[HN Gopher] Solar-Powered Electric Motors for EVs That Never Plu...
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Solar-Powered Electric Motors for EVs That Never Plug In
Author : mfiguiere
Score : 12 points
Date : 2023-08-18 19:08 UTC (3 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| BHSPitMonkey wrote:
| The newest Prius has a solar roof option, which in good
| conditions seems like it can reclaim a few miles of driving range
| per day. We're a far cry from "never plug in", I think.
| lm28469 wrote:
| It's more of a "unlimited AC when parked" than a "unlimited
| range" type of thing
| tootie wrote:
| It seems like an incredibly useful tool for avoiding being
| stranded but I expect we're many years away from a vehicle that
| run optimally on solar power even in a desert.
| jackmott42 wrote:
| It doesn't help with being stranded on any normal car. Better
| off walking.
| K0balt wrote:
| The energy that they could harvest from that panel would move an
| electric bicycle or scooter nicely around 15km/hour on flat
| ground.
|
| It would give you 5-7 minutes in a small electric car with a full
| days charge. 3-5 minutes in a regular electric car.
|
| You might possibly get as much as an 45 minutes with an electric
| cargo trike or one of those tiny 2 seat cars with the 1500w drive
| train.
|
| So sort of can work if you aren't meaning "car" in the
| contemporary sense of the word.
| hyperhello wrote:
| Nothing has been built or planned to be built, it's just someone
| proposing the idea.
| grecy wrote:
| I wish we could charge modern EVs directly from Solar/DC.
|
| This couple [1] are driving right around Africa in an EV powered
| from solar panels they're carrying with them, and they're using a
| prototype _very_ expensive and heavy solution to get the direct
| DC charging to work.
|
| I'm thinking of doing something similar, but I can't figure out
| how I'll do it without running around 400Ah of 48V Lithium
| battery. The panels can charge that using a regular old MPPT
| charge controller (or two). Then I'll run a big inverter (5000W)
| from that to get to AC power, and plug a regular EV charger into
| that.
|
| Does anyone have a better solution?
|
| [1] https://www.instagram.com/4x4electric/
| elihu wrote:
| > The system relies on AI to optimize the solar array's output
| and operate the motor at 88 percent efficiency; real-world DC
| electric motors have efficiencies of 75 to 80 percent.
|
| Meanwhile AC permanent magnet motors like the ones used in recent
| EVs are typically somewhere around 95% efficient as long as they
| aren't too far outside their optimal RPM/power range.
|
| AC Induction and series-wound DC motors tend to be somewhere
| around 88%.
| hinkley wrote:
| What's the conversion efficiency of DC-AC these days?
| [deleted]
| awiejrta wrote:
| Seems like the only novel part of this is suggesting we use a
| neural network to plan something related to solar panel tuning?
| And then it seems like another case of using the fanciest
| possible method to get a paper published, because linear
| regression would probably work better and be easier to implement?
| And then there's the simple fact that you can't power a car with
| solar panels on its roof because 1sq-m of solar panels won't
| produce anywhere near enough power, unless you only plan on
| driving to the mailbox and back once every other day. Am I
| missing anything?
| filleokus wrote:
| A friend of mine has a solar panel on top of his old small
| hatchback. The car itself is petrol powered, but he has a
| surprisingly expansive 12V system all over the small cabin,
| including some Li-ion battery packs. This powers everything from
| a fridge to charging stations for go pro's and a raspberry pi.
| Before the solar panel he sometimes had to drive around the car
| just to recharge the li-ion batteries from the generator, but
| with the panel's it's essentially self sustaining.
|
| However, the difference between powering some random electronics
| and actually making any meaningful impact on EV power usage is
| two completely different beasts...
| mikeiz404 wrote:
| I'm going to avoid critiquing the title but incase this gets
| missed...
|
| > The team only created a virtual model, but building a working
| physical model could be a future step.
| PaulKeeble wrote:
| At 1m^2 for the panel and a top end panel its going to peak out
| at ~230W. In an hour that is 230 Wh. That is 230Watts during the
| peak hours of the sun assuming its angled to directly capture the
| sun, which it doesn't appear to be in their concept CGI. Its
| probably going to be less than that.
|
| The Zoe which is a small electrical car has a 100KW engine for
| acceleration purposes. It goes 4.5 miles using 1Kwh of power at
| 31 mph (20C). It will cover that distance in 9 minutes at that
| speed. 230Watt hours in an hour of charging is a very far way
| from the 6.9Kwh needed for an hour of driving and this is optimal
| conditions as people brake/accelerate and travel faster than 31
| mph.
|
| This design might reduce the cost from the grid a bit and be
| useful for camping and trickle charge a bit through the day if
| its in a car park etc. But its not enough to run even the
| smallest electrical car today, its an order of magnitude off and
| even with a 100% efficient panel the cars would need to be 7x
| more efficient than they are today, and electric cars are already
| a lot more efficient than combustion engines.
|
| It fundamentally doesn't add up as a concept.
| rbanffy wrote:
| Besides, it's probably a better idea to always extract peak
| power from the solar array to charge the battery and let the
| motor use it at its own peak efficiency.
|
| The math doesn't add up at all.
|
| But they did publish it (and it got some press buzz), so their
| goal was achieved.
| hn_throwaway_99 wrote:
| At this point, I think we should be willing to call out these
| ideas for being unhelpful distractions from what will really be
| needed to combat climate change. As you point out, the math
| just doesn't add up. Photovoltaics on car roofs is just a dumb
| idea, beyond perhaps some novelty charging of accessories (e.g.
