What does better in low light?

[fungus]

I've heard claims from sellers of both amorphous and crystalline panels saying that 'their' technology works better in low light levels. Since I live in Scotland with clouds all the time which actually does work better in lower light levels?

[AbyssUnderground]

Neither really. Low light is useless for solar panels. Im in the UK also (Middlesbrough) and low light here on my panels yields very very little. Not even 50mA sometimes. This is (well was) with a 60w array. Im now down to 42w since a panel breaking.

[boB]

I think that if you gotta pick one for low light, the amorphous should do

a bit better.

Of course neither one will do great in low light.

boB

[TAH]

I have a lot of amorphous panels and only 6 single crystal panels. The amorphous panels will put out at least 40% of the rated power if you can see shadows. The single crystals put out almost nothing at the lower light levels.

[richhagen]

It would be interesting if one of us could log a comparison of output between the panel types at different light levels. Maybe it has already been done.  My perception, although not specifically tested is that the amorphous will reach charging voltage in lower light, but not put out much current, and that once you get to overcast, the mono-crystaline panels will overtake them. Without empirical data, I can not say for sure.  Even in a mostly cloudy location though I would be inclined to purchase the mono-crystaline 1st and polycrystaline 2nd before the amorphous.  My reasoning or belief is that while no types produce great power out of the sun, most of the main brand quality mono and poly crystaline PV panels with  25 year guarantees will likely be doing so much longer than any of the amorphous panels I have.  My only evidence to support this is that I have had to take more than half of my older amorphous panels out of service because of failures of the backing on the glass, or just no output even when they look fine.  I didn't get ten years out of them.  Newer panels may have better weatherability, I don't know, because I stopped buying them a long time ago.  Fungus, a good quality monocrystaline panel may very well still be producing power for you, even when YOU are old, providing you can keep it from getting broken or stolen.  Some of the Aarco panels I have were made in the early 80's, and still put out most of their rated power, I have no idea how long they will ultimately last.  They probably don't get as heavy of use here either in Chicago, which isn't exactly known for its year round sun.  Rich

[coldspot]

richhagen-

"because of failures of the backing on the glass, or just no output even when they look fine"

Could you please tell us more about this ?

Reason,

I have one panel, "MSX10 Solarex" model mmcaamwoo

Voc(V) 21.1

Isc(A) .62

Pnoct 9.0

Inoct .58

Vnoct 15.5

I can't get it so show more than 7-8 VDC open !

I'll test again today with this clear sunny n pure white background we have and see what is shows now.

Thanks

[cyplesma]

There's a company that has a slogan, "Without data it's just another opinion"

[AbyssUnderground]

That actually makes sense! Good slogan :-)

[coldspot]

OOP's-

In my hurry to post this morning before

heading off to work in this freezing cold!

(Not trying to jack this thread)

I forgot to add-

"because of failures of the backing on the glass"

This panel has fifted or swelling out and away paper type backing covering the hard rubbery panel back.

AFter looking it over more to add to post-

seems to just be a paper with a fair amount of dusty build-up and outlines of each cell browned into the paper from age I'd quess.

More quicky testing today with volt-meter on leads showed better volts than before !

(I hope the E-bay seller isn't a regular here)

 When I bought this and first testing was showing low output, I responded as such on the sale, They had only just listed with info from the panels tag.

I told them I'd be happy with a panel with out-put as item was listed, they said that after seeing my responce they would test them. And after such testing, that all of the lot had low out-put.

To get a better responce out of me they sent a check  for sale amount and told me to keep the panel.

So, I'm only into it for shipping cost.

But, this panel still only got up to 11.60 VDC about 4 PM this afternoon, was only 9. earlyer in what I thought was better light about noon. This was with the panel warmed up from ride around valley on the dash of truck. yes thru windsheild, have other panels that tested fine this way.

The better volts was after ride home in my pick-up that never gets warm and was not thru window but tested while walking to get inside. Retested thru house window showed 11.05 VDC

[richhagen]

On most of my thin films, the backing has weathered, and was not adequately protected.  I pulled one out and took a picture of the back for you.  





