solar losses due to heat build up are a concern of mine. in my testing, the current can nearly be cut in half due to thermal buildup. will the aptera have any kind of solar cooling to keep the current at maximum? In the vehicle design I have been working on, the plan was to use passive cooling by creating a small pocket of space between the solar and the actual roof, with a simple adjustable louver system at the front of the vehicle and a vent at the rear. thanks so much.
On last Wednesday's conference call, Aptera's co-CEO's and founders discussed new details of their unique active cooling system. Rather than use a traditional radiator as all other ICE and EV's use, the Aptera uses "microfluidic channels" built into much of Aptera's skin panels. They did this to remove the significant aerodynamic drag caused by traditional radiators.
This is not unlike the way animals (like us) cool themselves by expanding their capillaries in their skin when they are overheated.
These liquid filled channels are in the roof, the belly and in its side panels. So the roof panels cool the solar panels to make them more efficient, warm or cool the batteries as required, and remove excess heat through the belly and side panels.
Chris Anthony mentioned you can sometimes feel that the side of the Aptera's skin is surprising warm. Steve Fambro added that in certain weather conditions you can see the microfluidic channels form visible patterns made by frost or condensation on the skin. (How cool is that! 8-) )
I wish I would have been able to make that call, however I was being interviewed at that time. It is so good to hear there will be a solar cooling system integrated into the body of the vehicle. Great engineering!
How does this solar cooling system affect the cost/ability to repair a fender-bender? Say a direct/small hit to the quarter-panel? Would body work be a dealer-only repair? Or does damage to the fluid channels translate to a 'total' of the car?
@arak_lea Good question! Have you seen the video of auto convention goers taking a sledge hammer to the body of the first gas powered iteration of the Aptera?
Check it out: [https://www.youtube.com/watch?v=bdqUTDCOGSs]
No one could damage it! - That body panel just flexed and bounced back with no more damage than a scratch that could be rubbed out or perhaps covered with a new vinyl wrap! If the hit was enough -- stronger than those many sledge hammer blows - strong enough to break that tough, flexible body panel and deploy the air bags - then at least the body panel would need to be replaced. The whole car would need to be carefully inspected, checking for battery damage, etc.
Once we see the results of the production vehicle crash tests we will have a much better idea of how much impact this beast can take.
It's a good idea to use microchannel heat exchange to collect heat from the solar panels. But what is not clear is how this heat is dissipated.
They have microchannels in the skin on the cooler sides and belly of the beast. They act as radiators to remove heat from the vehicle. It has been designed to work well to keep you comfortable at up to 125F ambient temperatures. Don't know any details about the other components of the system: heat exchangers, pumps, compressors, etc.
Good question and I am not sure.
I could share “other information “ that you may find useful but NOT your answer.😞
As you may know.... the solar array will also power an interior heat venting system for the vehicle itself, besides the Never Charge.
Understand Aptera is coming in on completing their Development vehicles soon, so spec should be available shortly.
The battery specs were ~ 0-120*F. The Dev vehicles would be tested with their final choice of batteries
Both my homes’ PV Solar Arrays were/are roof mounded and the brackets set them about 4-6” off the roof itself, so that did provide some passive cooling and the heat loss did not seem that bad. I am in solar zone 8 now and I am checking my production on my 7kWh system.... It is producing 6kWh per day on these partly cloudy, nearly 100*F summer days
I never clean my home PV solar panels and I am in an dry dusty desert
I would think most would clean there aptera frequently, for what that is worth on production 😉
Apetra’s website has their solar calculator.
I believe I read they had significant hrs of testing on the present Never Charge solar array on their simulation jig.
I assume all tested in sunny southern CA.
The decade old small solar array on their old 2e was mainly used for venting heat from those old 12 or so (?) prototypes
Just for reading... you may find this product interesting as to how they maintain the efficiency of the PV generation, with, tracking, passive cooling, self cleaning. Of course not for mobile use! It is $$$
Smartflower.com
I was going to investigate this but we have too many breezy days here, so it would be closing and reopening too frequently
The situation with solar on a vehicle that may be an issue is not the same as with a typical solar installation. typically there would be space for air to pass under the cells to allow for passive cooling. with a vehicle, there is no elevation between the solar and the roof, thus the heat build up. I will contact solar team Eindhoven and ask what they have done with their solar cars. seems almost necessary to allow for some type of cooling (to gain max efficiency). One of the men driving an ELF trike with a trailer I put together that has 600w of sun power cells on it has given me great feedback about this issue.
Einhoven doesn't use any passive cooling. They say
"When Stella's are at a standstill, they do not get any active cooling. They actually get quite hot! During driving, they are cooled by the wind, so no active cooling needed (at least not from our side)."
I wonder what kind of lifetime advantage to cell longevity and increased energy output could be had with simple passive cooling, or even better, a small fan to draw in cool air when there isn't enough wind to have a useful air exchange.
If, as Len mentioned, forced air cooling will be used to keep the cabin comfortable, doesn't that count as active cooling of the back sides of the solar cells?
@Harry Parker only if the cells are open to the cabin, which I am sure they are not since they need some sort of structure under them for support and to keep them from getting damaged by say, a 2x4 hitting the roof during loading into the car for example. The cells would need to have the least amount of insulation between them and the air circulation to have any noticeable effect on current loss prevention. They could however, be attached to one side of a semi-hollow honeycomb like structure that allows airflow, while keeping them safe from damage from inside and outside of the vehicle.
@Harry Parker I'm hoping that a lighter color roof would reflect more of the sun's rays and keep the solar cells cooler than a darker roof. My solar array is most efficient at 76 F.
with micro channels in the skin of the vehicle, how would you change out the fluid and ensure you purge all the air out of the system?
Good question. That will be in the Service Manual, which probably hasn't been written yet.
On my Chevy Volt, the battery cooling system also has many tiny cooling channels in the battery modules. It also has separate cooling system for the power electronics, as well as the standard engine cooling system, each with their own radiators and coolant overflow containers. That's 3 independent cooling systems, if you're counting. the cabin cooling system is part of one of those. The service manual says they each should be flushed every 5 years because the anti-corrosion additives in the coolant eventually breakdown with heat and time.
I learned on the Chevy Volt forums that the dealer uses special proprietary GM software to control the cooling system values and motors and a special vacuum pump to ensure that the system is completely flushed without leaving air pockets. It takes over an hour to perform under computer control.
The Aptera system will be less complicated (no engine loop), and hopefully doable without special equipment, using only the pumps built into the vehicle. At worse, you'll need to purchase or borrow a vacuum pump for the job.
@Harry Parker I don't think it's the engine loop that makes the coolant change on the Volt complicated. It's the other two cooling loops.
@srmarti Yes. It is the Volt's battery cooling loop that has all the tiny channels throughout the battery modules. Any air bubbles in there and the cooling doesn't happen. Then, Gooodbye battery!