Author Topic: Panels not working to full capacity  (Read 5339 times)

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AbyssUnderground

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Panels not working to full capacity
« on: July 15, 2006, 12:20:52 PM »
Hi all,


Ive got 6 1.5w 12v panels and none of them seem capable of 125mA which is what they should give out at full capacity. They are all brand new and were bought staggered over a 5 month period (2 5 months ago, 1 3 months ago, another 2 months ago and 2 today). Ive disected 2 of them out of their cases (the pic below shows them). Even when in their case they only gave around 30mA, and out of their cases they give the same.


I measured this with a short circuit with my multimeter. I also tested by putting a 60mA load onto each and measured the voltage across it while its under load, which came out at 8.5v. They all give 21.5v open circuit and the sun was at as bright as you could ever get it, not a cloud in sight. They were pointed directly at the sun and I moved them round to see if a different angle helped. It didnt. I can't understand why none of them are putting out what they are rated at.


Any ideas?


Pic:


« Last Edit: July 15, 2006, 12:20:52 PM by (unknown) »

drdongle

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Re: Panels not working to full capacity
« Reply #1 on: July 15, 2006, 06:33:38 AM »
They lied?
« Last Edit: July 15, 2006, 06:33:38 AM by drdongle »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #2 on: July 15, 2006, 07:12:47 AM »
They are a reputable company, I cannot see why they lied. If they did I could go to trading standards over it. Its false advertising.
« Last Edit: July 15, 2006, 07:12:47 AM by AbyssUnderground »

TomW

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Re: Panels not working to full capacity
« Reply #3 on: July 15, 2006, 07:52:23 AM »
Abyss;


Well, I have 300 watts [marketer rated] solar panes [Siemens] and they only put out about 240 watts true. This is fairly well understood rating system.


Since you gave no DETAIL I cannot know if the numbers fit the normal rating methods.


You do realize how insignificant that low power is and connections could eat it up very easy? Bad connections, reversed diodes, lots of ways to knock output in the head.


More info may find your problem before you go complaining. Open volts multiplied by shorted amps gives the advertised wattage of most panels. If you get 80% of that in full on sun perpendicular to the panel on a cool day consider yourself lucky.


Just reality.


More information is needed.


TomW

« Last Edit: July 15, 2006, 07:52:23 AM by TomW »

willib

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Re: Panels not working to full capacity
« Reply #4 on: July 15, 2006, 07:53:55 AM »
The ratings for solar panels has allways been  a bit inflated , as i've never got what my two panels are rated at

 i think they rate them as if they were in a desert, at noon , on a mountain , at a time of year when the earth is closest to the sun

only then could they maybe put out what they were rated at

sorry to disappoint
« Last Edit: July 15, 2006, 07:53:55 AM by willib »
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AbyssUnderground

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Re: Panels not working to full capacity
« Reply #5 on: July 15, 2006, 09:46:25 AM »
21.5v * 0.03A = 0.645w


Not even half what they are supposed to be.


What it says on the box:


Specs: 1.5W @ 17.5V

Test Condition: AM 1.5 100mW/cm2

Cigar lighter plug fuse: 0.5A

Cable length: 2.7m (9ft)

Dimensions: 325x125x14


It isnt a branded panel but is sold by a reputable company.


If there is any more info that would help let me know.

« Last Edit: July 15, 2006, 09:46:25 AM by AbyssUnderground »

dinges

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Re: Panels not working to full capacity
« Reply #6 on: July 15, 2006, 09:55:17 AM »
I agree with the other posters, ratings for PV panels usually are a bit optimistic.


However, your 1.5W panel must be very similar to mine (which is 125mA too). Made in China (surprise), but works ok. Used for keeping batteries of cars charged up. Price about 25$ over here.


Mine put out about 100mA in full sun. Your 30mA seems VERY low, even accounting for optimistic ratings. It's about a quarter of what they're supposed to deliver.


