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The advantage is the convenience of not even needing to plug in at all. Quit thinking of solar cells as an expensive, limited commodity. They’re cheap. Cheaper

The advantage is the convenience of not even needing to plug in at all. Quit thinking of solar cells as an expensive, limited commodity. They’re cheap. Cheaper literally than glass. About 10¢ per Watt at the cell level.

coryrc 4y ago
But you still have to plug in. Solar panels on a car will not make enough energy to run the vast majority of cars even if parked always in the sun. And for the few it could, you're using it so little what's the point of even having it?
- Robotbeat 4y ago
  8 hours in the Sun is good enough for 2 hours of driving, according to that blurb. That’s like 100 miles of range added per day, and the battery can buffer multiple days. Who drives 700 miles per week? Maybe 10%? Aptera’s car charges 40 miles per day, which is the same as the average American’s round trip commute (and can buffer during the weekend as well). The overall end point for solar charging is you’re charging enough that you don’t have to plug in unless you’re going on a road trip. I don’t know why it is hard to understand the basic idea or value of this. Most working people commute by car, and this concept would potentially allow all of the commuting miles by most people to be handled by the Sun. Home charging just no longer required. For sunny parts of the world (where people don’t park in garages, where they could plug in), that’s pretty awesome.
  - coryrc 4y ago
    > 8 hours in the Sun is good enough for 2 hours of driving, according to that blurb. That’s like 100 miles of range... Nope! They might want you to think that with misleading wording, but you'd be lucky for 2 hours of driving at 12 mph. And, again, that's only if the car gets full sun the entire day. At those distances, just get an electric bicycle. EDIT: I don't know what blurb you refer to, but my search engine says https://sonomotors.com/en/sion/ https://sonomotors.com/en/sion/ used to say "on average 112km/week".
    - Robotbeat 4y ago
      It was jvanderbot’s quip: “Yeah, if the panels are so efficient that 8 hrs of sitting can charge 2 hrs of driving, then just put those panels on your roof and wire them into a garage charger.” Generally, it helps to take comments in context… In his hypothetical, that’s clearly more than enough for the average person’s commute. And even if it isn’t quite enough, it could reduce the frequency you need to make trips to a fast charging station (effectively like having a twice as large of a battery), if you cannot charge at home. Charging stations usually are substantially more expensive than residential, maybe 3-4 times the price, and residential is 4 times the price of utility scale solar power (due to buffering and distribution, etc). So there’s a good financial case for it if you can get the cost low, plus you have the added convenience. Sono’s solar wasn’t very good. Lightyear and Aptera’s ability to add up to 40 miles per day is pretty useful… if they can get the cost down.
      - sokoloff 4y ago
        > Generally, it helps to take comments in context… That’s true, but when the projection is off by roughly a factor of 10, it’s helpful to bring in the actual data.
  - nradov 4y ago
    Aptera is lying. There is no way that a typical driver will get 40 miles per day of solar charging with the panels that they're using.
    - Robotbeat 4y ago
      Typical driver? Typical Aptera driver? Possibly… Keep in mind an Aptera has the volume and weight and frontal area more comparable to a covered bicycle or golf cart while its top surface is mostly the same as a normal car. So even if regular cars can’t do it, an Aptera maybe can. If a Model 3 can get 4 miles per kWh, I can believe an Aptera can get 10miles per kWh, as it has only 2 seats (not 5), and is extremely streamlined. Top surface of an Aptera is about the same as a Model 3 (8m^2 if you treat it as a rectangle), and all of the top part would basically be covered with solar cells. (Even the front window would have cells on the dash to collect the sunlight going through it.) if the total full factor of that rectangle is 45% cells, with 20% efficient cells… that’s 800 Watts. With 5 hours effective sunlight per day, 4kWh per day is doable in sunny locations. 