Solar vent cutoff temp?

Went for a quick test drive yesterday while my civic is in the shop. The 2010 is a definite improvement over the 2009! That said, the dealership experience was a little surreal. Despite having a III w/solar unclaimed on the lot, they were strongly encouraging me to get a II. In addition to making fun of the nav system and pointing out that the upgrade DVDs cost as much as buying a new nav unit once a year, they cautioned me strongly about the solar vent system. They claim the solar ventilation system shuts off if the car interior gets above about 105F, which is no good in Phoenix, where the ambient temp will see 115+ in the summer. This seems odd to me-- can anybody confirm this, or is the dealership working on bad information (or a possibly defective demo car)?

Had my solar vent on and car was in full sunlight. Outside temp - 84°, inside temp after a couple of hours - 111°. I really haven't seen any strong evidence that the system is working as intended.

I could be doing something wrong, but your post suggests that the interior temp was too high for the system to work. All this makes no sense since the entire purpose of the solar vent is to keep the interior from ever reaching excessive temps in the first place.

According to the Toyota website, you must turn on the solar ventilation system before you leave your car every time. I would really like someone to really try this out because if the solar vent does not work then there is no point in me sacrificing the features of a V for a IV with solar.

Is the button able to be left in the "on" position permanently?
Or is it the kind of button that MUST be activated every time you leave the car?

I dont know, I dont own yet. All my knowledge comes from research..

I'm doing a little investigative research myself here...
If anyone knows the answer, please chime in!
I'm just wondering if I should look forward to the slight
inconvenience of having to hit a button whenever I leave my car
parked out in the sun.

You don't have to press the button each time. I leave my switch on and the Solar runs every time.

I would have assumed that it doesn't need to be activated each time you leave the car. The only visual evidence that the system is "on" is the button is slightly depressed compared to the other nearby buttons. Otherwise, there is no way to tell that it is active.

I have tried MANY times to activate it by pressing in the button while the car is in READY mode before turning it off. When that didn't seem to work I also tried it in the ON mode. No difference.

Is it time to call the dealer?

One thing to remember is that the Solar fan does not start for 10 minutes after you power off. That is so that it doesn't exhaust any cool air that may have been inside due to the A/C which may have been on. You should be able to open the door after 10 minutes and feel the air coming from the vents. Hope this helps.

I too live in the Phoenix area and was told by a dealer (Peoria?) that the system doesn't work above 105. I contacted Toyota corp and they responded:

"The Solar Roof package on the 2010 Prius will run any time the temperature is above 60°F and the vehicle is in the sun. At night the system will shut down once the solar system runs out of power. The next time the vehicle is in the sun, the solar system will again begin to function."

I ended up buying a package 3 ( not from that dealer) with Solar and the system operates as described as long as the button described in other emails is depressed. It does help cool the interior but not quite ambient when the sun is searing down at 108 degrees. I'm probably going to get the windows tinted to reduce the heat transmission. The remote start on the AC also helps but usually your not in a position to activate it three minutes before you arrive at the car. Every little bit helps though.

I probably wouldn't have bought the solar vent as a stand alone option but I wanted the nav and moon roof and the vent came along. Now that I have it its a nice toy to have.

This is basically right, except that the lower temp threshold is ABOUT 68 degrees F. The system doesn't actually measure the temperature - but if the temp falls below this number the solar roof voltage my drop too far, shutting down the system. Think of it as a rule of thumb.

There is no upper threshold to the operating condition of the solar roof - it should operate fine in hot desert conditions. (Just don't take it into an industrial oven or something!) If you think it's not, take it to a dealer.

Doug Coleman
Prius Product Manager
Toyota Motor Sales, USA

The low temperature cutoff works just fine. But maybe the Prius Team can let us know if the outside temperature sensor or the inside temperature sensor is the mechnaism for the cutoff. The panel itself could heat up to well into the 90's when it's in the 40's outside, so the panel itself is not the mechanism for cutoff. According to the wiring diagram it's one of the sensors, but I can't decipher which one.

Wayne

This doesn't make any sense. Why would temperature falling below a certain number ("about" room temperature) cause the solar panel voltage to drop? Photovoltaic cell voltage actually should increase slightly as temperature drops. If they didn't work in cold temperatures, our solar-powered rovers on Mars would have major problems. [Although they are of different chemistry, they respond similarly to temperature effects.]

If the INTERIOR temperature falls below a certain threshold, causing the fan to shut off, then it's due to an actual temperature-sensitive switch.

What WILL shut down the solar cooling is a lowering of light intensity below some threshold, whether it's due to the sun being low in the sky, or clouds or shade. It would be interesting to learn what these exact threshold are (angle of sun, degree of cloud cover, etc). We may find out that the panels generate sufficient voltage even in the shade. They will generate some voltage in the shade (or even cloud cover) during daylight, the question is will it be enough to power the fan?

I'm guessing it's the INTERIOR temperature sensor. It makes more sense. If it was controlled by an exterior temperature sensor, then the system would not work in many situation that we would desire, such as a 75-degree, 100% sunny day in San Diego in June, which could easily result in interior temperature of 100 degrees or more.

Carz89 if it is cold enough outside there is no doubt not enough solar energy coming to the panel to make the system run.

Perhaps very generally speaking, but certainly not always. There are many mild-climate places (like San Diego), and paved roads at high elevations (Trail Ridge Road, Colorado) where the daytime outside temperature might be 50 degrees with the sun high in a cloudless sky. Is that "cold enough" to preclude the ability for the solar panels to generate enough voltage? Under such "cold" conditions, the car's interior can still reach 90 or 100 degrees. Many unfortunate children and pets have died inside a locked car because the parent subconsciously thought that it was too cool outside to worry about interior heating.

Answer lock the parents in there let the full extent of darwinism take hold