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EVDRIVER
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Re: Solar Solution

Wed Nov 07, 2012 9:48 pm

The answer remains the same, solar is best on land and putting them on the car is a complete waste of time. If in doubt, see how it works out and report back with an honest answer. It is as practical as a fan generator on the front grill.

malkit
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Delivery Date: 31 Dec 2012

Re: Solar Solution

Thu Nov 08, 2012 8:58 am

JeremyW wrote:
malkit wrote:I want to mount 2-250 watt solar panels on my car and charge it while parked 8 hours when i am working in office.
Have you seen solar panels in the 200 watt range up close? They are large. Not something you can mount on a car or move around easily. :)

The panel dimensions are:
Panel Dimensions 64.57" x 39.37" x 1.38"
Leaf dimensions
Length: 4445 mm / 175.0 in.
Width: 1770 mm / 69.7 in

The panel length is less than nissan leaf width, so they will fit without jutting out. I am planning to install 255 watt panels and not 220.

Once i am done with installation i will post photos and videos.

fooljoe
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Re: Solar Solution

Thu Nov 08, 2012 10:24 am

What no one here has addressed yet is how these panels will actually charge the car. Set aside for a second the fact that carrying around panels in the trunk instead of just installing them on your roof at home is terribly impractical...

You have 2 250 watt panels. That means you'll have maybe 350-400 watts of AC power available at a maximum (only for about 1 hour on the sunniest of days in summer). On L1, the charger requires 120v @ 12amps, or about 1400 watts. So how in the world do you expect to charge? I haven't tried this to be sure, but will the EVSE/charger operate at all if at least 12 amps aren't available? For most of the day you'd have barely enough power just to operate the cooling fan.

I suppose it may be possible to skip the inverter and get a DC-DC converter to step up the voltage from the panels to ~400VDC then feed it in (at a truly miniscule current) by splicing directly into the pack's DC lines, but I'm guessing you're not prepared to do this. The other option would be to store up a couple days worth of solar in a bank of 12v batteries, then feed it through your inverter when you get enough power to support L1 for maybe an hour, then repeat. How's your trunk looking now with a few car batteries thrown in with 2 giant panels and an inverter?

So, back to that first fact that we set aside. Just install some panels at home and tie them in with the grid. Switch to time of use metering. Then the panels will produce during peak hours when electricity is most valuable, and every small amount they generate can actually be used by your house or banked as credits. And they'll keep on producing even when you're not at work. Then charge your car in the middle of the night when electricity is cheap. Depending on your utility's rates and the season, you may be able to pull 5x as many kwh in the middle of the night as your solar produces on peak and still break even. Makes wayyyy more sense.
RavCharge.com | 2012 Rav4-EV | 2011 Leaf SL w/QC batt replaced 11/20/15 | Clipper Creek CS-60 | EVSEupgraded 2013 Leaf EVSE | 3.84kw PV

malkit
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Re: Solar Solution

Thu Nov 08, 2012 11:42 am

fooljoe wrote:What no one here has addressed yet is how these panels will actually charge the car. Set aside for a second the fact that carrying around panels in the trunk instead of just installing them on your roof at home is terribly impractical...

You have 2 250 watt panels. That means you'll have maybe 350-400 watts of AC power available at a maximum (only for about 1 hour on the sunniest of days in summer). On L1, the charger requires 120v @ 12amps, or about 1400 watts. So how in the world do you expect to charge? I haven't tried this to be sure, but will the EVSE/charger operate at all if at least 12 amps aren't available? For most of the day you'd have barely enough power just to operate the cooling fan.

I suppose it may be possible to skip the inverter and get a DC-DC converter to step up the voltage from the panels to ~400VDC then feed it in (at a truly miniscule current) by splicing directly into the pack's DC lines, but I'm guessing you're not prepared to do this. The other option would be to store up a couple days worth of solar in a bank of 12v batteries, then feed it through your inverter when you get enough power to support L1 for maybe an hour, then repeat. How's your trunk looking now with a few car batteries thrown in with 2 giant panels and an inverter?