| running the A/C on hot, sunny days).
|
| There was a good article recently (maybe it was Washington
| Post, can't remember), about what will _really_ be needed to
| combat climate change, and I thought it was pretty great. Did a
| great job of highlighting the things to focus on that can
| actually be built fast enough (e.g. overbuilding renewables
| generation, upgrading electrical grids, "electrify
| everything", etc.) vs what are just distractions that are too
| small (or slow to build out) to make a dent in what actually
| needs to happen. You could perhaps argue with the author on
| some of the details around the edges, but the main points were
| pretty unassailable in my opinion.
|
| These proposals that will never amount to more than a drop in
| the ocean aren't worth wasting time on, and worse than that,
| they can make people "feel" like they're doing something
| valuable when they really aren't (see: most plastics
| recycling).
| abdullahkhalids wrote:
| This recumbent electric bike [1] with solar panels as roof
| takes 11.8Wh/km (plus human pedaling) to go at a speed of 26.5
| km/h. So, one hour of biking, covering 26.5 km will consume 312
| Wh. So within optimization distance, you can perpetually run
| this bike on clear sunny days on the Sun's power alone.
|
| So, yeah, solar panels on vehicle works as a concept for for
| bikes, not for cars.
|
| [1] https://www.recumbent.news/2021/05/23/the-ultimate-
| tilting-s...
| aimor wrote:
| Ok but if it was 3 m^2 of panels and if the energy needed was
| 100 Wh per mile then it starts to look possible. That's
| Aptera's solar vehicle design. I'm not saying this is currently
| reality, but in this case 1 order of magnitude doesn't feel so
| insurmountable that we should dismiss the dream. The article is
| pretty clear EV applications are a longshot example.
| tppiotrowski wrote:
| A nice design would be: When you park the car, solar panels
| cover all the windows or open like flower petals from the
| roof for maximum power harvesting.
| NoLinkToMe wrote:
| Weird article.
|
| 1. It's a model in theory, nothing has been built yet.
|
| 2. The model is for a motor that's 88% efficient.
|
| 3. There's already motors built in mass-manufactured cars (e.g.
| Tesla) >90% efficiency.
|
| 4. The objective is to have a car that doesn't need to plug-in
|
| 5. Such cars already exist, but if you don't plug in you just
| can't go very far
|
| 6. You'll never be able to go very far with such cars, even if
| they achieve their aim of 88% or even 100%.
|
| 7. There's absolutely no detail on why this is technically novel,
| other than the buzzword of the day 'AI algorithm'
|
| 8. There's no technical expertise by the writer, who is an
| uncritical mouthpiece of the researchers, but also offers no real
| context as to what competing technology offers in comparison
|
| Why is this deemed relevant or interesting enough for HN?
| jackmott42 wrote:
| regarding #6:
|
| The Aptera can do pretty well on just solar charging, enough
| that many people could commute every day and never plug it in
| (if they can park it in the sun every day, which you can't)
| NoLinkToMe wrote:
| Agreed looks really cool. Would love to see this become the
| future of mobility.
|
| The one thing I hate about car culture is that people
| (logically) tend to buy the car that fits all their use-
| cases, even if some of those use-cases occur less than 5% of
| the time.
|
| For example, when I buy a car I want at it to be able to seat
| at least 5 people, ideally 6-8. And I want it to be able to
| carry my furniture if I want to buy some, and stuff I need
| for a camping trip.
|
| But if I look at the distribution of use cases:
|
| People: I seat 1 person 90% of my trips (e.g. daily commutes
| to work, groceries). I seat a single partner or friend 8% of
| my trips. And I seat a whole car 2% of my trips.
|
| Stuff: I buy on average 1 big piece of furniture a year, but
| typically can have it delivered. I buy 3 items 2nd hand
| online that I like to use a car for picking up. I move homes
| every few years and my car isn't really big enough.
|
| Camping: I spend 10 days a year hiking in nature, of which 2
| travel days.
|
| So all in all I'd be completely fine with an Aptera type of
| vehicle for all but about 20 out of 365 days, or about 5% of
| the time. On those days I need something bigger, a car, or
| even a van/truck.
|
| I honestly can't wait till we get to a place of seamless
| renting of vehicles you happen to need that day. Economically
| it should fundamentally be the cheaper option: sharing
| production & maintenance costs across multiple users, and
| increasing average time-in-use vs idle-time, should decrease
| average cost-of-usage for users. Plus it means you can rent a
| smaller & cheaper vehicle for 95% of the time, and rent a
| bigger & costlier vehicle 5% of the time.
|
| This should certainly be cheaper than everyone having a fleet
| of large vehicles 100% of the time, which sit mostly idle 90%
| of the day, and are mostly empty during the hours you are
| using it at partial capacity.
|
| Of course renting vehicles isn't seamless. They're not always
| available, near you, expensive etc. But every 5 years it's
| getting better. And once self-driving really arrives
| (supposing it does, for 90% of trips), I think it'll
| accelerate the move away from the PC or 'Personal Car', to a
| 'Mobility Pod on Demand' type of model. Perhaps Aptera like
| vehicles will remain as the minimum personal car for those
| 95% of trips that you do with 1 or 2 passengers.
| pengaru wrote:
| Aptera has a solar-charged reverse trike EV that manages some
| impressive range from a day's worth of LA sun. If the panels ever
| get closer to 100% efficiency it'd make a great little commuter
| for sunny locales.
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(page generated 2023-08-18 23:01 UTC)