Questions for all you solar roofers

I don't have a Prius yet, but last year when I first was told what little the solar roof does, I guffawed and was dead-set against it.

Now however I am seeking a Prius with the solar roof option.

For one, the air to cool the traction battery for the Prius is pulled from the passenger cabin. So cooling that air may help prolong battery life. (This is my thought on it--I haven't done any research yet to substantiate it.)

Secondly, even if your ambient temperature only gets to 68 degrees, the temperatures inside the cabin on a sunny day are going to be significantly higher.

Third, I don't know that the solar roof really adds significant weight to the car. What little it adds is probably offset by the benefits of using the AC less and battery life.

But I also wanted several of the features that come bundled with the solar roof, like the premium NAV.

In any case, I no longer view the solar roof option as being useless.

Regarding the dogs, keep in mind that the fan does not run continuously while you are out of the car. It is only set up to run when you are near to the car and turn it on. The maximum range is about 30 yards. NOTE: Another Priuschatter corrected me on this point in a later reply. It does run continuously, apparently. The car salesman told me wrong!

 

I was at the NY auto show recently, and saw a high performance EV car. For the life of me, I cannot remember the name, but it was a Tesla like vehicle, and all their models had solar panels on the roof. The company claimed that they would provide UP TO 200 extra miles annually. Probably out in the Arizona desert with full sun.

 

That's actually the 'remote AC' operation being described - the ability to turn the AC on before you get to the car.

The main benefit of the solar panels is the ability to power a ventilation fan all the time the car is parked in sunlight bright enough to generate enough electricity. There is a switch you can turn that feature on and off with, I usually leave it on only in the late spring/summer months when it's hot enough to want the ventilation to run to exhaust the hot air that would build up. When it's 90 or 100 degrees it helps a lot!

The main benefit to me of the sunroof is the availability of opening the roof on spring/fall days and enjoying the fresh air, and of being able to have more light in the cabin all the time.

 

The concept behind the vent system is to keep the interior cooler so you don't have to run the AC as much. An added benefit to having the sunroof is that you can leave the shade open in the winter and let the sun warm the interior a bit.

It would have been nice if Toyota had engineered that solar panel so that it was always working when the sun shines. That's free energy, and even if it's just a drop, it would help. I just don't understand why the solar system isn't linked to the main battery.

I agree that the price of the sunroof is a bit steep, and I don't understand why it's bundled with the Nav option. Oh well, I got it anyway.

It doesn't effect mileage in any substantial way, if at all. If you drive with it open, of course it's going to change your aerodynamics. But I wouldn't worry about the weight.

Of course, the best option for leaving your dogs in the car would be to crack the windows AND open the sunroof. I wouldnt rely on the vent system to keep the interior temp the same as outside.

 

Does the sunroof actually tilt open when the solar fan is running? If it does, could someone post a photo?

If it doesn't open, where does the fresh air enter the cabin? A/C vents?

Thanks

 

the air enters the cabin from the vents. The sunroof will not move unless you open it. Think of the sunroof & the solar vent as two seperate systems.

 

You can opt to have the roof tilted open, and it probably makes it more effective (though the car will give you a warning tone when you're getting out). I leave the switch turned on all the time. Why not?
I ended up waiting in the car the other day while my wife ran in for some groceries. The sun was bright (close to noon) and the outside temperature was 57 degrees. I had the windows open as well, but the fan came on from time to time with a good flow of air. I was impressed. It made it more comfortable to sit in the car. The roof was kind of dirt from driving in the rain a few days earlier but the fan ran strongly.

Actually one advantage of the sunroof package is it means that 80%+ of your roof surface is glass, which is more toerant of bird droppings, etc.

 

We are moonroof buyers whenever possible and I like the gadget factor on the the Prius solar addition. I'm surprised how efficient the system is, it doesn't have to be a 90 degree day for system to work. I still get a grin when imhearnthe fan blowing upon entering. We live in San Diego and my wife uses the remote A/C at work when going to lunch and leaving for the day as temps can get high 90's inland in the summer.

Resale is another bonus. When you do sell the car it helps your car stand out a bit from the others.

 

Oh!

Do you mean to say that the sales rep explained it to me incorrectly last year?!?? What a shocker.

If he'd told me that it was on all the time that the car was parked in the sunlight, I wouldn't have every formed the opinion that it was a stupid idea. I couldn't for the life of me figure out why Toyota would only allow the fan to run for the minute or so that it took me to walk across a parking lot to my car. I've been carrying around incorrect information for over a year!

 

+1 ~ Love the solar pkg. Wish it did more but does keep the interior nice & fresh. Looks great, too. No regrets!

 

Actually, the effectiveness of the solar panel has nothing to do directly with temperature. Solar panels actually *reduce* slightly in efficiency at higher heat.

It has to do with the amount of direct (and partly indirect) sunlight striking the panel. The insolation value of the sunlight in your location (watts per meter squared) is how you figure your amount of available sunlight. It varies depending on the location and time of year (and of course whether it's sunny that day).

But don't think that the insolation value is going to be the amount of power that you'll get out of a solar panel. That's just the amount of sunlight energy that strikes one square meter, on average. Solar panels are only about 15% efficient at turning that light into electricity, so to get a reasonable figure you would multiply by 0.15.

 

The panel is rated 22v 3.6a in full sunlight. That is plenty to run into a battery charge controller to charge a 14v SLA or other smaller batteries. It should be enough to run into an inverter to make HV for charging the HV battery bank. Someone needs to try that.

My use of my solar roof will be for the ventilation system and switched to a battery charge controller to charge my batteries that run my low power Amateur Radio equipment when I am out in the parks operating.

Mike

 

Answering another of the OP's question: the solar roof will slightly reduce mileage, due to increased weight and slightly worse aerodynamics.

However, and this is a big however, note the word "slightly" - in practice I don't think anyone will notice the difference.

Tom

 

Am I right that you have to be pretty close to the car for the remote A/C to come on? In that case it can't have much effect on the temperature in the cabin, can it?

 

The roof panel isn't near big enough to charge the HV.
I'm doing the math to set up a solar charging system for my PiP.

To charge the battery fully in 6 hours of sun, you'd need approx 5ft x 20ft of solar panels.


I was hoping for that too and spent months learning solar math to see if it was possible. FYI, the base setup for batteries plus panels to do it (at home, charging batteries during the day, charging the PiP at nite) is about $6k.


*i'm not an expert, just starting to get this larger scale stuff figured out.

 

I guess the factory panel is only destined to charge smaller batteries for the Amateur Radio guys use The car would look silly with it's complete top side covered in solar panels for a HV charging system. Thanks for checking up on this.

Mike :tea: