JoeS
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Re: solar on the car roof

Wed Aug 15, 2012 4:01 pm

PV1, I admire your tenacity pursuing this subject, even though the math perhaps by now should have shown you the negligible benefits relative to the cost and effort; nevertheless, I thought you might enjoy the following two photos of a solar-assisted Solectria Force which were posted a few days ago on our local Electric Auto Association mail list. No information available about this contraption. BTW, I assume you're planning on solar-->regulator-->?Vbattery-->inverter-->EVSE-->J1772, or were you thinking of adapting to CHAdeMO? So, what's the latest with having a simple 120vac outlet at work and save yourself lots of time and $$$? When are you going to get an iMiEV?

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EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
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iMiEVNZ7
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Re: solar on the car roof

Wed Aug 15, 2012 4:15 pm

Grin JoeS,
The solution would give good power but is a bit wind prone for the iMiEV ! I think PV1's idea of the thin film ones is best, and we plan to do the same too. I think, even if it turns out to be no good for recharging the main battery it would be easily useful for running a fan to cool the car during hot days, where no shelter is possible like in a large carpark, and for recharging a 2 Kw get me home battery pack to recharge via an inverter to EVSE to the main battery.

Update on our purchase.. still waiting for approval from the boss, we have one month hire sorted, and another client is doing a test drive of a dealer car today, and if all works well, that will give us another month hire, when we get three months hire sorted, we are good to go, if finance works well.

Don
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Re: solar on the car roof

Thu Aug 16, 2012 5:13 am

JoeS wrote: . . . . I thought you might enjoy the following two photos of a solar-assisted Solectria Force which were posted a few days ago on our local Electric Auto Association mail list. No information available about this contraption.
Well, he accomplished three things for sure! 1.) He's got enough panels to make a difference, 2.) He's got them tilted enough so that whenever he parks the car facing south (or north if he lives Down Under) they'll probably give him more than 50% of their rated output, and 3.) His car is in the shade most of the time so he won't be needing nearly so much A/C. On the downside, he's really hurt his top speed and the energy required to drive more than just a few miles per hour has gone up . . . . but now everyone knows he's driving a 'solar car'!!
BTW, I assume you're planning on solar-->regulator-->?Vbattery-->inverter-->EVSE-->J1772
One other BIG plus for his 'contraption' - I'm betting that this car is a homebrew conversion running off 96 volts, and that these are 24 volt panels, so he's charging the traction pack directly rather than using the very inefficient method of charging an intermediate battery and then using an inverter to charge the main battery. For our car we would ideally need teeny-tiny solar cells so that 350 volts worth would fit on the roof - A very small amount of current, but the roof could charge the traction pack directly. I suspect this is how it works on the Fisker Karma, which is probably why it cost them $5K to do

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE, White
2014 Ford Transit Connect XLT SWB wagon, 14,000 miles
1994 Miata 60K miles - Soon to be sold
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jray3
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Re: solar on the car roof

Thu Aug 16, 2012 11:14 am

Sorry Don, as JoeS said, this is a Solectria Force from the mid 90's.
http://en.wikipedia.org/wiki/Solectria_Force
AC drive, but still only 156 volts, easy to charge thru an inverter or perhaps directly from those big panels.
Of course, the array is comical and counterproductive.
2012 i-SE "MR BEAN" 76,000 miles
i-ES traded at 21,648 miles
2000 Honda Odyssey
1987 F250 Diesel
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Don
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Re: solar on the car roof

Thu Aug 16, 2012 11:33 am

Well shoot - But as I said earlier, empherical evidence beats all kinds of theoretical guesses :oops: ;) :D

I suppose he could still charge the traction pack directly with some sort of automatic switching relay - Charge 1/2 of the pack for 10 or 15 minutes, connect to the other half for 10 or 15 and repeat . . . . endlessly. That wouldn't be terribly hard to rig up - Still beats charging an intermediate battery and all the associated losses that brings

Comical for sure and maybe not terribly productive but I'll bet he feels just like PV-1 . . . . at least he's doing something even if it isn't terribly practical

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE, White
2014 Ford Transit Connect XLT SWB wagon, 14,000 miles
1994 Miata 60K miles - Soon to be sold
1979 Honda CBX six into six

JoeS
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Re: solar on the car roof

Sun Aug 19, 2012 12:26 pm

This solar-powered Solectria Force might be a contraption, but let's see just how practical it might be. Simply eyeballing them, say those panels combined produce 600W peak (dunno what these are, but I would use the highly-efficient SunPower panels in this application). So, let's say if they're properly pointed into the sun they're averaging 400W output over a sunny nine-hour workday (preumably he/she goes out at lunchtime and moves it). That's 3.6kWhr. Say there's a dc-dc converter with a wide input voltage range that feeds the 156V battery pack directly and let's assume a 85% converter efficiency, which means he/she feeds 3kWh into the traction pack during the workday.

If it was feeding my iMiEV which has a lifetime history of 4.2miles/kWh then I'd be getting 12.6 miles daily off these panels. Unfortunately, my iMiEV would no longer be getting 4.2mils/kWhr with all this stuff plastered on it, so that's yet another issue. This whole discussion is aimed at the commuter who has a 40-mile one-way commute in the iMiEV and cannot recharge at work. This additional 12.6-mile range increase would still not solve the problem, even if the iMiEV's efficiency was unaffected. For that scenario, I would think you'd need to add at least 20 miles additional range if this is going to be a serious commuting solution. Say, nicely-contoured flexible solar panels are employed, their relative inefficiency and surface area still wouldn't solve the problem, IMO. In any case, a cloudy/rainy day would mean you sleep at work that night. :roll:

If it was me, I would try really hard to find a place to simply plug into 120vac while at work. How about working out a deal and parking in back of a nearby gas station? :lol:
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

iMiEVNZ7
Posts: 122
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Re: solar on the car roof

Sun Aug 19, 2012 1:29 pm

Hi JoeS,
Maybe one could carry an extra battery pack in the car boot and use solar too. For the same weight as 2 back seat passengers, assuming 85 Kg people, for a total of 170 Kg, one could have a 40 Kg inverter, and at 30 Kg per battery, say 4 Batteries.

That would give approx 4 Kw extra, and with say another 1. 7 Kw per day from the solar panels, a extra if needed, range of
5. 7 Kw or say 5 Kw , and @ 160 watts/ hr per Km, that would give another 31 km.

So say a round trip to work is 100 Kms, using most or all of the 16 Kw main battery and with no at work charging available, with the 300 watts of thin film solar providing say, 200 watts over the 8 hours, it would give a buffer of 31 Km if a unplanned trip was needed on the way to work or on the way home.

A timer or circuit could be used to prevent too deep a discharge on the extra battery pack on days the extra range was not all needed if one knew ahead of time.

For our longer trips, we are.. cough, taking two honda or similar, 2000i petrol generators to recharge via a 3.3 Kw EVSE.

The cost of the petrol for the generators, even for a full charge is less than running our petrol car for the same distance. $ 15 compared to $ 24.

Don
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Re: solar on the car roof

Sun Aug 19, 2012 6:03 pm

iMiEVNZ7 wrote:So say a round trip to work is 100 Kms, using most or all of the 16 Kw main battery and with no at work charging available, with the 300 watts of thin film solar providing say, 200 watts over the 8 hours, it would give a buffer of 31 Km if a unplanned trip was needed on the way to work or on the way home
You're probably never going to get 66% efficiency from solar panels glued flat on the roof which you can't aim at the sun and then (as Joe mentioned) you're left high and dry on cloudy days - Not a practical solution

Rather than a series of expensive modifications which might work most of the time, if I needed transportation beyond the range the i can provide, I would buy another car. If it's marginal now, think what it will be like in a couple years when our 16 Kw battery is only 80% efficient, or when it's cold out and your 80% battery can only deliver 65%, or when you need heat for that 100 Km drive

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE, White
2014 Ford Transit Connect XLT SWB wagon, 14,000 miles
1994 Miata 60K miles - Soon to be sold
1979 Honda CBX six into six

PV1
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Re: solar on the car roof

Wed Aug 22, 2012 6:54 am

Nice. Hopefully thin films are lower profile, :D . I was thinking of using the panels from eBay. I could fit 6 on the roof, 2 wide and 3 long. Which 50 watt'ers were you talking about?

I might be getting an i next February or March. The setup I was imagining was:
Panels --> MPPT --> 48 volt LiFePO4 battery --> inverter --> EVSE --> J1772.

The battery pack would be made up of 200 ah cells, wired in series for 51.2 volts nominal, giving me 10 kWh of storage, plus a kWh from solar, good for 11 hours on level 1.

Since I'm stuck in the middle of the natural gas boom geographically, having an EV powered by solar that's on the roof would make a statement that would get people thinking outside of fossil fuels.
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
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NeilBlanchard
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Re: solar on the car roof

Wed Aug 22, 2012 9:41 am

Those panels would add a LOT of aerodynamic drag -- probably like 3 or 4 more "car's worth"?

Here's a car that can drive using just the power from the (very high efficiency) PV panels -- they have about 830W output:

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The SolarWorld GT car built by Bochum University is about 800 pounds and it has a Cd of just 0.14. It has extremely efficient motors in the hubs of the front wheels. It can go about 31mph in full sun. It consumes about 35Wh/mile -- compare this to the i MiEV!
Sincerely, Neil

http://neilblanchard.blogspot.com/

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