Solar Roof - Does it work?

[Tideland Prius]

Originally Posted by PriusRos

I've only managed to "catch" it working two or three times in the 5 weeks since I bought it. Partly it's because it's rained a lot and been overcast recently, but there have been a number of sunny days when I've parked it in the sun.

Each time when I had "caught" the fans working, it was just for a few seconds before turning off. I had assumed that somehow I was always catching it at the end of its cycle. However, yesterday, when I returned to the car, the fans were not running. I decided to wait a little while and then I heard the motor starting and felt the fan running for a full..... 4 or 5 seconds... before switching off. That hardly seems enough time to do anything! It was a clear sunny day but not extremely hot, so the car interior wasn't that hot, but it hadn't been parked that long either.

Is it normal that the fan only runs for a few seconds at a time? Maybe I need to clean the roof off properly. I am parked under a tree at home so it gets a lot of stuff on it all the time. What should I finish it with after washing?

The interior wasn't hot. Wasn't that the point? It will cycle the fans if there isn't enough solar power for continuous operation. I've caught it doing a continuous operation (I stayed inside the car. That was the longest and hottest 10 mins of my life) and it worked. I stayed cooler once the fans were on.

[PracticalEfficiency]

I live in Oklahoma and the solar panel ventilation system has been working great. It's a huge difference getting into the Prius with some air already blowing in it. Although I simply got it because I wanted the nav system, the solar panel has been really nice to have.

[MataOrtiz]

Originally Posted by Tideland Prius

The interior wasn't hot. Wasn't that the point? It will cycle the fans if there isn't enough solar power for continuous operation. I've caught it doing a continuous operation (I stayed inside the car. That was the longest and hottest 10 mins of my life) and it worked. I stayed cooler once the fans were on.

Didn't know it got that hot in Canada...

[MataOrtiz]

Originally Posted by oxnardprof

A colleague at work has a SR Prius, and she parks in the same lot as I do. I plan to run a series of tests, comparing the interior temperature in her car with those in mine (no SR).

When I get back into my car after it is in the sun, I open all the windows for the first few blocks, if I can. Then I close them and let the AC do its job. I think that after a few blocks, the interior temperature will have lowered considerably. It will be interesting to check this as well.

I have a datalogging heat monitor that I will set up in the cars, and access to several Priuses that will park in the same lot. I am working on the protocol now, to make it easier to use the meter. This will take a while to set up, but once I collect some data, I will share it.

Wow!! Can't wait to see the results!

[DaveinOlyWA]

i posted that the fans dont run all the time. even in full sun, mine will still cycle but at much higher duty %.

i tracked mine one day around 9 PM. still sun out, but at a very low angle. on time was about 20-30%. if you are seeing significantly less than this with decent sunlight, i would have it checked, clean the solar panel. a coating of dust will reduce the amount of energy absorbed.

i was sitting out in my car earlier today at work. the fan was doing pretty much as you stated. comes on for 5-10 seconds (sometimes less) and at very low speed. but it was also 60º out with less than spectacular sun.

[Salsawonder]

It has been hot here in SoCal and I love the SR!! It is so wonderful to get into the car and not get the blast furnace in your face. Plus I love driving with it open anytime of day but especially at night!

[Tideland Prius]

Originally Posted by MataOrtiz

Didn't know it got that hot in Canada...

lol. The prairies is much like the midwest. We get low-mid 30s, dry heat (unless there's a moisture feed from the Gulf of Mexico.. then we get the big supercells and tornadoes). Heck, even southern Ontario can get pretty hot. Last year, it was the mid 30s with the humidex in the low 40s (again, thanks to the Gulf for all the moisture)

[PriusRos]

Finally I caught it working as I expected. Strange thing is, it wasn't that sunny today, and was quite overcast when I returned to the car and found the fans running. It was on for at least a minute...I waited for it to turn off but eventually got hot and tired of waiting.

[oviraptor]

If Toyota had done their math right, they have have seen that the most efficient way to cool the car down is by extraction of the hot air, not bringing air into the car. There is not enough venting allowed for in the bodywork to get the air out, so it builds up and actually causes a small positive pressure buildup in the car which actually increases the heat.

There is a new product coming out next year (March 2010) called Cool Breeze. It works by extracting 300 CFM of hot air out of the roof of the vehicle, and uses solar power. It will work in lower light than the Toyota version because the solar panel produces twice the power that the fans (yes multiple fans) need, and they are almost completely silent. There is also a 570 CFM system for larger vehicles.

However any system that works by moving air will only get the interior to the ambient air temp around the vehicle, and humidity is still a problem.

Cool Breeze will cost around $400.00 + fitting, and will fit multiple car types including the Prius, including other Toyota cars, and it will fit in just like a pop up sunroof.

Originally Posted by bearpaw

Greetings - I would love feedback on whether the solar roof cooling system really works. Does it efficiently lower the interior temperature? Is it true that it will only work in direct sunlight or can you park under the shade of a tree and still have it function. Finally, how well does the system work in humid climates? If you have temperature readings, especially those of you in humid climates, could you post them? Thanks.

BTW - an earlier post (below) suggested that you had to crack the windows to boost the efficiency...! The other tips in the list make perfect sense, but I live in an area that receives frequent rain showers so leaving the windows opened is simply not an option.


"1. GET A HEATSHIELD!
2. Crack all the windows about an inch or so.
3. Use the SR in conjunction with the remote a/c, which is how it is designed to be used.
4. Ambient means "close" and that's exactly what happens. Don't expect the same int/ext temp. It's not going to happen."

[Tideland Prius]

Originally Posted by oviraptor

If Toyota had done their math right, they have have seen that the most efficient way to cool the car down is by extraction of the hot air, not bringing air into the car. There is not enough venting allowed for in the bodywork to get the air out, so it builds up and actually causes a small positive pressure buildup in the car which actually increases the heat.

There is a new product coming out next year (March 2010) called Cool Breeze. It works by extracting 300 CFM of hot air out of the roof of the vehicle, and uses solar power. It will work in lower light than the Toyota version because the solar panel produces twice the power that the fans (yes multiple fans) need, and they are almost completely silent. There is also a 570 CFM system for larger vehicles.

However any system that works by moving air will only get the interior to the ambient air temp around the vehicle, and humidity is still a problem.

Cool Breeze will cost around $400.00 + fitting, and will fit multiple car types including the Prius, including other Toyota cars, and it will fit in just like a pop up sunroof.

So you're telling me that if I have the car on (i.e READY and running) and I have the fan (no A/C) running, I'm gonna increase the heat in the car?