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Comment by LeonM | Hacker News Reader

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.

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> 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.

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