet.

So a sunny day would then provide 5-6kW. So that's like 15-20 miles of driving?

Obviously the car would need external energy for the most part, but I don't think that's an insignificant amount of energy. And considering a concern for electric cars is still range and availability of charge points, knowing that you can get free mileage just by parking in an unshaded location for a few hours would be a big selling point to me.

I imagine the electrics of it are the most difficult part though.

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Tenrath t1_jbk203p wrote

For a super efficient car your math seems about right. A gallon (~4L) of gasoline is roughly 33kW/h of energy, so 100-120 miles per gallon equivalent car is possible, but difficult (sorry for US units, that's how we measure car efficiency).

It may be good as a supplement like you said, or can possibly keep the AC running or something like that.

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aesemon t1_jbk7kzx wrote

Just so you know, when it comes to car efficiency the UK uses miles per gallon. Petrol stations however show prices by the litre, oh and we use miles and yards for distance.

TlDR: mpg is fine to use with us.

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randomusername8472 t1_jbk8xai wrote

Yeah I went off Google's estimate of electric cars tend to get 3-4 miles per kWh (which I guess will actually vary massively)

And the car panel will be less optimal as the panels will be flat. Although unlike roof panels you could potentially move the car around to stay in the sun for longer.

For me, this would actually be an ideal car. I need a car for where I live, but I only use it a couple of times a week and almost always journeys of 5-6 miles or less. I'd only need to charge the car from mains in the depths of winter!

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IDontReadRepliez t1_jbkvesv wrote

The amount of energy generated is lower than the loss of efficiency due to the added weight of a solar panel. It’s significantly more efficient to mount a solar panel on top of a pole wherever you spend the most time parked (house for personal vehicle, office for business vehicle).

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randomusername8472 t1_jbm65ts wrote

Hmm, going by Googling the weight of a Tesla (1600 - 2000kg), and going by the 100W camping solar panel I have that ways 3kg...

I could maybe fit 6 of these rectangles on the roof of a car, so 18kg for 600W. 600W would generate 3kWh/sunny day.

So we've increased the weight by 1%, and get about 5% extra range per sunny day.

Seems like a decent trade off? You could probably even offset the weight by reducing battery size a little, as you need to carry less charge if you can top up power as you go?

Self charging from solar allays the fear that if you can't charge your car you won't be completely stranded. Fitting solar charging stations everywhere is a different use case really.

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