Solar Cells on Cloudy Days

[kevinmurray]

How much do cloudy days affect the solar cells on the roof? I live near Tacoma, WA and was wondering if that's a factor up here for powering the heating/cooling system. I can't wait to have this car available in my area.

[KarenRei]

A lot, but if it's cloudy, you're not going to have a greenhouse effect in your car ;)

[kevinmurray]

That's true, but what about heating on cold, cloudy, rainy days? Will that be impaired?

[pk-sd]

That's true, but what about heating on cold, cloudy, rainy days? Will that be impaired?

That is also my concern. It does get cold during winter even here in San Diego. I am willing to occasionally take some the energy from the main battery to keep me warm.

[KarenRei]

AFAIK, Aptera's not designed to deal with that any more than a traditional car is.

[pk-sd]

AFAIK, Aptera's not designed to deal with that any more than a traditional car is.

In traditional car I can make it nice and toasty inside on a cold, cloudy, rainy day. If Aptera is getting its energy form solar panels alone, Its not going to happen. So forget about "any more than a traditional car" it might actually be "no where near a traditional car" to that respect. But I am sure, engineers that can design sun an innovative car, can also solve this small problem.

[3-4-me]

The solar panels run a fan that pulls outside air through the cabin while it is parked.
They also supplement charge to the pack.(I wouldn't count on the solar panels to recharge very quickly though.)
There is also an A/C unit and a heater. Both run of the battery pack.

[The Bat Cave]

If you wrap a coiled metal tube around the aptera's drive motor and pump liquid through it, this could be a free source of heat, also it would help the motor last longer. The downside is that it further complicates the design with more stuff to maintain.

[KarenRei]

(Un?)fortunately, electric motors are very efficient compared to gasoline engines -- 85-90% in typical operation (and 95% peak efficiency) in a good electric motor. So there's not nearly as much waste heat.

[GCustom]

wrap the coils around the charging circuitry and store the heat for later Ala Prius II (3rd gen) in a flask.

[KarenRei]

Hmm, let's do some math. Let's say 85% system efficiency, 10kWh over 2 hours. That'd be 750W of heat output. Of course, you couldn't scavenge it all -- perhaps you might get 500W of it. While that's not a *ton* of waste heat, and certainly nothing compared to what a gasoline engine dissipates, and it may not be enough on its own to heat up a cold car, it's not an irrelevant amount.

[LQUAN]

Run a water coil around the motor to collect heat for the cabin? You can run the same coil to your seats, after about 10 minutes, you will have a couple of warm seats. But then I am sure your body heat can warm up your seat much faster. Heat produced by Aptera electric motor is not worth collecting. For crying out loud, the motor doesn't even need a cooling fan to operate.

[pk-sd]

...... For crying out loud, the motor doesn't even need a cooling fan to operate.

You can say Aptera is a victim of its own success.:eek:

[GCustom]

Hmm, let's do some math. Let's say 85% system efficiency, 10kWh over 2 hours. That'd be 750W of heat output. Of course, you couldn't scavenge it all -- perhaps you might get 500W of it. While that's not a *ton* of waste heat, and certainly nothing compared to what a gasoline engine dissipates, and it may not be enough on its own to heat up a cold car, it's not an irrelevant amount.
I'm just thinking about the temps my 9 cell laptop battery can reach during charge/discharge (mostly charge)

[3-4-me]

I have no idea of the efficiency of the heat pump that Aptera is using.
It looks to be pretty well designed though.(maybe I'm just mesmerized by the red/blue LEDs that correspond to the temp desired:D )
I think I'll stick to worrying about overall width and HOV lane usage:p

[appyfan]

Hey guys I know this may sound like a really stupid question... But what if I was in the middle of the desert with no outlet in sight, and I had the electric version.

If I understand correctly, the solar panel on the roof "augments" the climate control and (kind of?) recharges the batteries. So exactly how long would it take if I were to rely on the cells to charge up my car?

Just curious... I love solar cells. :D

[pk-sd]

Hey guys I know this may sound like a really stupid question... But what if I was in the middle of the desert with no outlet in sight, and I had the electric version.

If I understand correctly, the solar panel on the roof "augments" the climate control and (kind of?) recharges the batteries. So exactly how long would it take if I were to rely on the cells to charge up my car?

Just curious... I love solar cells. :D

I too would like to see solar cells charge the main battery even for the Type-H. That way, while I am at work for 9 hours, my battery is getting charged automatically, and I will not have to charge it at home overnight. It would save some electricity at home.

[LQUAN]

Hey guys I know this may sound like a really stupid question... But what if I was in the middle of the desert with no outlet in sight, and I had the electric version.

If I understand correctly, the solar panel on the roof "augments" the climate control and (kind of?) recharges the batteries. So exactly how long would it take if I were to rely on the cells to charge up my car?

Just curious... I love solar cells. :D

If you are driving an electric version, don't venture into the desert or nomansland. And if you must, carry a fully charged cell phone. If your cell has no signal, then start to tinker with the car's automatic cooling system. Disconnect the automatic cooling system (fans) to allow more juice produced by the solar panel to go to charging the battery. But with the given microsize solar panel, I hope you carry enough food and water for 3 or 4 days.:D

[KarenRei]

You're not going to like the answer, but it is "weeks". Solar, sadly, is not a very energy-dense source, even on bright sunny days. The Aptera takes 80Wh/mi@55mph. Your solar capacity factor on a fixed plate, just assuming it's at an ideal angle, won't get any better than 25% or so over the course of a day. And the cell will have ~20% or so efficiency. Multiply that by the most energy that ever usually hits the surface (1000W/m^2), and you get 50W/m^2, meaning one day of charging in a sunny location with an ideal angle will get you 15 miles of range per square meter. The Aptera probably has perhaps a third of a square meter of solar panels, so that's about 5 miles per day. In these optimal conditions.

Sorry -- it's unfortunate, but you need a dozen or so square meters of solar panels to fully charge an Aptera each day in normal conditions -- less on sunny days, more on less sunny days.

Back to driving through the desert: If you're going a long distance or into dangerous territory in a Typ-1e, just bring a portable generator and a 5 gallon gas can.

[appyfan]

Hey 5 miles a day is better than no miles a day! That doesn't seem too bad considering it would be an emergency situation..:o

[KarenRei]

Yeah, but you could push it faster than that ;)

[butter]

Hmmm... considering its low CD, and just for fun let's assume the desert road is very flat and straight, and that it actually isn't a totally scorching hot day... it would be interesting to see how far a two-person-party could push-and-coast the Aptera (with someone inside steering), sort of like a giant version of a skateboard.

[bobjohnson]

What about some kind of human powered hand crank?

I'm sure some smart person out there could figure out a method of harnessing a hand crank to charge the battery for emergencies. It would certainly charge much faster than the solar panels, and wouldn't be much of a hassle to keep one in the car if it's small.