What I did notice is that some of the single cells (at the beginning and end) are hidden under the cover, i.e. in the dark. Also, I've noticed that these (and other panels) drop VERY rapidly in output power as just even a little shadow falls on a single cell.


Which has always made me wonder: how can it be that the darkness (of the case) on the first and last cells don't limit output of the entire PV panel?


Sorry, not really an answer, more like another question...


Peter.

« Last Edit: July 15, 2006, 09:55:17 AM by dinges »
“Research is what I'm doing when I don't know what I'm doing.” (W. von Braun)

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #7 on: July 15, 2006, 10:32:47 AM »
And a good question too. Like I said in my original post, Ive removed two from their cases so the whole panel is visible and I still get the same results. Seems like I can't answer your question either.
« Last Edit: July 15, 2006, 10:32:47 AM by AbyssUnderground »

willib

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Re: Panels not working to full capacity
« Reply #8 on: July 15, 2006, 10:48:49 AM »
i dont know what the AM 1.5 is ?

but there are 10,000 sq cm in 1 sq meter times .1W = the standard 1000 Watts / square meter..

« Last Edit: July 15, 2006, 10:48:49 AM by willib »
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Flux

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Re: Panels not working to full capacity
« Reply #9 on: July 15, 2006, 11:27:21 AM »
Solar panel rating is confusing at best.


The standard insolation is 1000Wper sq Metre, something that many of don't see often if ever.


The other catch is that they measure the output at a specific panel temperature which is low ( 25 deg C ?)


In most places a panel seeing the standard insolation will be much hotter than the test temperature.


It is not likely that many will ever see the rating of a panel that meets its spec.


This is at the maximum power point and power into a battery will be a fair bit less.


Decent manufacturers get close to their rated figures but I have seen claims that not all samples of panels meet the rated output.


Cheap, mostly amorphus silicon panels, fall way below claimed spec, and they get away with it because the user has no means of proving them wrong. Small low power panels are less likely to be checked than large and expensive ones.


I think you are unlucky and have some that are way worse than you would reasonably expect. To prove it you will need to send them to someone certified to test them and it will cost you money and hassle, the makers are relying on this.


I think these are so obviously below spec that you would have been justified in taking them back but you should have done it immediately.


The world is full of scams, wind power is worse than solar.

Flux

« Last Edit: July 15, 2006, 11:27:21 AM by Flux »

dinges

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Re: Panels not working to full capacity
« Reply #10 on: July 15, 2006, 12:48:49 PM »
Do you have a picture of the PV panels with the original housing? Could be interesting for a few other readers on this board to know when to start being careful.


And I've got a strong feeling that the panels you have come out of the same factory as mine... In fact, I've got several modules the housing of which looks slightly different, but the PV elements themselves are so similar that it's very likely they're from the same factory.


Anyway, here's my panel:


http://www.produktinfo.conrad.com/datenblaetter/850000-874999/857030-an-01-en-Battery_Saver_SE_2_Wat
t.pdf


made by this company: www.icpsolar.com


http://www.solarcharger.com/s.nl/it.A/id.64/.f?sc=2&category=62


Cost me 20E (25$) on offer; normal price 30E. 15$/Watt...


The specs say 135mA at 15V; my multimeter says 100mA (in a battery). That is, in the summer, with panel manually adjusted to be perpendicular to the sun.


Nice gadgets, but more of a play toy than anything serious. Way overpriced. Waste of money, to be honest. Yet cool to have available, every now and then.


Peter.

« Last Edit: July 15, 2006, 12:48:49 PM by dinges »
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wooferhound

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Re: Panels not working to full capacity
« Reply #11 on: July 15, 2006, 01:42:27 PM »
I would try putting 3 sets of 2 in series and then Parallel the three sets to try and improve your output.
« Last Edit: July 15, 2006, 01:42:27 PM by wooferhound »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #12 on: July 15, 2006, 04:01:40 PM »
What would making them series acheive? They work on their own they just dont give out much current. I think all panels probably come from the same factory to be honest. It says "made in china" on the box.