So, back to that first fact that we set aside. Just install some panels at home and tie them in with the grid. Switch to time of use metering. Then the panels will produce during peak hours when electricity is most valuable, and every small amount they generate can actually be used by your house or banked as credits. And they'll keep on producing even when you're not at work. Then charge your car in the middle of the night when electricity is cheap. Depending on your utility's rates and the season, you may be able to pull 5x as many kwh in the middle of the night as your solar produces on peak and still break even. Makes wayyyy more sense.

These are the specifications for my 1500 watt inverter. I can see that it can produce 120v @ 12amps in section 2.2
http://www.batterystuff.com/files/manual-S1500-24.pdf.

My solar panel also produce ~10 amps on an average day(connected in series: approx 30v @ 20 amps)
although they are rated as:

Open Circuit Voltage (Voc)37.7 V
Maximum Power at Voltage (Vpm)30.0 V
Short Circuit Current (Isc)9.10 A
Maximum Power at Current (Ipm)8.50 A
http://pvdepot.com/lg-255-watt-lg255s1c ... panel.html

I would need some other accessories like solar charge controllers. I have to research this.
Other than that I dont see why i cant do this. Please point out if i am wrong anywhere.

fooljoe
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Re: Solar Solution

Thu Nov 08, 2012 1:44 pm

malkit wrote:My solar panel also produce ~10 amps on an average day(connected in series: approx 30v @ 20 amps)
although they are rated as:

Open Circuit Voltage (Voc)37.7 V
Maximum Power at Voltage (Vpm)30.0 V
Short Circuit Current (Isc)9.10 A
Maximum Power at Current (Ipm)8.50 A
http://pvdepot.com/lg-255-watt-lg255s1c ... panel.html

I would need some other accessories like solar charge controllers. I have to research this.
Other than that I dont see why i cant do this. Please point out if i am wrong anywhere.
It doesn't matter how much power your inverter can put out - you're limited to the maximum power that your panels can generate, which as I said before is about 1/4 of what L1 charging requires.

Power=current * voltage. You say your panels can produce approx 30v @ 20 amps, which would mean 30*20=600W, which is of course wrong because their nameplate power is 510W, and that's only achievable at noon at the equator on a perfectly clear day, and it also doesn't take into account losses in the conversion to AC. But anyway, even if it were right, 30v @ 20a = 120v @ 5a. 5a is not going to cut it. And again, these numbers are the instantaneous, best case maximum. In reality, the power produced will be much less, and will bounce all over the place every time a cloud passes, etc. It just won't work.

The direct DC connection to the battery pack is probably the only way it could work, but you've got to "hack" the car for this, and yes look into charge controllers / DC-DC converters, etc. It's just not a good idea no matter how you slice it. I appreciate what you're trying to do by showing your co-workers how you can drive powered by the sun, but setting something like this up can be no more than just a gimmick. If you really want to pursue it maybe you can convince the building owner to build a solar canopy over a parking spot for you that feeds into the main building power and also has a charging station powered from the building main. Looks just as good to the coworkers and actually works.
RavCharge.com | 2012 Rav4-EV | 2011 Leaf SL w/QC batt replaced 11/20/15 | Clipper Creek CS-60 | EVSEupgraded 2013 Leaf EVSE | 3.84kw PV

DoxyLover
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Re: Solar Solution

Thu Nov 08, 2012 2:09 pm

malkit wrote:These are the specifications for my 1500 watt inverter. I can see that it can produce 120v @ 12amps in section 2.2
http://www.batterystuff.com/files/manual-S1500-24.pdf.

My solar panel also produce ~10 amps on an average day(connected in series: approx 30v @ 20 amps)
although they are rated as:

Open Circuit Voltage (Voc)37.7 V
Maximum Power at Voltage (Vpm)30.0 V
Short Circuit Current (Isc)9.10 A
Maximum Power at Current (Ipm)8.50 A
http://pvdepot.com/lg-255-watt-lg255s1c ... panel.html

I would need some other accessories like solar charge controllers. I have to research this.
Other than that I dont see why i cant do this. Please point out if i am wrong anywhere.
You're getting 20 amps at 30 volts - put that into an inverter and you'll get, at most, 5 amps at 120 volts, assuming no loss through the inverter. The inverter isn't going to make power, only change the ratio between volts and amps (also make it AC).

