4 ms·

I don't think that area (of solar panels) would be sufficient to generate any serious charge. Good sun in an ideal case is around 1kw/m2. Whereas, a scooter ou

I don't think that area (of solar panels) would be sufficient to generate any serious charge. Good sun in an ideal case is around 1kw/m2. Whereas, a scooter output will be around 10kw (?). So naturally depends on how much area you really want to invest in. But I'd say 1m2 would be the maximum for a fold-out on a scooter. With the losses, less ideal sun, the weight of the batteries and the solar panels - not sure this would add up as a viable solution... You'd need to be charging for a day or two just to get an hour's output. A plug-in option probably more viable.

stcredzero 18y ago
An engineer in Michigan did exactly what was just proposed: http://www.treehugger.com/files/2005/04/don_dunkees_diy.php http://www.treehugger.com/files/2005/04/don_dunkees_diy.php I imagine that in southern California or Arizona, the thing would get substantially more than a 1/2 charge during the day. Depending on the battery chemistry, this could save a heck of a lot of battery life, even if it didn't provide enough to eliminate plugging in at night.
- jwilliams 18y ago
  1/2 charge on a summer's day. So less if it's cloudy and less if it's winter. Maybe a lot less, maybe 40%. A 1/2 charge seems to be about 1.2kwh. The EVT is rated at 1.5kw. So you might get an hour out of that. Anything more powerful (a typical scooter will be 5-10kw) and you're taking 20,30 minutes a day - with ideal sun. So, if anything, my previous math was conservative. Anyway - I'm not disagreeing with the principle - just saying I think there are better ways of going about it... I'd say, just stick with the plug-in and put the solar panels on your house.
  - stcredzero 18y ago
    I think this guy's commute was about 20 minutes. For high density environments like cities, everyone spreading out their folding solar panels on their parked scooters would be problematic. (I need to post my Florence Italy pics. A line of parked scooters as far as the eye can see -- literally.) So solar panels on the roof of the workplace also look good.
ivankirigin 18y ago
The model would be quick trips, rarely more than 30 minutes. Parking for the day in a lot at work, for example, would be more than enough to get home. I'd also want a plug-in option for nighttime charging. I think 1m2 is a very low estimate. Keep in mind I'm describing a covered bike. I live in Massachusetts, where it should be a crime to buy solar panels, given the dearth of sun. If I lived in SoCal, Nevada, or Arizona, this project would be very workable.
- jwilliams 18y ago
  If you're commuting like that, then just put the panels on your house - and plug the bike in. Having the portability of the solar panels doesn't seem necessary if it's just a down-the-road commuter.
DaniFong 18y ago
My calculations (http://daniellefong.com/2008/11/15/tick-tock/ http://daniellefong.com/2008/11/15/tick-tock/) give about 4 kwhr per 100 miles of city driving without regenerative breaking at about a 70% efficiency. Most of the US ranges between 2 to 4 kwhr a day of impinging sunlight - let's call it 3. High efficiency PV panels are about 30% efficient, so this is about 1 kwhr per m^2 of charge per day. This would give about 25 miles of city driving, which is well in the range of many urban commutes, but not most. To do better you need regenerative braking or higher efficiencies or more solar panels or all three.
- jwilliams 18y ago
  Thanks! So if you add in the weight of the panels, and the occasional patch of cloudy days - I think it might be a bit marginal... Would you agree? I hadn't really considered regenerative braking. I can see how it would be useful in a place like San Francisco, but I'd wonder how effective it would be in places like NY (where you need to slam on the brakes instead of just curb your speed). I recall reading about a mine in Peru (?) that used regenerative braking on all their hauling vehicles. They were all hooked up via a quite clever bumper-car style grid. When one was going downhill, it was helping power something going uphill. Apparently the regenerative braking in that case resulted >50% efficiency - which seemed like a very good figure to me. Do you know any figures for cars/bikes/scooters in more regular practice?
  - DaniFong 18y ago
    To make quick regenerative braking efficient, you need something other than batteries to store the energy -- they can't absorb that much power so quickly. They're working on ultracapacitors, which seem like an expensive solution to me. Our strategy, which is also used by so called hydraulic hybrids (in garbage trucks, most notably, which are constantly stopping and starting), is to compress air during braking: this can be done quite quickly and efficiently, and avoids conversion losses. We were expecting a cycle efficiency of between 70% and 80%. We're not working on vehicle technology at present, though.