Yours are similar to mine. The LED on mine is always flashing (cannot be turned off) which is a waste of power (one reason im removing them from the case).


If you need to see a pic of them in side their cases there is one on the link HERE

« Last Edit: July 15, 2006, 04:01:40 PM by AbyssUnderground »

QUAZ HOLT

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Re: Panels not working to full capacity
« Reply #13 on: July 15, 2006, 04:47:12 PM »
Abyss, do these units have a small circuit or are you running your test directly from the cells. The connection to these cells is very fragile. Bill
« Last Edit: July 15, 2006, 04:47:12 PM by QUAZ HOLT »

QUAZ HOLT

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Re: Panels not working to full capacity
« Reply #14 on: July 15, 2006, 04:54:32 PM »
Abyss, Just another note. Might be your meter. Just a guess. Bill
« Last Edit: July 15, 2006, 04:54:32 PM by QUAZ HOLT »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #15 on: July 16, 2006, 02:05:20 AM »
i re-soldered the cells I took out but the others are still factory sealed. I doubt its my meter as it can't even power a 60mA load properly.
« Last Edit: July 16, 2006, 02:05:20 AM by AbyssUnderground »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #16 on: July 16, 2006, 03:58:57 AM »
Just had a thought:


Will putting them behind double glazing have any effect on the power they produce? They windows are clean so as much light as possible can get through.

« Last Edit: July 16, 2006, 03:58:57 AM by AbyssUnderground »

tsakach

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Re: Panels not working to full capacity
« Reply #17 on: July 16, 2006, 04:03:20 AM »
Looking at the photographs, it appears that there are about 30 "cells" per panel. Since the cells are connected in series, the current of the panel is limited by the cell with the least amount of current. For instance, if one of the cells has a current of 65ma, then the entire panel will have a current of 65ma, but the panel voltage will equal the sum of the voltages of each cell. When building panels, you need to measure the output of each cell and discard cells with reduced current.


Another thing I noticed in the picture is that the cells on each end seem to be 1/2 the width of the cells in the middle of the panel. Is this the case? Smaller cell area = less current but voltage is still the same. If the panels happen to be cut in the wrong place it might explain why the entire panel has reduced current. You might be able to measure the current of the cells in the middle only. Also, if you can measure the current of individual cells in the panel, you should see something more like 100ma. If all the cells have an output around 65ma then the rating of these panels is way off.

« Last Edit: July 16, 2006, 04:03:20 AM by tsakach »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #18 on: July 16, 2006, 04:15:24 AM »
That is correct, there is "half" a cell at each end. Unfortunately I cant split the cells or even check their individual voltage/current.
« Last Edit: July 16, 2006, 04:15:24 AM by AbyssUnderground »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #19 on: July 16, 2006, 04:51:28 AM »
I just tested the panels outside, and not through the double glazing, and guess what, the outputs doubled. :-)


It seems double glazing was the culprit.


I managed to get:



  1. disected panels - 63mA and 96mA
  2. undisected panels - 101mA, 114mA, 92mA and 97mA


All except the first are close to the rated capacity so Im now a lot happier than I was before.


Thanks to all the people who posted and attempted to help me with the problem. This board is priceless :-)

« Last Edit: July 16, 2006, 04:51:28 AM by AbyssUnderground »

kitno455

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Re: Panels not working to full capacity
« Reply #20 on: July 16, 2006, 08:56:57 AM »
you were testing the panels INDOORS?


allan

« Last Edit: July 16, 2006, 08:56:57 AM by kitno455 »

TomW

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Re: Panels not working to full capacity
« Reply #21 on: July 16, 2006, 09:16:12 AM »
allan;


That is why responding to some posts [or allowing them board space] is a huge waste. Incomplete info and unrealistic expectations.


