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Discussion Starter · #1 ·
Has anyone tried those new "flexible" solar cells?

I've been installing regular silicon cells (polycrystaline) on my cars for while now, and I have never had a problem with them, until these last three snow storms we had. One of my hoods actually collapsed from having almost three feet of heavy, wet snow on it (and of course all the cells cracked and broke) but my other car, which hardly had a foot of snow on it came out looking like this.

I'm not sure if they cracked due to the weight of the snow bending the hood, or it was temperature related.... but I'm willing to bet it's the hood bending from the weight. I used 2-part epoxy to hold them onto the hood, then two coats of non-UV clear on top of them to protect and seal them.

Does anyone who tried this have any ideas, or should I just go with the flexible panels that they are now selling??? And how do they make the panels flexible? If they are crystaline cells, then won't they crack as well?

- Paul
 

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Has anyone tried those new "flexible" solar cells?

And how do they make the panels flexible? If they are crystaline cells, then won't they crack as well?
There are some variations in the 'how' question .. but in short , some are not crystalline ... these can be very durable ... some will not crack ... they can still be damaged and stop working ... but some of them can take allot of flexing and allot of punishment.

Don't forget the roll the adhesive will play as well ... the adhesive will also have to allow for flexing ... if the adhesive cures ridged, it will impair the ability of the flexible cells to flex.

Now for the bad ...
The flexible cells are significantly more expensive $ per watt of power.

The flexible cells are significantly less efficient and will produce less electrical energy under the same conditions and coverage.

Many of the flexible cells degrade much faster over time than the crystalline variations do... so 20 or so years from now don't expect the same kind of 80% initial power output many of the crystalline style cells offer.

So there will be a trade off.

Are there specific flexible cells you are looking at?
 

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Discussion Starter · #3 ·
Here's what I don't understand...

I know that thin film cells can easily be made into flexible materials, because they are essentially sprayed on (there's more to it than that, but...)

The problem is that thin film isn't worth using on cars because the efficiency is extremely low (maybe 7% ???) and would not even make a difference for your batteries. Now take a look at these:

http://cgi.ebay.com/NEW-80W-Flexible-Mono-Solar-Panel-12V-Battery-Charge-/130486935588

These are monocrystaline cells, but they are flexible. Now, from what I see, they are basically the same type of crystaline cells that I have on my car. How come those give a little, and mine wont? I tested the epoxy, and it gave a lot more than the cells did. It didn't snap until well after the cell did.
 

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How well were they sealed. Is it possible water seeped in under the cell and froze breaking out the cell area? Also wonder if the issue could be the uneven application of a hard epoxy and thermal expansion of the under laying metal that caused the cells to crack.

I would be skeptical of the flexibility implied in the picture if the cells used are Monocrystalline. The majority of flex would be between the cells not the actual cells. I think they mean they are encapsulated in a flexible medium.
 

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The problem is that thin film isn't worth using on cars because the efficiency is extremely low (maybe 7% ???) and would not even make a difference for your batteries. Now take a look at these:

http://cgi.ebay.com/NEW-80W-Flexible-Mono-Solar-Panel-12V-Battery-Charge-/130486935588
From the pictures ... it looks to me like the cells are ridged , and the panel flexes at the joints between cells... so the panel is flexible but not the cells themselves... But some of the usual details are missing ... like power warranty information ... craftsmanship warranty information ... amount of flex tolerance , etc ... You can always write them and ask for more details... but without additional details I would not risk the ~$433 for 80 Watts ... ~$5.41 / watt is not particularly good.

I agree the true flexible cells are low efficiency , high cost , high degradation.... but high flexibility and high durability... it is a trade off.
 

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Discussion Starter · #6 ·
From the pictures ... it looks to me like the cells are ridged , and the panel flexes at the joints between cells... so the panel is flexible but not the cells themselves... But some of the usual details are missing ... like power warranty information ... craftsmanship warranty information ... amount of flex tolerance , etc ... You can always write them and ask for more details... but without additional details I would not risk the ~$433 for 80 Watts ... ~$5.41 / watt is not particularly good.

I agree the true flexible cells are low efficiency , high cost , high degradation.... but high flexibility and high durability... it is a trade off.
From what the ebay picture shows, the cells are actually bending with the lamination.... which seems strange, because crystal cells do not bend very much (without braking).

I could try to do the same thing... put a very thick coat of clear on. The urathane auto enamel I used is very thin..... I think if I had used a heavier enamel and applied it thicker, they may have flexed with the hood instead of cracking.

I think what really killed it was that it rained after the 1+ foot of snow we got that day. The snow, soaked with rain, was extremely heavy... there must have been at least 400 pounds of snow on that hood -- no joke. Normally, it either rains or snows, but not both.
 

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I could try to do the same thing... put a very thick coat of clear on. The urathane auto enamel I used is very thin..... I think if I had used a heavier enamel and applied it thicker, they may have flexed with the hood instead of cracking.
That would help distribute the force over the cell better ... but will still give at the weakest point

Probably best to test a bit on some of your broken cells to see how much improvement you can get... before investing in the idea to any large amount of $.

I don't see significant flexing of the cells themselves in their ebay pictures or on their main web site page ... but that is just my point of view.
 

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Discussion Starter · #9 ·
The answer may be to put reinforcing under your hood to stiffen it.
I know, I though of that but it's a shame that you have to stiffen a stock hood.... you think they would have built it to withstand the elements from the factory :mad:

Although you can't really tell in the pictures, the hood itself DID get permanently warped from the weight of the snow. Dang shame.

On the flip side, the cells are pretty cheap... about $2 each. I've broken them before (by accident), but never that many at the same time! I think a really, really, really heavy coat of clear may help.
 