stcredzero 18y ago

An engineer in Michigan did exactly what was just proposed: http://www.treehugger.com/files/2005/04/don_dunkees_diy.php http://www.treehugger.com/files/2005/04/don_dunkees_diy.php I imagine that in southern California or Arizona, the thing would get substantially more than a 1/2 charge during the day. Depending on the battery chemistry, this could save a heck of a lot of battery life, even if it didn't provide enough to eliminate plugging in at night.

jwilliams 18y ago
1/2 charge on a summer's day. So less if it's cloudy and less if it's winter. Maybe a lot less, maybe 40%. A 1/2 charge seems to be about 1.2kwh. The EVT is rated at 1.5kw. So you might get an hour out of that. Anything more powerful (a typical scooter will be 5-10kw) and you're taking 20,30 minutes a day - with ideal sun. So, if anything, my previous math was conservative. Anyway - I'm not disagreeing with the principle - just saying I think there are better ways of going about it... I'd say, just stick with the plug-in and put the solar panels on your house.
- stcredzero 18y ago
  I think this guy's commute was about 20 minutes. For high density environments like cities, everyone spreading out their folding solar panels on their parked scooters would be problematic. (I need to post my Florence Italy pics. A line of parked scooters as far as the eye can see -- literally.) So solar panels on the roof of the workplace also look good.

ivankirigin 18y ago

The model would be quick trips, rarely more than 30 minutes. Parking for the day in a lot at work, for example, would be more than enough to get home. I'd also want a plug-in option for nighttime charging. I think 1m2 is a very low estimate. Keep in mind I'm describing a covered bike. I live in Massachusetts, where it should be a crime to buy solar panels, given the dearth of sun. If I lived in SoCal, Nevada, or Arizona, this project would be very workable.

jwilliams 18y ago
If you're commuting like that, then just put the panels on your house - and plug the bike in. Having the portability of the solar panels doesn't seem necessary if it's just a down-the-road commuter.

DaniFong 18y ago

My calculations (http://daniellefong.com/2008/11/15/tick-tock/ http://daniellefong.com/2008/11/15/tick-tock/) give about 4 kwhr per 100 miles of city driving without regenerative breaking at about a 70% efficiency. Most of the US ranges between 2 to 4 kwhr a day of impinging sunlight - let's call it 3. High efficiency PV panels are about 30% efficient, so this is about 1 kwhr per m^2 of charge per day. This would give about 25 miles of city driving, which is well in the range of many urban commutes, but not most. To do better you need regenerative braking or higher efficiencies or more solar panels or all three.

jwilliams 18y ago
Thanks! So if you add in the weight of the panels, and the occasional patch of cloudy days - I think it might be a bit marginal... Would you agree? I hadn't really considered regenerative braking. I can see how it would be useful in a place like San Francisco, but I'd wonder how effective it would be in places like NY (where you need to slam on the brakes instead of just curb your speed). I recall reading about a mine in Peru (?) that used regenerative braking on all their hauling vehicles. They were all hooked up via a quite clever bumper-car style grid. When one was going downhill, it was helping power something going uphill. Apparently the regenerative braking in that case resulted >50% efficiency - which seemed like a very good figure to me. Do you know any figures for cars/bikes/scooters in more regular practice?
- DaniFong 18y ago
  To make quick regenerative braking efficient, you need something other than batteries to store the energy -- they can't absorb that much power so quickly. They're working on ultracapacitors, which seem like an expensive solution to me. Our strategy, which is also used by so called hydraulic hybrids (in garbage trucks, most notably, which are constantly stopping and starting), is to compress air during braking: this can be done quite quickly and efficiently, and avoids conversion losses. We were expecting a cycle efficiency of between 70% and 80%. We're not working on vehicle technology at present, though.