40 miles per day. With just 800W, it’s okay if you’re using $2/Watt high efficiency conformal cells (as opposed to 10¢/Watt dirt cheap cells) as the cost is just $1600. That will pay back your Electrify America bill in just 2.5 years… or Supercharger (comparable to gas prices) in 3 years. Additionally, if you live in a place with crushingly high electricity prices but still has sun, you can pay back as well. And is more convenient than charging. I hope Aptera’s business works, as the idea has merit.
  - jvanderbot 4y ago
    Viability of 1hr per 4hrs charging aside... I think I had implicitly assumed that most people with commutes do not park outside (and thus would miss the valuable daylight charging hours, and would thus be better off charging a wallpack at home). But in hindsight, I think that's incorrect. _most_ people probably park outside at work, wouldn't they? those statistics would make or break a solar car.
    - Robotbeat 4y ago
      By far most, I’d say. And actually I’d say that parking garages and residential garages are both natural places for plug in charging. It’s street parking or vast (unlit) outdoor parking lots that would be a challenge for plug in charging, exactly the places that would work fairly well for solar car charging. So I think it’s a valid niche. The issue is it’s still annoyingly expensive to place solar cells on car surfaces, and really we should use those high efficiency multijunction cells. Tandem perovskite cells are very promising there, getting both high efficiency (over 30% and rising) and low cost. But conforming shapes to car bodies is also a challenge. However if those can be solved, it’d be great to have this option.
bluGill 4y ago
The only place where you can get useful power is the largest RVs. As long as you can legally make them (length as almost 0 effect on wind resistance), cover the roof and sides with solar panels (knowing that one side is always in the shade). Note that I said RVs not semi trucks. Semi trucks are meant to be driven all day (11 hours per day, though the law is more complex). Many RV drivers never drive that long in a day, and so we get a lot more stopped time where solar is charging batteries. Also we should assume that because space limited and they want a lot of power the person doing this paid extra for the highest efficiency panels, while less efficient ones are more cost effective for fixed installations.
- Robotbeat 4y ago
  The question really is only whether the solar cells pay for their weight and cost in the electricity they generate. I think the answer can be a qualified yes, depending on technology.
  - bluGill 4y ago
    Fixed mount solar panels connected to the grid are more cost effective. You need less because you mount them at a reasonable angle and ensure they are not shaded: you immediately get at least twice as much power for the $ vs on attached to something moving down the road. Probably more as since efficiency isn't critical when you can just buy a few more cheap panels and put them up for less than the more expensive ones you need to get useful power from the limited space on a moving vehicle. The grid also means that we can pipe energy around, so if your panels are shared the ones next door (next state...) can deliver power.
    - Robotbeat 4y ago
      It costs about 35¢/kWh to charge at a Supercharger location (comparable to gas price). Electrify America charges 48¢/kWh. For people who can’t charge at home or whatever, solar car charging could be a huge benefit, and it doesn’t matter in that calculation that utility scale solar is theoretically at like 4.4¢/kWh. Optimal angle, etc, is just a much smaller effect. Rolled into the price difference above: there’s the cost of buffering the solar power to be charged at the right time, needing land for the solar panels, needing land for EV chargers, EV charging equipment, charge/discharge from storage, conversion inefficiencies, etc.