It may be that this problem has been solved with newer panels, I do not know.  I would think that simply coating the back with something would have offered some additional protection.  Rich

[richhagen]

As for the statistics, exactly 2/3rds of the panels installed, or 4 of 6 of the thin film panels have failed some were branded as ICP, whereas none of the commercially manufactured mono or poly crystaline panels have failed.  4 of the poly crystaline panels have been in service as long as the oldest of the thin film panels, although they've moved locations a couple times.  

Of 20 monocrystaline panels, which were all purchased used, at least 8 of them have a longer time in service by me than any of the 4 thin film panels, purchased new, that failed.  The only monocrystaline panel that failed, well actually it still output power, but I took it down because of damage, was the one I made from individual cells mounted between glass which got moisture in it not too terribly long after installation.  





The best dollars per watt in the long run thus far, after the local electric utility, are the commercially produced mono and poly crystaline panels even though the up front cost was higher.  

As for me, I am not looking to acquire any more thin film panels at this point.  Rich Hagen

[richhagen]

I am not sure if this was directed at my response, but in my post I did state the following:  "My perception, although not specifically tested . . ." and "Without empirical data, I can not say for sure." relating to the low light voltage, which should make the fact that it is an unproven opinion clear.  I still felt that giving what information I had would be of some benefit to the original poster, I am sorry if it did not meet your scientific criteria, I was not attempting to misinform anyone, only to be helpful by relating my past experiences.  At any rate, the main point of my reply was their premature failure rate. I got less than 6 years of service out of most of them.  I really did not mean any harm, Rich

[Bigbear]

I have 4-130 watt multi-crystalline panels from Kyocera, and they will put out about 3 to 4 amps even on real cloudy days.  In full sun, I have saw them produce about 30 amps.  Since we live in the woods, there seems to always be a tree limb making shade on the panels somewhere, and usually see about 15 to 18 amps on most days.  Right now the sun has dipped pretty low in the southern sky, and causes even more losses.  Just my 02 cents.

[fungus]

Do them panels have the silicon bare at the back of them rich? All the amorphous panels that I have have the silicon between two layers of glass, protecting them.. (except calculator cells lol) If not then I can easily see why they dont last long at all.

[ghurd]

I don't see much difference between them in overcast conditions.

That's for normal 36 cell PVs.  The low count, 32 or 33 cell panels don't do well in clouds, but those are now rare (for good reason).

Completely shading a single cell in crystalline panels has a serious effect, where shading a section of thin film has less effect, but clouds don't do that.

Rich's photos show just why I don't like thin film.  I had a bunch of Chronar (sp) PVs that did the same thing.  The UniSolar's usually have different failure problems.

Ever consider the possibility the battery could last longer than the panels?  LOL

The prices per watt in the US are similar between the 2 types anyway, so I see no reason for most people to bother with thin film.

G-

[richhagen]

Angus, these do not appear to have any backing just a coated pane of glass.  Rich

[richhagen]

In looking at them again, two of the ones that failed are more or less bare, and two have some type of white thin plastic layer stuck to the back of them, almost like a sticker.  Of the two still in use, one is more or less bare like the one in the photo, only with less damage as it is still in the process of failing, and the other I am not certain unless I climb up and look at it.  Rich

[coldspot]

This multi crystil one

some type of white thin plastic layer stuck to the back almost like a sticker.

OK, to test for Amp out-put-

multi meter in-line not across

a resistor for a load, what value?

please

Thanks

[ghurd]

The sticky plastic is Tedlar. Removing it shouldn't be too bad, but it could be a moisture barrier.  The old Siemens PVs had it fall off if the PV got too hot.

Test the PV into a battery. Outside, in good sun, about noon, pointing at the sun.

[TAH]

I have some chronar thin films and they are just a layer of glass with some plastic type backing. I also have EPV panels and they are two layers of glass that is produced the same way as a car windshield. They have a twenty year warranty. I will probably be getting more of them since the cost per watt is way less than even the cost of old used panels on Ebay. I also have half of them on a 10:12 pitch roof facing south west and they have been averaging over 3 hours of full output a day for the last two months according to the controller they are conntected to even though the pitch and direction are completely wrong for this time of year.

[Gordy]

Bigbear,

 It seams a shame to me, to make a investment like that and not get full use of it. How far out have you moved the pay back period for your system with the shading issue??? Assuming you can't move or raise the panels to get clear sun, I'd invest in a chain saw  or at least a ploe saw to remove offending limbs if not the hole tree.

Gordy