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Old 31st March 2010, 18:59   #1
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Default Solar AC for cars

Is it possible to get a car AC powered by solar cells? Say, we fix the solar panel on the roof or/and the bonnet and it powers the air conditioner. All that we need to do is to park the car in the sun!

I vaguely remember seeing a photo a couple of years back of such a car in the Khaleej Times, published from the Middle East. Has anyone from the middle east spotted such a car? The featured model was a red car with solar panels on the roof.
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Old 31st March 2010, 19:47   #2
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Originally Posted by lejhoom View Post
Is it possible to get a car AC powered by solar cells? Say, we fix the solar panel on the roof or/and the bonnet and it powers the air conditioner. All that we need to do is to park the car in the sun!

I vaguely remember seeing a photo a couple of years back of such a car in the Khaleej Times, published from the Middle East. Has anyone from the middle east spotted such a car? The featured model was a red car with solar panels on the roof.
It is possible and next gen Prius will have it. Some models of the present gen prius use solar cells to run an exhaust fan to pump out air when parked.

From Wiki:
A Solar Roof Package includes the Navigation Package and adds a power tilt/slide moonroof along with a solar powered ventilation system which uses an electric fan to help keep the vehicle cooler when parked under the sun by venting the interior's heated air with the outdoors. The solar roof was originally intended to assist in charging the vehicle's battery, but the system was configured to only power ventilation when it was found that the battery-charging configuration created electromagnetic interference that affected the radio.[60] A new remote air-conditioning feature allows the driver to activate the air conditioner prior to entering the vehicle.

Last edited by Rehaan : 1st April 2010 at 12:02. Reason: Removing some formatting tags.
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Old 31st March 2010, 20:45   #3
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The current get prius has solar cell run the blowers when the car is parked that this increases AC efficiency. There is no indication that the next gen will have solar AC.

AC needs a good 3-4 kW steady state to run and the roof panels simply cannot handle that.
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Old 31st March 2010, 21:14   #4
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For the size of solar panels that you could fix on a car, it would not be capable of powering a AC.
It might power a fan which I think is what is used in Maybach if I remember correctly. Even for charging the batteries in a hybrid or plug-in type, the power obtained from a solar panel on car might move you for 5-6 kms after charging for 5 or more hours.

Its difficult to beat the energy density in fossil fuels unless you scale up solar panels.
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Old 31st March 2010, 21:41   #5
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Originally Posted by Mpower View Post
AC needs a good 3-4 kW steady state to run and the roof panels simply cannot handle that.
Who told you that AC needs 3-4 kW ? A 1 ton split AC in home consume about 1.3 kW/ Hour and also note that the car battery is capable to hold about 780 watts/hr (as in my Scorpio). Then how can AC take 3-4 kW from battery if the battery is capable to hold only 780~1000 Watts/Hr.

The solar Panels if installed on the roof will give/charge at about 75~150 W/hr. and can easily power Car AC for constant if car is running in Sunlight ,not is shade. So Using a Solar Panels to Power AC or ICE is an good idea. But this may be costly because of high rates of Solar Panels in India because currently India is not manufacturing solar cells. All just being Imported.
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Old 1st April 2010, 15:06   #6
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Not directly related, but since you seem to be interested in Solar power : Linky to thread on using Solar power to charge batteries (Project Nomad: Solar Power for charging batteries!)
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Old 1st April 2010, 16:28   #7
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A typical car AC peaks at over 3 tonnes!
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Old 1st April 2010, 17:14   #8
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A solar panel cannot generate enough electricity to power an Aircon of a car. Besides the cost of a panel that big will almost cost a car and talk of fiting it
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Old 1st April 2010, 17:28   #9
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This is not directly related, but I remember reading somewhere about the panoramic roof of the Maybach having solar cells which helps in keeping the car cool when parked under sun.
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Old 1st April 2010, 17:49   #10
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Quote:
Originally Posted by iamback View Post
Who told you that AC needs 3-4 kW ? A 1 ton split AC in home consume about 1.3 kW/ Hour
Apart from the line above which might be correct in some cases, the rest of your post seems rather incorrect to me ...

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Originally Posted by iamback View Post
and also note that the car battery is capable to hold about 780 watts/hr (as in my Scorpio). Then how can AC take 3-4 kW from battery if the battery is capable to hold only 780~1000 Watts/Hr.
Simply by running less that an hour!

Remember, even a 500w/hr battery can still manage to power a 1000watt device for 1/2 an hour!

Quote:
Originally Posted by iamback View Post
The solar Panels if installed on the roof will give/charge at about 75~150 W/hr. and can easily power Car AC for constant if car is running in Sunlight ,not is shade.

If you're talking without a battery, this is not possible!


If you're making $100 a month its just not possible to pay a $200 EMI.

However, if you have $2000 in your bank account to start off with (ie your battery) you can manage to pay your EMI for more than a year, even with a $100/mo salary.

Quote:
Originally Posted by iamback View Post
So Using a Solar Panels to Power AC or ICE is an good idea. But this may be costly
True. Current technology needs to improve and become more affordable.

Quote:
Originally Posted by iamback View Post
because of high rates of Solar Panels in India because currently India is not manufacturing solar cells. All just being Imported.
Incorrect!
Eg. Photovoltaic Cell Manufacturers in India

cya
R

@_raVan_ - See shrishiva's post above. As mentioned, the maybach panels power a simple fan, not an A/C. The compressor of the AC is what sucks up the majority of the power.

Last edited by Rehaan : 1st April 2010 at 17:52.
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Old 1st April 2010, 19:42   #11
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Quote:
Originally Posted by iamback View Post
Who told you that AC needs 3-4 kW ? A 1 ton split AC in home consume about 1.3 kW/ Hour and also note that the car battery is capable to hold about 780 watts/hr (as in my Scorpio). Then how can AC take 3-4 kW from battery if the battery is capable to hold only 780~1000 Watts/Hr.

The solar Panels if installed on the roof will give/charge at about 75~150 W/hr. and can easily power Car AC for constant if car is running in Sunlight ,not is shade. So Using a Solar Panels to Power AC or ICE is an good idea. But this may be costly because of high rates of Solar Panels in India because currently India is not manufacturing solar cells. All just being Imported.
A little clarification if I may.

As mentioned in the heading 1 hp is equal to 746 watts.

The condenser fan takes up about 400 watts.
The evaporator fan or also called the blower fan takes up about 250-300 watts on full blow.
The mechanically connected compressor takes up about 3 horsepower which is about 746*3=2238watts via the V belt.
The electro-mechanically operated AC clutch takes up about 80 watts.

The alternator supplies the current when above idling rpm to all the Air Conditioning circuits except for turning of the compressor which no automobile battery/alternator can make it to function. Present day automobile car battery or alternator cannot run the compressor even if it wanted too. Hence the rubber belt to run the compressor. It is actuated by the AC clutch though which is made to function electrically.

Do the maths and figure out how much power the full ac circuit takes up including the running of the compressor. Also note that starting current for any compressor is 3 times the rated wattage which then in our example works out to about 7000 watts.

No solar panel with current technology that can fit on the full surface area of the car can make the compressor run. At most with current solar tech it can make the evaporator fan function and the compressor clutch.
The idea in the Prius and other such cars is to continuously operate the exhaust fan such that the load on the AC is reduced when we switch on the AC. It is similar to bringing down all the windows when the car is parked in the baking sun and the seats dash and steering are being toasted.

When parked in the hot sun the inside temperature of the car will be about 10 degrees more than outside ambient temperature.

Last edited by drpullockaran : 1st April 2010 at 19:46.
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Old 1st April 2010, 19:59   #12
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Quote:
Originally Posted by Rehaan View Post

Remember, even a 500w/hr battery can still manage to power a 1000watt device for 1/2 an hour!
Dear Rehaan, though it does seem logical that a 500watt/hr battery should run a 1000watt load for half an hour it is not so in the real world. Battery manufacturers always hype their actual power output. Its similar to amplifier manufacturers extolling the amp output in pmpo instead of continuous power output. RMS output is the basic minimum amp output should be quoted in.

Please scour the net on internal resistance of lead acid battery's and their actual capacity. If my memory serves me right the actual continuous loading capacity is about one tenth the rated output. I do agree extremely short duration high load can be taken but the internal plates bend on high loading resulting in an internal short making the battery useless.

Battery life in the Indian context is cut short due to extremely heavy loading in bumper to bumper traffic in the night when every single electrically accessory is functioning literally continuously.
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Old 1st April 2010, 20:21   #13
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Quote:
Is it possible to get a car AC powered by solar cells? Say, we fix the solar panel on the roof or/and the bonnet and it powers the air conditioner. All that we need to do is to park the car in the sun!
Huh, Who would prefer to intentionally park their cars in hot sun? Be ready to install good window films first!
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Old 1st April 2010, 21:15   #14
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Quote:
Originally Posted by iamback View Post
Who told you that AC needs 3-4 kW ?
um...I believe he was from Hitachi corp....& who told you that it does'nt?

methinks its not a good idea explaining thermodynamics to 15 yr olds. (Age of Team-BHPians?) Maybe you want to wait until next year when you reach 10th standard, then you might understand

Quote:
Originally Posted by Rehaan View Post
Apart from the line above which might be correct in some cases, the rest of your post seems rather incorrect to me.
other than a Reefer truck, I can't think of any.

Quote:
A typical car AC peaks at over 3 tonnes!
thats 36000 Btus/hr. So with a typical EER of 10 you are looking at 3.6 kW already. Is my math correct prof?

Last edited by Mpower : 1st April 2010 at 21:51.
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Old 1st April 2010, 21:19   #15
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If you had to invest in a solar cell, you are better off putting it on your roof. it will be cheaper, easier to install and maintain, easier to utilize, and safe from elements.

when we have more money, time, inclination and need, we can move on to other stationary targets. Cars should be last.

on a related note, owners are known to install panels on their roof and use it to charge their electric vehicle. that's practical.

EDIT: found this http://en.wikipedia.org/wiki/Solar-charged_vehicle
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