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I was more referring to weather. I love the idea of this vehicle, and if it performs as advertised I could see myself using it. However - I wouldn't want to ba

I was more referring to weather. I love the idea of this vehicle, and if it performs as advertised I could see myself using it. However - I wouldn't want to bank on it charging during work to extend it's range every single workday. Overcast and rainy days happen almost everywhere, at least some times. Or I could be misunderstanding something about solar panels - do they continue to charge even without direct visible light? I don't know much about them.

pengaru 4y ago
> Or I could be misunderstanding something about solar panels - do they continue to charge even without direct visible light? I don't know much about them. They diminish output in proportion to the amount of light. In a charging situation where you require at least a certain voltage to push anything into the batteries, I presume it will just stop charging well before the panels are 100% dark.
Schroedingersat 4y ago
Their calculations include corrections for capacity factors due to weather. They are probahly a little generous about traffic conditions in some areas though. 40 miles at constant 30mph is very different to stop start hitting 30mph each block or to constant 70mph. A 100kWh battery is sufficient to average available energy for a 700W panel out over several weeks in summer at lower latitudes, and a month or so in worse conditions. The idea seems untenable until you consider that it's more like a big ebike than a car. It weighs a fifth as much as a tesla and has under a third of the air resistance.
marssaxman 4y ago
Solar panels don't care which direction the photons arrive from; they work fine in overcast conditions.
- wyre 4y ago
  >fine They are much less efficient however
  - marssaxman 4y ago
    Solar panels do produce less power on overcast days than in full sun, but they are actually more efficient, not less - like other semiconductors, they work better at lower temperatures.
    - wyre 4y ago
      Interesting! Thank you!
qqqwerty 4y ago
On one hand, I see where you are coming from. The vast majority of people overestimate the ability of solar to generate power. It requires a lot of surface area with good orientation to generate "meaningful" power, where "meaningful" is enough to power a typical house, a typical car, etc... But it is also possible to attack the problem from the other end. Instead of making more energy, make things more efficient. For example, my e-bike is incredibly efficient. A 100 watt solar panel with good orientation and exposure is likely sufficient to charge my e-bike for my (previous) 14 mile round trip commute (since covid I am WFH though). But that same panel would probably get you 1-2 miles in a Tesla (more likely 0 as you couldn't even push enough power to initiate a charge on the massive batteries). Seems like Aptera is coming at this from the efficiency end. There is an annual collegiate solar car competition and based on previous results you can get a pretty good upper bound of how many miles a "car-like" machine can travel on solar alone[1]. Based on those numbers, it looks like the multi occupant vehicles can get into the 80 miles per day range. This is on a track, going ~30 mph, so definitely not real world conditions. But one doesn't have to stretch their imagination too far to see how adding a few more creature comforts (i.e. vehicle weight, cabin and trunk space) and taking into account real world driving conditions, but also investing more time in aerodynamics and solar panels (the college kids in the solar comp are on a much lower budget) could result in a 40 mile/day estimate. I would probably guess that is on the high side, as Aptera has an incentive to push the numbers in their favor. But I couldn't certainly see how the numbers could be possible. Aptera has a somewhat checkered history, which is another issue entirely. But just from a quick gut check, nothing they are promising seems to be out right impossible. [1] https://www.americansolarchallenge.org/the-competition/2021-american-solar-challenge/formula-sun-grand-prix-2021/ https://www.americansolarchallenge.org/the-competition/2021-...

pengaru 4y ago

> Or I could be misunderstanding something about solar panels - do they continue to charge even without direct visible light? I don't know much about them. They diminish output in proportion to the amount of light. In a charging situation where you require at least a certain voltage to push anything into the batteries, I presume it will just stop charging well before the panels are 100% dark.

Schroedingersat 4y ago

Their calculations include corrections for capacity factors due to weather. They are probahly a little generous about traffic conditions in some areas though. 40 miles at constant 30mph is very different to stop start hitting 30mph each block or to constant 70mph. A 100kWh battery is sufficient to average available energy for a 700W panel out over several weeks in summer at lower latitudes, and a month or so in worse conditions. The idea seems untenable until you consider that it's more like a big ebike than a car. It weighs a fifth as much as a tesla and has under a third of the air resistance.

marssaxman 4y ago

Solar panels don't care which direction the photons arrive from; they work fine in overcast conditions.

wyre 4y ago
>fine They are much less efficient however
- marssaxman 4y ago
  Solar panels do produce less power on overcast days than in full sun, but they are actually more efficient, not less - like other semiconductors, they work better at lower temperatures.
  - wyre 4y ago
    Interesting! Thank you!

qqqwerty 4y ago

On one hand, I see where you are coming from. The vast majority of people overestimate the ability of solar to generate power. It requires a lot of surface area with good orientation to generate "meaningful" power, where "meaningful" is enough to power a typical house, a typical car, etc... But it is also possible to attack the problem from the other end. Instead of making more energy, make things more efficient. For example, my e-bike is incredibly efficient. A 100 watt solar panel with good orientation and exposure is likely sufficient to charge my e-bike for my (previous) 14 mile round trip commute (since covid I am WFH though). But that same panel would probably get you 1-2 miles in a Tesla (more likely 0 as you couldn't even push enough power to initiate a charge on the massive batteries). Seems like Aptera is coming at this from the efficiency end. There is an annual collegiate solar car competition and based on previous results you can get a pretty good upper bound of how many miles a "car-like" machine can travel on solar alone[1]. Based on those numbers, it looks like the multi occupant vehicles can get into the 80 miles per day range. This is on a track, going ~30 mph, so definitely not real world conditions. But one doesn't have to stretch their imagination too far to see how adding a few more creature comforts (i.e. vehicle weight, cabin and trunk space) and taking into account real world driving conditions, but also investing more time in aerodynamics and solar panels (the college kids in the solar comp are on a much lower budget) could result in a 40 mile/day estimate. I would probably guess that is on the high side, as Aptera has an incentive to push the numbers in their favor. But I couldn't certainly see how the numbers could be possible. Aptera has a somewhat checkered history, which is another issue entirely. But just from a quick gut check, nothing they are promising seems to be out right impossible. [1] https://www.americansolarchallenge.org/the-competition/2021-american-solar-challenge/formula-sun-grand-prix-2021/ https://www.americansolarchallenge.org/the-competition/2021-...