50km a day in charge capacity is the absolute best-case scenario. In reality you should count on half of that.

What you gain in additional charge will offset the AC power draw you need to cool down your car after you parked it in the sun for a full day.

A more effective solution would be to have a carport with a solar panel roof (10~15m2) that way you have shade, affordable panels, and an actual charge capacity of about 50km. It doesn't move with the car, but since we are talking about work commute your car will probably be parked at the same location for 5 days/week during peak sun output.

Mind you that the panels used on the Toyota prototype are still very expensive. At current prices they probably don't make economic sense.

> A more effective solution would be to have a carport with a solar panel roof (10~15m2)

Right. Or from a pure economics point of view, put the solar panels literally anywhere else in the world other than on top of the moving vehicle that is sensitive to aerodynamics, weight and structural integrity. Deal with the small transmission losses from the grid. Rely on charging stations at home, work or other businesses. The last part is the only piece that isn't reliable at the moment, but is only getting more so.

Parent's point with the carport is that it would also keep the car from heating up in the sun. "Anywhere else" doesn't necessarily provide the benefits he's talking about.

Sure, build carports where they make sense, and put solar panels on roofs where those are economically worthwhile. There are not especially large synergies between solar power and carports compared to other permanent structures, it's just an example of something that is still superior to solar panels on cars.

To be fair, on top of moving vehicle is still better than under moving vehicles ala Solar Roads

Not only they got publicity and kick-starter funding they even got cobtracts from local government! And there are copycats also with government money.

Can someone explain this to me a bit? How one manages to not only promote such an obvious flawed idea to implement, but actually inspore others to copy them?

Are there any lesson to learn from that for projects that actually work?

>50km a day in charge capacity is the absolute best-case scenario. In reality you should count on half of that.

I'd count on even less than that. Industrial solar farms average a capacity factor of around 20-25%, dropping as low as 10%. And that's with farms built for maximizing sunlight. A car is likely to do far worse, especially when you consider imperfect conditions, and how frequently people park indoors. If it's a tossup between protecting my car from the elements, and getting a few miles a day of charge, I'm going to choose the former.

If you read the sentence closely, it's actually claiming ~25km/day of charging, to drive 50km 4 days a week.

I wish more people would respond to this comment rather than debate the benefits of putting solar on a ferry. Is there data on the avg commute distance in different cities? 50km seems like a significant distance and could cover a large number of commuters.

cars are used around 10000 km per year in Germany by what I found online. That’s around 30 km per day.

Americans drive around twice that much. The latest number I could find was 13,476 miles per year for the US.

I use my car for 6km per day, but I do 700km in a day on motorcycle on a weekend day.

Anecdotally 140km between Glasgow and Edinburgh (round trip) so it seems like inter-city commuting is probably out.

Virtually no one in the UK is doing this, this is an absurd answer.

80 miles (128km) a day is a pretty harsh commute I used to do, the vast vast majority are doing significantly less than this.

When I used to regularly visit Bristol, I got to learn quite a few that used to commute to London from Bristol and Bath surrounding areas.

The vast majority of people don't commute 140km a day.

That’s an extremely specific single example. Can we really usefully generalise from it? Maybe some cities are closer than these two?

Glasgow also has only 1201 annual hours of sunshine, less than 3.5/day. What a strange example to choose...

Anecdotally I live 8km from work (same city, Europe), making a 16km/day commute.

That seems on the high end of a traditional commute; given traffic that takes, what, nearly two hours each way?

I used to do 80miles (128km) a day with harsh traffic and that was 1.5 hours each way(40miles). so yes you are right it's much closer to 2hrs than 1hr.

It's closer to an hour, than it is to two.

You also need to remember that the Prius Prime has just a laughable battery capacity relative to a Tesla. Like less than a twentieth of the batteries.

Among other things this means you can meaningfully charge the Prius's battery from the solar hitting it on a daily basis, even though it would take weeks to fully charge a Tesla.

if you park and drive in the sun all day. No clouds, no garages, no trees, etc. It would usually be more sensible to put the panels on your roof, to plug your car into.

I think the appeal of solar panels on a car roof is that you don't need any infrastructure at all. Just park you car wherever and it automagically recharges.

But you cannot rely on that every day. On cloudy day it’s not going to help you. So while it maybe fine for a PHEV, I still think than having PV installations over every parking lot makes more sense.

>I still think than having PV installations over every parking lot makes more

If this was a planned economy I would agree and vote in the next party meeting to put chargers in every parking lot and power them with transparent PV over the parking spaces.

But since I live in a capitalist country I can't make other people invest tens of thousands of dollars just because it makes more sense than putting solar panels on my car. I mean, in some cases I still can, but there's a significant market for the people that can't effect such a change and have to make due with the less efficient solar powered car.

Exactly. Home ownership is at 64% in 2018 in the US. Solar roof installation requires landlord/HOA permission and permits in apartments/condo units. Lots of cars in the southeastern/southwestern US are parked in direct sunlight. At the very least, getting into an ambient temperature car is a great feeling in these places

There would be a lot of permits though, delays, etc. I like the idea of having smaller panels as one offs.

Unless you park in a garage, which a lot of people do.

And a lot of people don't. There's way more cars than there is garage space.

So everyone will park in the sun and not near trees or buildings.

Garage is just one example where there is no sun.

Yes, and since this is a product specifically marketed to people who live in the area of the world where 100% of parking spaces is shaded it's obviously a bad idea.

What if they instead sold it to people who usually park in non-shaded parking spaces? Would that work, do you think?

Parking garage at my office park doesn’t even have open-air spaces on the top floor: the deck is covered with solar panels.