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this post was submitted on 05 Dec 2023
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Here's a video of a camper van with traditional solar panels on the roof using a slide-out awning technique.
https://youtu.be/Ev5C9gf0zFc?si=97piy-3mV9TIsRlu
You might say that's impractical for regular use. Sure, it is, but your previous argument was that is was impossible due to physics, which the video clearly shows isn't physically impossible, so we're already much closer to a reality. I'm not saying it could drive forever without stopping or be the only power source. That's silly. But if it reduces the need to charge from a grid by X% it can be a useful technology. Go on now and tell me how it could never ever work.
A camper van. Which has electrical use for things besides turning a motor. Yeah, that's useful, but it doesn't exactly help your case.
Under optimal conditions, the sun gives us 1000Wh per square meter. Let's say you have a 100% efficient solar panel. A semi truck trailer has a max of 42 sq meters on top of its trailer. So you get 42kWh out of this.
It takes about 280kWh to keep a semi truck at cruising speed on the highway. Thus, in this most optimal scenario, it would give you an additional 15%. Even this assumes there is no additional aerodynamic drag from the panels, mounting hardware, or wiring. It wouldn't take much to completely blow that 15% away.
If it's a cloudy day, all of it is now deadweight, and now hurts more than it helps. If you don't drive on the equator, its output drops and it now hurts more than it helps. If you have solar panels that actually exist that do around 20% efficiency instead of 100%, it now hurts more than it helps.
I guess we could move the Earth closer to the sun. Won't help our global warming problems, though.
It also turns the motor bro, did you watch it?
Of course it does. Doesn't mean it's a good idea.
Did you math?
You first said is was physically impossible. I've shown you it wasn't and predicted you'd move the goal post from possibility to practicality. And you did. Thanks for proving that you don't really care about whether it could even possibly work, but just that you wanna dunk on excitement and be right on the Internet. Have a good day.
I never said this.
"There are physical limits at play to how much power this can provide. No amount of technological improvement can break them."
Also, the fact it powers the motor for the camper AND all the appliances and such just proves the viability that much more, as the extra power draw is still supported by the camper's solar power system.
Yes, there are physical limits. It cannot provide enough power to justify having it only for the purposes of turning a motor. A camper van can justify it because it has lots of uses for electricity besides turning a motor, and as long as you're paying the cost anyway, might as well connect it to the battery charging circuit.
You started this conversation with:
All things that primarily turn a motor. None of these are feasible to be powered this way.
Your physics isn't terrible but you're making absurd leaps into nonsence with the rest, you also don't seem to have practical awareness of trucking logistics.
Here's a thought experiment, if sticking news paper to the outside of your truck was proven to give a 5% fuel cost reduction how long do you think it would take before you see a truck covered in news paper? Probably hours at most, truck drivers don't like stopping to piss because the extra fuel required to accelerate to highway speeds cuts into their margins so you can be damn sure that if there was an inexpensive way to reduce the cost of charging their truck everyone will be on that.
Also trunks have a lot of stuff beyond the motor, security and logging systems for example as well as various forms of climate control. Also being able to leave a vehicle idle and have it's fuel slowly increase instead of decrease / denature is a huge thing in a lot of situations.
If course is not going to make a truck that can drive a heavy load without recharging but if its only going to cost the same as a paint coating and can supply a slow trickle then it'll be a very popular product.
Even more so for things like agricultural machinery, leasure vehicles such as campers and boats, or anything with large gaps between uses.
So let's think about how a hypothetical electric truck would charge throughout the day. Driver makes a 20 minute stop and there's a 350kW charger available (about the max of what's out there for this sort of thing right now). They'll get 105kWh of charge out of that.
The top solar panels I can find at the moment are 540W and take up 2 sq meters each. So a 42 sq meter can have 21 panels for 11kW. That's the power they'd be rated for in direct sunlight on a bright day.
Even if we assume they have that direct sunlight for 12 hours straight (they won't, not even in equatorial regions), they'll get 136kWh out of that per day. Only a bit more than what they'd get out of a 20 minute stop.
US regulations require that a driver take a 30 minute break after 8 hours of consecutive driving. I also understand that this rule is broken all the time, but I don't feel the need to pander to exploitative and dangerous behaviors on the part of trucking companies.
Then we get to the cost. Those panels will be around $5000 for the set, and there are significant labor costs involved, too. Call it $10k/trailer to save a 20-30 minute stop each day that the driver will probably take, anyway.
There's also significant weight added, which reduces how much cargo they can carry. The factor you're talking about in getting the truck back up to highway speed just got worse. The panels ones noted in OP would be extremely lightweight, yes, but they also cut the power delivered in half.
None of this can happen until the industry electrifies. Current electric semi trucks are barely suitable, and there needs to be some improvements in battery tech before they can be.
This idea doesn't even look good on paper with unrealistic assumptions made in its favor. Put the solar panels at the charging stations, not the trucks.
Or better, forget about long haul trucking and replace it with electrified rail. Mount the solar panels on racks above the trains, not on the trains.
And this technology is ideal for going over rail, road, parking areas and all that sort of stuff so of course it's likely to end up used in those places.
It's also almost certainly going to be painted onto truck roofs, RVs, trailers, boat decks, fencing, marquees, and just about everything else. We'll certainly see rolls of it carried in pretty much all groups that go camping or work in off grid locations - take the roll, steak out two corners then unroll it onto a sunny bit of ground and suddenly you've got twenty square meters of PV charging your vehicles, phones, laptops, and tools. Life boats with power to run desalination equipment and satellite communications will save many lives.
At a low enough price point it's worth it just to maintain charge in an ICE's starter battery when left idle and to power monitoring systems, for electric trucks it's a no brainer - free fuel and extended range for the cost of a paint job? It doesn't matter how little range it adds or how slow the fuel trickes in it'll become ubiquitous pretty much over night.
So you did say that. But you just told me you didn't. You're confusing. I also showed you a motor powered this way yet you say it isn't feasible. So I really feel like I'm done with this conversation. Good day.
Not my fault if you don't understand the difference between "impossible" and "infeasible".