Sorry, that how it works.
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Reserved, quoted and ordered July 11, 2011
Delivered October 16, 2011 (Na. Plug-In Day)

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davewill
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Re: Solar Solution

Mon Nov 12, 2012 4:43 pm

I'm guessing he'll LOSE more from the added drag of the solar panels than he'd ever manage to actually generate and get into his battery...but I'd love to watch him try.
2014 Rav4 EV, Blizzard Pearl White
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AndyH
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Re: Solar Solution

Tue Nov 13, 2012 1:32 pm

An alternative view (who'da thunk?!).

Back in the S10E/Ranger EV days, one of the owners had a small wind turbine in the bed of the truck. He worked very near the coast and there was almost always wind during the 10-12 hours he was at work. He'd drive to work, park, extend and tilt-up the turbine, snap the guy lines to the truck and head in to work. It gave him some extra charge and also provided a very public demonstration that EVs are different in many ways.

Maybe the OP might consider a small trailer with three solar panels he could pop-out while parked. Seems to me that panels into a small inverter could feed the 120V L1 charge line. There would only be power when the sun was out, but direct PV to load is regularly done to pump irrigation water on ranches and to run a solar hot water circulation pump.

Marketing isn't efficient, but it'll take a LOT of marketing to expose more people to the reality of EVs.
"The stupid become extinct."-Bill Mollison
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fooljoe
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Re: Solar Solution

Tue Nov 13, 2012 5:19 pm

AndyH wrote:An alternative view (who'da thunk?!).
I wonder how many people asked him why he didn't try to drive with the turbine up...

Still though, unless you have a lot more than the 2-3 panels discussed here, I don't see how you could support an L1 charge. And even if you had a sufficient number of panels for, say, 3-4 hours a day on L1, then you'd be wasting power when they produced more than the ~1.4kw L1 requires. Charging this way via AC just seems completely unworkable without a battery bank as a buffer.

Gotta go with a direct DC connection. Chademo might work even (lol). Would be interesting to track down this guy and find out how he wired it up to charge.
RavCharge.com | 2012 Rav4-EV | 2011 Leaf SL w/QC batt replaced 11/20/15 | Clipper Creek CS-60 | EVSEupgraded 2013 Leaf EVSE | 3.84kw PV

AndyH
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Location: San Antonio

Re: Solar Solution

Tue Nov 13, 2012 6:54 pm

fooljoe wrote:
AndyH wrote:An alternative view (who'da thunk?!).
I wonder how many people asked him why he didn't try to drive with the turbine up...

Still though, unless you have a lot more than the 2-3 panels discussed here, I don't see how you could support an L1 charge. And even if you had a sufficient number of panels for, say, 3-4 hours a day on L1, then you'd be wasting power when they produced more than the ~1.4kw L1 requires. Charging this way via AC just seems completely unworkable without a battery bank as a buffer.

Gotta go with a direct DC connection. Chademo might work even (lol). Would be interesting to track down this guy and find out how he wired it up to charge.
If the goal is to get some charge into a battery while one is away from an outlet, why do we care if some of the energy is lost between the panel and the battery? We lose 95% of energy from burning coal from power plant to plug - we're certainly more efficient than that!

I'm not talking about ROI on the solar equipment here - I'm talking about adding charge to a battery that would otherwise not gain any charge at all.

A direct solar setup should be more efficient than a battery-based system anyway. Solar panels with a small MPPT board feeding a ~90% efficient inverter would provide electrons directly to the Leaf's charger. A battery-based system would require panels feeding a charge controller feeding a battery, which feeds an inverter and then the Leaf charger.

Sure, direct DC should be more efficient - but how many solar panels would one have to haul to hit 450-500VDC? Good luck with that on a portable system. ;)
"The stupid become extinct."-Bill Mollison
2018 Outlander PHEV
2015 smart Electric Drive (lease ended Feb, 2018)
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