Solar Ventilation Operation

I've never actually timed it, and in fact, not even sure if the time given in the manual isn't an estimate. I would think the delay has more to do with how long it takes for the car to heat up, and when the inside cabin temperature equals, or exceeds the outside, the system is activated. Whatever that time is, it does take minutes for the inside to heat up. It's not instantaneous, that's for sure. If it was, you would end up bringing in warmer outside air into the cooler cabin...and that would make no sense to do so.

IMO, the system works as intended (ie, it brings the inside cabin temperature down close to whatever the outside air temperature is). I can't say that my car ever felt uncomfortably hot after sitting hours in the hot sun....unlike prior cars that I've owned that did not have this solar cooling system.

 

Living in AZ I suppose you use the AC all the time. The solar package is a good option for you. I guess the engineers in Tsutsimi, JP think it takes 10 minutes for the conditioned air in the cockpit to heat up enough for the solar gizmo to effect vent-mode. Gotta love the Asian logic on this one.

 

Does anyone know why they didn't design the solar cells to charge the batteries when not powering the fan? Seems like a logical thing to do.

 

I'm sure the primary purpose of the solar roof is to prevent a closed car turning into an oven in hot sun. The delay makes sense in high temperatures. You don't want warmer air coming in before the cooling from the a/c has disappeared.

 

Can you ellaborate on your statement?

The solar panel turns into a (noise) transmitter? Do you have a link to some technical article?

What does this have to do with using the solar pannel to trickle-charge either battery in the Prius?

 

I think that's hogwash. people with large solar panels on their home wouldn't be able to listen to the radio in their home. Analog TVs would have static and cell phones would be inaudible (given the strength of the PV panels on homes compared to on the prius). Or it's no work the R&D time for toyota to figure it out. There are cars coming to market with PV on the roof, so if you follow Toyota's reasoning none of those cars would have radios (too much static and in reference to the Nissan Leaf and the Fisker Karma)

A non-bs answer is that it simply not powerful enough to do any good charging the battery (but it could trickle charge the 12-Volt). So I guess Toyota can spread FUD as good as anyother company

 

Maybe I have a noisy fan but I can usually hear the solar powered cooling operating when I approach the car. The 10 minutes thing cannot be true as I have often stopped and rushed into a shop to get a drink and when I come out a few minutes later I can hear the fan and feel the breeze from it when I get back in.

As for having it charge the battery. How big would the panel have to be to fully charge the battery over a few hours. Even when I descend a long hill and manage to get the battery indicating fully charged the car does not suddenly decide to run on battery power alone unless I keep the speed well down. The benifit of a fully charged battery is fleeting thing.

So for me leave it alone doing what it does now. It has meant that I no longer have to go searching for a car parking spot under a tree as the combination of slightly open moonroof plus solar powered ventilation means over this summer just finished I have not returned to a sweltering hotbox like I have with past cars.

David

 

Ditto. I don't believe it for a second...

But even if there was some feedback that somehow coupled to the solar array that then acted like an antenna to cause FM inteference, surely Toyota could put a choke in the line to filter out the appropriate frequencies?

At the very least, answers like this make me doubt the credibility, and/ or honesty of toyota engineering.

 

As I mentioned in another post, I suspect the 10 minute delay that another poster reported, is an estimated average delay time. The point is - it's not instantaneous once the car is turned off. My guess is the time delay is related to how long it takes for the inside of the car to get hotter than the outside.

As far as the solar cells charging up the battery. I think most of us are referring to trickle charging the 12V battery, and not the much larger traction control battery. Given that there has been a lot of concern from posters about their 12V battery going dead after lengthy stays at the airport (for example), being able to trickle charge the 12V battery when not in use for extended periods would be a very nice feature, IMO.

 

The slick lit says that the solar ventilating fan starts up after the interior temp gets above 68F, not hotter than the outside. I agree though that in full sun the inside can get hotter than the outside and who'd care if it was only 68F outside anyway?

sideman59

 

I'm no EE.

I really wish I could find the post where someone here on PC I recall talked about the cost of components to get rid of the interference being way too high. I thought it was something along those lines.

http://priuschat.com/forums/gen-iii...panels-charge-hv-battery-pack.html#post997988 talks about the output.

 

My prius makes a noise when I approach it, solar fan on or off (and its usually no running in the parking garage.. no sun and all). I think its just a startup noise it makes getting ready for you to start the car when the key gets in range. You'll notice the lights come on too.

 

I'm in Orlando where it's always sunny and can get pretty hot too. The SR system keeps the car from getting very hot. I have my windows tinted and use a heat shield.

I believe the delay is for the SR to get enough energy to run the fans. I've sat in the car and the system will start and stop after a few seconds for a couple of times. After a little while it will run. I've never found the interior to be as hot as my previous car's interior did.

Even though it pulls the outside air, which is hot, it's still not as hot as a closed car parked in the sun would have been. I'm very satisfied with it.

 

I am an EE. The cost of removing interference from a battery charger driven by the roof PV array is not the limiting factor. It is the cost verses benefit verses development schedule that killed it. All companies have finite resources, even big ones like Toyota. Product decisions are being made constantly that weigh the costs and benefits for each development project. Apparently Toyota took a quick look at using the PV as a charger, but when they ran into some interference issues they decided it wasn't worth the effort.

This isn't to say that it's a big problem, or even a costly problem, but simply a problem that Toyota didn't believe they needed to address at this time. Stuff like this happens all of the time in the engineering world.

Tom

 

Agreed about the trade-offs and cost/benefit. We make these same decisions all the time in software development.

IIRC, someone here on PC went into the types of components needed (the explanation seemed reasonable) and mentioned their cost. I wish I could find the post.