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### Re: Solar panel on car - no brainer guys!

Posted: Sun Oct 14, 2012 5:44 am
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?

### Re: Solar panel on car - no brainer guys!

Posted: Mon Oct 15, 2012 6:43 am
jaraczs wrote: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-pa ... m/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

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

### Re: Solar panel on car - no brainer guys!

Posted: Wed Nov 06, 2013 4:45 pm
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.

### Re: Solar panel on car - no brainer guys!

Posted: Wed Nov 06, 2013 9:47 pm
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?

### Re: Solar panel on car - no brainer guys!

Posted: Wed Nov 06, 2013 11:27 pm
The best known slovenian expert Andrej Pecjak installed such panel on the roof and tailgate. In optimal conditions cars main battery is solar charged in one week. IMHO it's just to expensive toy for the positive outcome.

### Re: Solar panel on car - no brainer guys!

Posted: Thu Nov 07, 2013 1:36 am
JoeS wrote: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.

### Re: Solar panel on car - no brainer guys!

Posted: Tue Nov 14, 2017 12:06 am
mievsolar wrote:Why use the AC and Heating from the main battery pack?