coryrc 4y ago

But you still have to plug in. Solar panels on a car will not make enough energy to run the vast majority of cars even if parked always in the sun. And for the few it could, you're using it so little what's the point of even having it?

Robotbeat 4y ago
8 hours in the Sun is good enough for 2 hours of driving, according to that blurb. That’s like 100 miles of range added per day, and the battery can buffer multiple days. Who drives 700 miles per week? Maybe 10%? Aptera’s car charges 40 miles per day, which is the same as the average American’s round trip commute (and can buffer during the weekend as well). The overall end point for solar charging is you’re charging enough that you don’t have to plug in unless you’re going on a road trip. I don’t know why it is hard to understand the basic idea or value of this. Most working people commute by car, and this concept would potentially allow all of the commuting miles by most people to be handled by the Sun. Home charging just no longer required. For sunny parts of the world (where people don’t park in garages, where they could plug in), that’s pretty awesome.
- coryrc 4y ago
  > 8 hours in the Sun is good enough for 2 hours of driving, according to that blurb. That’s like 100 miles of range... Nope! They might want you to think that with misleading wording, but you'd be lucky for 2 hours of driving at 12 mph. And, again, that's only if the car gets full sun the entire day. At those distances, just get an electric bicycle. EDIT: I don't know what blurb you refer to, but my search engine says https://sonomotors.com/en/sion/ https://sonomotors.com/en/sion/ used to say "on average 112km/week".
  - Robotbeat 4y ago
    It was jvanderbot’s quip: “Yeah, if the panels are so efficient that 8 hrs of sitting can charge 2 hrs of driving, then just put those panels on your roof and wire them into a garage charger.” Generally, it helps to take comments in context… In his hypothetical, that’s clearly more than enough for the average person’s commute. And even if it isn’t quite enough, it could reduce the frequency you need to make trips to a fast charging station (effectively like having a twice as large of a battery), if you cannot charge at home. Charging stations usually are substantially more expensive than residential, maybe 3-4 times the price, and residential is 4 times the price of utility scale solar power (due to buffering and distribution, etc). So there’s a good financial case for it if you can get the cost low, plus you have the added convenience. Sono’s solar wasn’t very good. Lightyear and Aptera’s ability to add up to 40 miles per day is pretty useful… if they can get the cost down.
    - sokoloff 4y ago
      > Generally, it helps to take comments in context… That’s true, but when the projection is off by roughly a factor of 10, it’s helpful to bring in the actual data.
- nradov 4y ago
  Aptera is lying. There is no way that a typical driver will get 40 miles per day of solar charging with the panels that they're using.
  - Robotbeat 4y ago
    Typical driver? Typical Aptera driver? Possibly… Keep in mind an Aptera has the volume and weight and frontal area more comparable to a covered bicycle or golf cart while its top surface is mostly the same as a normal car. So even if regular cars can’t do it, an Aptera maybe can. If a Model 3 can get 4 miles per kWh, I can believe an Aptera can get 10miles per kWh, as it has only 2 seats (not 5), and is extremely streamlined. Top surface of an Aptera is about the same as a Model 3 (8m^2 if you treat it as a rectangle), and all of the top part would basically be covered with solar cells. (Even the front window would have cells on the dash to collect the sunlight going through it.) if the total full factor of that rectangle is 45% cells, with 20% efficient cells… that’s 800 Watts. With 5 hours effective sunlight per day, 4kWh per day is doable in sunny locations. 40 miles per day. With just 800W, it’s okay if you’re using $2/Watt high efficiency conformal cells (as opposed to 10¢/Watt dirt cheap cells) as the cost is just $1600. That will pay back your Electrify America bill in just 2.5 years… or Supercharger (comparable to gas prices) in 3 years. Additionally, if you live in a place with crushingly high electricity prices but still has sun, you can pay back as well. And is more convenient than charging. I hope Aptera’s business works, as the idea has merit.
- jvanderbot 4y ago
  Viability of 1hr per 4hrs charging aside... I think I had implicitly assumed that most people with commutes do not park outside (and thus would miss the valuable daylight charging hours, and would thus be better off charging a wallpack at home). But in hindsight, I think that's incorrect. _most_ people probably park outside at work, wouldn't they? those statistics would make or break a solar car.
  - Robotbeat 4y ago
    By far most, I’d say. And actually I’d say that parking garages and residential garages are both natural places for plug in charging. It’s street parking or vast (unlit) outdoor parking lots that would be a challenge for plug in charging, exactly the places that would work fairly well for solar car charging. So I think it’s a valid niche. The issue is it’s still annoyingly expensive to place solar cells on car surfaces, and really we should use those high efficiency multijunction cells. Tandem perovskite cells are very promising there, getting both high efficiency (over 30% and rising) and low cost. But conforming shapes to car bodies is also a challenge. However if those can be solved, it’d be great to have this option.

bluGill 4y ago

The only place where you can get useful power is the largest RVs. As long as you can legally make them (length as almost 0 effect on wind resistance), cover the roof and sides with solar panels (knowing that one side is always in the shade). Note that I said RVs not semi trucks. Semi trucks are meant to be driven all day (11 hours per day, though the law is more complex). Many RV drivers never drive that long in a day, and so we get a lot more stopped time where solar is charging batteries. Also we should assume that because space limited and they want a lot of power the person doing this paid extra for the highest efficiency panels, while less efficient ones are more cost effective for fixed installations.

Robotbeat 4y ago
The question really is only whether the solar cells pay for their weight and cost in the electricity they generate. I think the answer can be a qualified yes, depending on technology.
- bluGill 4y ago
  Fixed mount solar panels connected to the grid are more cost effective. You need less because you mount them at a reasonable angle and ensure they are not shaded: you immediately get at least twice as much power for the $ vs on attached to something moving down the road. Probably more as since efficiency isn't critical when you can just buy a few more cheap panels and put them up for less than the more expensive ones you need to get useful power from the limited space on a moving vehicle. The grid also means that we can pipe energy around, so if your panels are shared the ones next door (next state...) can deliver power.
  - Robotbeat 4y ago
    It costs about 35¢/kWh to charge at a Supercharger location (comparable to gas price). Electrify America charges 48¢/kWh. For people who can’t charge at home or whatever, solar car charging could be a huge benefit, and it doesn’t matter in that calculation that utility scale solar is theoretically at like 4.4¢/kWh. Optimal angle, etc, is just a much smaller effect. Rolled into the price difference above: there’s the cost of buffering the solar power to be charged at the right time, needing land for the solar panels, needing land for EV chargers, EV charging equipment, charge/discharge from storage, conversion inefficiencies, etc.