It is not rocket science or any kind of secret that panels are rated for full outside sunlight perpendicular to the sun.


Just my opinion.


Cheers.


TomW

« Last Edit: July 16, 2006, 09:16:12 AM by TomW »

dinges

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Re: Panels not working to full capacity
« Reply #22 on: July 16, 2006, 09:44:55 AM »
Yes... Felt the same as you did, Allan...
« Last Edit: July 16, 2006, 09:44:55 AM by dinges »
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AbyssUnderground

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Re: Panels not working to full capacity
« Reply #23 on: July 16, 2006, 09:47:31 AM »
Unfortunately NOT EVERYONE knows that so why rant and rave about it?


I did state that they were through glass and asked whether it would cause a problem. I assumed not because glass lets light through, which, incase nobody had noticed, the panels use!

« Last Edit: July 16, 2006, 09:47:31 AM by AbyssUnderground »

dinges

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Re: Panels not working to full capacity
« Reply #24 on: July 16, 2006, 09:51:40 AM »
Easy now, Abyss.


Not ranting and raving, just utterly surprized.

« Last Edit: July 16, 2006, 09:51:40 AM by dinges »
“Research is what I'm doing when I don't know what I'm doing.” (W. von Braun)

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #25 on: July 16, 2006, 10:13:18 AM »
I didnt mean to "lash out" like that. It just annoys me that you (and others) expect people to know things like that.


According to my father, double glazing now has to have a "tint" to it to stop harmful UV rays. This is probably why they didnt perform as well. But Im now happy they do perform better outside and this is probably where they will go once they are mounted.

« Last Edit: July 16, 2006, 10:13:18 AM by AbyssUnderground »

QUAZ HOLT

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Re: Panels not working to full capacity
« Reply #26 on: July 16, 2006, 07:31:54 PM »
AbyssUnderground, Looks like the meter in your head is not working. Maybe you should get above ground for a while. Bill
« Last Edit: July 16, 2006, 07:31:54 PM by QUAZ HOLT »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #27 on: July 17, 2006, 04:47:33 AM »
Excuse me?
« Last Edit: July 17, 2006, 04:47:33 AM by AbyssUnderground »

Gary D

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Re: Panels not working to full capacity
« Reply #28 on: July 17, 2006, 07:55:57 AM »
Glass usually looses you 10% per layer of potential solar- depending on the glass makup. On many solar hot air/ solar hot water systems this is ok and even preferable, due to needing a high operating temperature during winter. The V.W. panels talked about on this site frequently are usually placed on the dash and plugged into a cigaret lighter plug. Thus the confusion I think. They don't want to scratch the new paint jobs, resulting in loss of potential power.... Giving both sides of this "ahem" discussion a chance, it wasn't till post 16 that the double glazing was mentioned. I think this thread should stay just becouse not everyone understands that even outside, panels will perform better if a periodic dusting is done; it will increase output... Thought from the cheap seats here. Everyone please mellow out a bit. Problem was solved, some might have learned something too! A similar question might not now be asked (by someone else) for a week or more! ;-)  Gary D
« Last Edit: July 17, 2006, 07:55:57 AM by Gary D »

AbyssUnderground

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Re: Panels not working to full capacity
« Reply #29 on: July 17, 2006, 09:01:40 AM »
I certainly learned something... Panels work best outside not behind glass :-)
« Last Edit: July 17, 2006, 09:01:40 AM by AbyssUnderground »

Ungrounded Lightning Rod

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Re: Panels not working to full capacity
« Reply #30 on: July 17, 2006, 07:27:08 PM »
Better window assemblies are also tinted to reduce infrared transmission and thus reduce heat loads in the summer and heat loss in the winter.  This may easily lose you 1/2 to 2/3s of your light (and thus your current), even if the dimming effect isn't particularly visible to the naked eye.
« Last Edit: July 17, 2006, 07:27:08 PM by Ungrounded Lightning Rod »