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Comment by Neil44 | Hacker News Reader

I wonder how they got to 450 miles a day on solar. I remember the Prius solar roof option would only give you a couple of miles a day in ideal circumstances. This camper has more panels but that’s still a bit jump to 450 miles.

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That 450 miles will also use up the electricity stored in the 60kWh battery. So you'd get one day to travel 450 miles and then either have to plug in to charge, or use the solar panels to regain range. They mention being able to gain a full charge in 2-3 days if stationary, which is impressive. Given the 60kWh battery they must be getting around 20kWh/day from the panels.

It sounds like they are averaging around 60 miles/day on their road trip. Given the regular RV loads they will have for cooking and lighting, in addition to cloud days, it seems like they are fully utilizing their solar gain.

I remember a lecture at university where we assumed a cars body was 100% covered in solar panels and that the sun was hitting all panels simultaneously and that the panels were 100% efficient and the car was above the earths atmosphere and we calculated that the power produced was equivalent to 6HP or the size of a riding lawn mower engine. It was meant to show that physics forbade a solar powered car as we knew them.

Is it a limit on acceleration coupled with larger solar area that allows this?

I calculated a similar maximum horsepower to your own estimation (6.1 hp) when I used the average direct solar radiation (164 W m^2 @ 27 m^2 surface). This rose to 41 hp when using values for "a typical cloudless day at solar zenith" (1120 W m^2) [1]. The wattage will square when doubling each side, so if you were to double each length of the surface, you'd be up to 151 extremely hypothetical hp - just like the Honda Insight!

Back on planet earth, the most common solar panels have efficiencies between 15-20% [2]. Direct radiation is diminished by the cosine of the angle of solar tilt. It takes another ~2 hp to overcome drag at just 30mph [3]. Who knows how much this setup would weigh. You'd have to be Speed Racer's long-lost brother in Arizona to win a mid-summer dead-heat race at noon with a go-cart.

[1] https://www.newport.com/t/introduction-to-solar-radiation

[2] https://css.umich.edu/factsheets/photovoltaic-energy-factshe...

[3] https://web.archive.org/web/20190616063447/http://phors.loco...

Way more panels, as seen in this image [1] and shown on specs [2] as 17.5 m^2 of panels unfolded.

[1] https://images.prismic.io/solarehv/62d397ae-9839-4d31-b316-a...

[2] https://vita.solarteameindhoven.nl/about-show

OK but 5x the panels makes for 10-20 miles a day not 450. Also with the panels extended you would not be able to drive, so you would alternate driving and charging days.

Technology has advanced since the Prius solar roof, which was never a serious option to begin with.

By going downhill.

It’s the Netherlands.

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