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PZigouras

I like the idea of incorporating solar cells to my project and interested in how this turns out as far as the best way to install and seal the cells on top of a car.

I was thinking of just running them to the 12v aux battery to reduce the power through dc to dc conversion and in affect draw less power from my main pack. I would be interested in the results you have seen in real world application and where you purchase your cells.
 

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PZigouras

I like the idea of incorporating solar cells to my project and interested in how this turns out as far as the best way to install and seal the cells on top of a car.

I was thinking of just running them to the 12v aux battery to reduce the power through dc to dc conversion and in affect draw less power from my main pack. I would be interested in the results you have seen in real world application and where you purchase your cells.
Are your solar cells powering your 12 volt battery or traction pack?
 

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Discussion Starter · #12 ·
I use 48 cells (24 x 2 in parallel) in this car to charge my 12V accessory battery. I actually never have to plug in the 12V charger, because it gets almost 100 watts continuously when I park it outside.

My Explorer has 150 cells (about 80 volts total) that charge my 144V primary battery pack. I push the 80V into a low frequency 2;1 transformer then rectify it to get about 160V worth of charge. There's no charge controller so, in theory, it could someday overcharge the pack, but that'll take weeks.... so I'm not worried about it. Plus they are flooded batteries, so I don't think they really care too much about a few extra volts.

- Paul
 

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There are flexible panels that roll up, like a roll of paper.

Also, New design of Roofing Shingle have cells in them. Plug and play so I am told. No links, no proof. Do a Google.
 

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There are flexible panels that roll up, like a roll of paper.

Also, New design of Roofing Shingle have cells in them. Plug and play so I am told. No links, no proof. Do a Google.
These flexible rollups are very low efficiency. And actually using any solar cell is not really worth it for a car. EXCEPT the bragging rights as you can very easily convince passersby that the solar cell contributes A LOT to running the EV and they also will assume you are running for free.

Francis
 

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Discussion Starter · #15 ·
These flexible rollups are very low efficiency. And actually using any solar cell is not really worth it for a car. EXCEPT the bragging rights as you can very easily convince passersby that the solar cell contributes A LOT to running the EV and they also will assume you are running for free.

Francis
I disagree that they have no practical uses. It my case, it eliminated the need for a DC-DC converter, and I never really have to plug in the 12V vehicle battery.

As far as range goes, an extra 100 watts obviously will not help any... but for some people, it can help in other ways. For example, if you keep your car parked outside while you're at work, even 100 watts will help... especially if you are parked there all day (9 hours, for me).

Speaking of range, I will soon be upgrading my friend's 1998 Suburban with solar cells, in hopes that it will boost his range. Our goal is to install 1 kW worth of cells on the truck. We did the math and we cannot hit that figure with just the roof (not enough surface area), but I am hoping that if we add in the hood, we may just hit 1000 watts. The hood on that truck is massive, so I'm hoping we can get at least close to that. I'm also hoping that we can match the array's voltage with his battery pack, to eliminate the need for a transformer.

This is my biggest project yet, and I will post pictures as we go along. If this works, I'm sure that the 1kW of continuous power will at least boost the range a little.... but there's only one way to find out! :D
 

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I disagree that they have no practical uses. It my case, it eliminated the need for a DC-DC converter, and I never really have to plug in the 12V vehicle battery.

As far as range goes, an extra 100 watts obviously will not help any... but for some people, it can help in other ways. For example, if you keep your car parked outside while you're at work, even 100 watts will help... especially if you are parked there all day (9 hours, for me).

Speaking of range, I will soon be upgrading my friend's 1998 Suburban with solar cells, in hopes that it will boost his range. Our goal is to install 1 kW worth of cells on the truck. We did the math and we cannot hit that figure with just the roof (not enough surface area), but I am hoping that if we add in the hood, we may just hit 1000 watts. The hood on that truck is massive, so I'm hoping we can get at least close to that. I'm also hoping that we can match the array's voltage with his battery pack, to eliminate the need for a transformer.

This is my biggest project yet, and I will post pictures as we go along. If this works, I'm sure that the 1kW of continuous power will at least boost the range a little.... but there's only one way to find out! :D
Keep us informed. I can fit 1000 watts on the rack of my Ranger so I know it is possible. I bet that Suburban is heavy. :eek:
 

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Don't get me wrong, I am a solar guy and off the grid and have 109 x 195Watt panels, 9 charge controllers, 3 inverters, running my welding/fabricating shop and plan to charge my EV Yaris with solar.

But for me my 144v pack charges up the Aux Battery through the Dc/Dc converter and I will have a small solar panel on the dash to keep the Aux battery feeding electrons to the clock and misc stuff when parked. I figured it was such a trade-off sacrificing the Aerodynamics of the EV by mounting large panels and so little to gain.

Francis
 

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Here is something that seemed to work for short trips:

http://evalbum.austinev.org/838

According to their website:

"From June to November 2000, 2001 and 2002 the SBB traveled an average of 50-80 miles per week using only energy gained directly from the sun (about 10-15 miles of free driving per day). It cost literally nothing to drive and produced virtually no air pollution for a period of six months each year."
 

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flexible solar cells are a great new technology. Im loving how the solar energy generation technology just keeps advancing, and not only getting better but getting cheaper too. For starters it was the regular solar panel, then its the solar concentrators, then also the portable solar panels, for camping and such, and now thin film panels that can be moulded to fit all sorts of interesting new applications. Whats next?
 

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I was thinking of a 1kw array on my ranger . at 5.9 hours/day yearly average sun at full power . 10 days would be a full charge (50kwh). better in summer and much less in the dead of winter . thinking of glued on clear coated monocrystalline cells with a fold-out set to augment output . cell weight is not much with out glass .
 
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