Sorry to disappoint you folks. Greath thinking about the A/C and all, but....

....after running my 2004 Prius' A/C for only 5 to 8 minutes (depending on temperature setting and outside thermometer), my battery display can go from 6 bars down to two, thereby requiring the ICE to kick on and recharge the hybrid battery.

And that's if I'm just standing still waiting at a train crossing or a drive-through. If it requires some 28% of my 76 horsepower ICE's effort and a minute or two to recharge my battery from 2 bars to 3 bars, then I'm afraid that maybe the power consumption needs of the A/C are too great for a solar panel's expected output.

My apologies for not being able to put this all into numbers...but I'm neither an engineer nor a mathmagician. Maybe one of you can help me put my perception into a form worthy of a technical answer.

BIF,
75 watts can more than run a car sized A/C unit. The roof area of a Prius is more than enough to give space for 75 watts worth of solar panels.
Cheers,
Steven

Hidden Views Photography

I would pay extra for one of these on a car if it only adds $1500 to the final cost, and pays for itself in 5 years....

http://www.newswise.com/articles/view/512049/

I have seen estimates of A/C decreasing mpg by ~ 20%. If you use 10 kW as an average power use, the AC requires around 2 kW.

So a 75 watt solar panel (assuming that is the net power that goes to our storage battery ??) will provide 1 minute of AC for every 26 minutes in the sun. This is probably a best case example ..

There are other options that don't involve solar panels, like the new flexible solar films that some nanotechnology companies are now starting to sell... they are less efficient but A LOT cheaper, and can be placed onto any surface without affecting its aerodynamics: http://www.nanosolar.com/

In Spain we've got LOTS of sun. When I go to work I could leave my car parked under the sun for 10-12 hours and then have enough AC to get home. Besides, the solar panel would also contribute passively to reduce the heat inside the car.

David.

Hi All:

___The FE hit when running A/C in a Prius I or Insight is > 30% when lab tested. A Hypermiler can easily lose > 40 % in the smaller ICE’ed hybrids! The Prius II is probably similar given it is the same block as that of the Prius I and ~ the same HP although the electric A/C should be somewhat more efficient then a belt driven one … possibly? See below.

___75 W wouldn’t run an A/C unit for a car unfortunately. You might be able to assist the pack to lower its SoC loss from the electric A/C unit over time but even if the car were completely covered with 20 - 22% efficient PV cells, it wouldn’t come close to the power of running the Prius II’s or any other electric A/C that I know of.

___I looked up some of the latest PV Racing automobiles and the top teams have barely 1,500 W on tap using the best cells made in maximum sunlight and with an area of coverage > 8 sq. meters.

Aurora Solar Car

___The typical automobile A/C compressor uses ~ 4000 Watts. Future Truck
___Let us say the Prius II with an electric A/C unit requires just ½ this much because of the electrical compressors ability to run at a much more efficient RPM vs. a belt driven std. mechanical unit which is all over the map. This is still 2,000 W. Even a perfectly flat topped Prius coated with the most expensive Gallium Arsenide PV Cells in existence, the sun directly overhead, and in a southern latitude would probably only be able to generate maybe 750 W at maximum? You wouldn’t have any windows to look out of either … Well, maybe a peephole In the real world using off the shelf and much less expensive PV cells covering the entire roof and hood? You are possibly down to just 150 - 200 W in maximum sunlight.

___Hopefully someone with a much better understanding of PV’s capabilities and of the Prius II’s actual electrical powered compressor needs will reply. I am just throwing numbers out as I find them and I am probably off by a significant margin.

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

Yeah, I've bought solar panels and truthfully they aren't quite up to par with our demands on electricity. You need a lot of space to generate a decent amount of power, and cars use an incredible amount of power, AC is no exception. Think about any refrigeration system and it's power requirements and you'll understand why there's a lot of energy being used to cool your car.

On that note the Air Cars expel clean, cold air as exhaust and in the engine the air is expanded in the first cylinder, then passed through a heat exchange coil to warm up (and cool the air going through the HE) then pass into the next cylinder to be expanded... So as the engine operates it generates waste cool air from the heat exchangers that is ready to be used in the cabin at any time. There is also waste heat generated in the engine from friction and it can be extracted into the cabin as well, so both heating and cooling is accomplished without additional equipment or loss of energy. The cooling effect comes from the expansion of compressed gasses, the compressed air being the fuel cools down when it does it's work in a cylinder, so it can be heated up to it's previous temperature (increasing it's pressure) and injected into another cylinder where it expands and cools and it's done all over again, then finally it exists the engine as cool air exhaust. When air is being compressed there is heat generated, this heat balances with the cooling that happens upon expansion.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings