Solar panel on car - no brainer guys!

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mievsolar

Active member
Joined
May 9, 2012
Messages
32
Why use the AC and Heating from the main battery pack?

Add two things:

1. A larger accessory battery (the existing one is ONLY about 34 AH? or 408 Watts)
2. A solar panel that covers the whole roof.

By adding a larger accessory battery and run the AC and heater off that battery bank you would NOT compromise on the car range at all. Why should you compromise in the first place? People will use less AC and heat less when they know that they have to choose between range and comfort?

Why have to do that at all? WIth an added solar panel and a larger accessory battery they may be no need to run those systems off the main battery pack that will shorten your driving range.
 
Do the math: a panel the size of the cartop would provide maybe a tenth the amount of power that is needed for heating/aircon. For now, about all a rooftop PV panel could be used for is to add a really tiny amount of energy to the battery pack or run a fan or power some other low-power device. Certainly an expensive proposition, not in keeping with our budget-conscious little car.

Given the choice, I'd rather use the deadweight of a battery pack for locomotion instead of personal comfort. The nice thing about the present setup is that I AM given a choice and can be comfortable for the short trips the iMiEV is designed for.

Not a no-brainer.
 
The iMiev also lets you preheat/cool the car as long as it is plugged in, so sometimes this issues is taken care of. Just too heavy, too little power and too expensive for such a car...and probably any car for the near future.
 
The only vehicle-integrated solar that I've seen which comes close to costing out both in terms of money and energy balance is the Solar Electric Prius. http://www.solarelectricalvehicles.com/
When last I corresponded with them, the product had not been a commercial success due to the high development costs of building a quality panel that matched the Prius roof curves, and they had no plans for offering one on the newer Prii or Leaf, i-MiEV, etc.. :cry:
 
Things change quickly in the PV world. I predict that ALL future EV's will have PV roofs.

In fact I just saw a newsfeed where a car running on 100% solar ROOF panel on the car is going around the world. It creates 825 watts and the car can reach a top speed of 60 MPH.

So that car puts EVERY EV to shame. The solar panels is on the roof and looks like the PV array has no problem with the roof curve.

I have contacted company's that makes customer PV thin film arrays but it seems like they really do not want to sell there product as I have not got any return calls...So I will have to try something else. I also want to be able to take the AC and heating off the main battery pack and stick them on a large accessory battery pack and changer the accessary battery pack with solar, but when you plug the charger in it will top off the accessary battery like it doe s now. I can't see that as being to technically difficult, but the difficulty will be getting the wiring diagram and technical help I need.
 
mievsolar said:
Why use the AC and Heating from the main battery pack?

Add two things:

1. A larger accessory battery (the existing one is ONLY about 34 AH? or 408 Watts)
2. A solar panel that covers the whole roof.

With an added solar panel and a larger accessory battery they may be no need to run those systems off the main battery pack that will shorten your driving range.
I found the car for you! - Justin Bieber drives a Fisker Karma and it has a complete solar roof. It also has a 20Kw battery pack (which gives it a measly 32 mile all electric range) and it weighs 5300 pounds

Some details on the solar roof - "The Karma includes as standard a solar paneled roof manufactured by Asola Advanced and Automotive Solar Systems GmbH, a Quantum Technologies affiliate, not only to aid in the recharging of its lithium-ion batteries but also to aid the cabin climate control system. The solar roof is capable of generating a half kilowatt-hour a day and is estimated to provide up to 4 to 5 miles (6.4–8.0 km) of additional range a week assuming continuously sunny days"

We can only guess how many thousands this roof added to the cost of the car (it's a $115K car) but if left sitting in full sun for an entire week, it gives you 4 to 5 extra miles of range - VERY expensive miles as it turns out

Don
 
Don said:
We can only guess how many thousands this roof added to the cost of the car (it's a $115K car) but if left sitting in full sun for an entire week, it gives you 4 to 5 extra miles of range - VERY expensive miles as it turns out
A little more research turns up the actual cost. "There is additional value added in design and equipment improvements such as the now-standard integrated solar roof panel, which would have been a $5000 option"

It 'theoretically' can add 4 to 5 miles per week in range, but in actuality, the power generated is mostly used to cool the inside of the car when it's parked out in the sun, so there is little actual battery power gain over a car which doesn't have a solar roof, but is kept out of the sun

Certainly a good looking option (what could look neater on a battery powered car than a roof made up completely of solar panels?) and no doubt functional (after a lunch stop it would be nice to come back to a car which isn't so hot inside) but for $5,000 one has to wonder if the cost is anywhere near worth the benefit? Even if Mitsu could somehow manage to pull off a solar roof for half the $5K cost, I think the extra $2500 would detract from car sales . . . . especially once people saw how little return they were getting for all that money - It would have to be an option, for sure

Don
 
MUCH better to put a 3-6kW PV system on the roof of your house! Several companies are now offering lease deals with $0 down -- you will pay about half as much as you do now for electricity, and you get to drive "for free".
 
I would not dismiss the idea.
It may seem cost prohibitive at present time and when looking at Fisker Karma cost of solar roof ($5000 as per above by Don) and MPGe=52.
However, technology is improving. I have made my calculation based on:
1) pricing of 15.7 sq. feet PV panels at $295 for 205W:
http://www.solarsystemsusa.net/solar-panels/panels/vikram/elv-205/
2) area of iMiEV roof = 20 sq. feet
3) solar day = 8 hours
This gives 2.09 kWh per day for $375 (PV only), which in my hands provides 10 miles of range per day, which in turn covers exactly my daily RT commute. So, if we manage to mount PV on the roof at reasonable cost, low weight and hook it up to the battery, this would provide very appealing claim.
 
jaraczs, nice to see you doing the math, although I would also include all the intermediate hardware and its inefficiencies, not forgetting to include the negative effect on the iMiEV's already challenged Cd. I, for one, would not like to raise the iMiEV's CG either.

You might note that we already have an extensive thread on this topic and you might wish to peruse it. For a photo of what someone had done (not to an iMiEV), have a look at this post on that thread:

http://myimiev.com/forum/viewtopic.php?p=3435#p3435

Yes, of course it is possible to add solar to an iMiEV. What would you define as "reasonable" cost and effort to achieve what end result?

Maybe you and PV1 should collaborate?
 
jaraczs said:
However, technology is improving. I have made my calculation based on:
1) pricing of 15.7 sq. feet PV panels at $295 for 205W:
http://www.solarsystemsusa.net/solar-panels/panels/vikram/elv-205/
2) area of iMiEV roof = 20 sq. feet
3) solar day = 8 hours
This gives 2.09 kWh per day for $375 (PV only), which in my hands provides 10 miles of range per day, which in turn covers exactly my daily RT commute. So, if we manage to mount PV on the roof at reasonable cost, low weight and hook it up to the battery, this would provide very appealing claim.
First, if your vehicle can make the daily round trip you need it to, why put panels on the car? On the car you cannot aim them and they'll be giving you maybe 1/3rd of what they would if they were on a fixed structure, properly aimed at the sun

It's difficult to come up with actual numbers when you're talking solar - You surely cannot do it by multiplying the panel's theoretical best output times the number of hours you're going to set it in the sun. For one, panel manufacturers all quote best possible case scenarios when giving you the panel output. Clear, cloudless day, panel oriented so the sunlight strikes it at a 90 degree, perpendicular angle and the panel well ventilated so it generates minimal heat

On a building, you orient the panels at an angle which is a compromise of a best case average over the angle of the sun at your particular latitude for all 4 seasons of the year - Sometimes you fudge it a little toward the winter angles because the panel does pretty well in full summer sun being off angle a bit and since it's already compromised by the lower winter angle, you try to improve the winter efficiency by giving up just a little summer efficiency. At any rate, for that half hour when the sun is exactly where you want it to be, the panel actually comes pretty darned close to what the manufacturers spec says it will, but that's the only time - The average over an 8 hour day might be only 50 or 60% of the advertised output. Most operators of fixed panels properly aimed use some number around 60% of maximum in their calculations for a day's total output . . . . even if they don't calculate it that way, that's closer to what they'll actually get

Mount the panel flat on a vehicle roof where you cannot set it for your latitude and your output goes way down, which is why your theoretical outputs look so much better than those reported for the Fisker Karma - They are giving you actual, real world numbers and you're comparing them to pie in the sky numbers you're never going to come close to getting. When we use panels on sailboats, we can aim them a bit for better output . . . . nothing nearly as good as fixed panels on your garage roof, but we can get much better numbers than you're ever going to see with the panels flat on your car's roof. If you lived where I do, the gain you'd see from leaving your car sit in the sun charging all day would be almost entirely offset by what the A/C is going to use cooling the car off when I get into it to drive . . . . I'm about as well off by leaving the car parked in the shade. I'd be much better off leaving it parked in shade provided by 150 to 200 sq ft of solar panels and then I don't need to mount them on the car :mrgreen:

So, when running the numbers for use on a car, I would plan on getting about 1/3rd of what you're currently thinking and then decide if the modification costs are worth the gains - Not to discouragfe you from going forward . . . . I love it when anyone does these sorts of mods and then has the capability to generate real world numbers as it helps everybody who follows in their footsteps. The very idea of a vehicle which can drive even partly powered by the sun is EXOTIC and it's certainly worth pursuing . . . . but I wouldn't go into it expecting to get anywhere near 8 times the theoretical maximum instant output of the numbers printed on the panel

Don
 
I thought about this for my converted car. The collecting area would only manage about 300W. I would be better off with more solar on the roof at home always at the right angle and more battery in the car.
However, the one thing that would be useful in hot, sunny areas would be some PV to run a fan just to keep the car ventilated while locked up and parked in the sun. It would automatically do more when the car is in the sun and do less or nothing when in the shade. If the car is cooler when you return to it the saving comes from not using the air con from the main battery as much.
 
JoeS said:
PeterC, congrats on getting your iMiEV soon. Agree that a small solar-powered fan to ventilate the car's interior would be nice (Leaf and Prius have those as options). In the meantime, I found this windshield cover, mounted externally, worked wonders this summer: http://myimiev.com/forum/viewtopic.php?p=10258#p10258. BTW, where in Australia are you?
I am in Canberra. The advantage about the ventilation idea is that no effort would be required, but, yes, a windshield cover is on my shopping list as soon as I collect the car. I agree they make a big difference.
 
mievsolar said:
Why use the AC and Heating from the main battery pack?

Add two things:

1. A larger accessory battery (the existing one is ONLY about 34 AH? or 408 Watts)
2. A solar panel that covers the whole roof.

By adding a larger accessory battery and run the AC and heater off that battery bank you would NOT compromise on the car range at all. Why should you compromise in the first place? People will use less AC and heat less when they know that they have to choose between range and comfort?

Why have to do that at all? WIth an added home solar panel and a larger accessory battery they may be no need to run those systems off the main battery pack that will shorten your driving range.
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