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paulz
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# Posted: 31 Aug 2018 05:39pm
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A friend gave me this panel yesterday. Must have had a branch hit it but it still works fine. Can I just put clear silicone or tape on it, no potential danger?
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ILFE
Member
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# Posted: 31 Aug 2018 11:08pm
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Even blocking a single cell will seriously hamper the output of a solar panel.
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darz5150
Member
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# Posted: 31 Aug 2018 11:12pm
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Maybe creeky can look at the specs in your second picture and tell you more about the charge controller and what batteries to use. And also about possible repair options.
The panel was free. But figure out how much it will cost to get it hooked up and putting out electricity for you.
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ICC
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# Posted: 1 Sep 2018 12:32am - Edited by: ICC
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The is a reasonable chance that only the tempered glass overlay sheet is cracked and the cell itself is okay. The potential for water getting in there and causing grief is the big worry. See if you can find a supplier of transparent laminating film. Orafol makes several of these films. Sometimes a sign shop will sell you a piece off a roll. Some of the varieties are used to make those graphics that get applied to car and truck bodies, others are used to laminate a printed sign and make it more weather resistant. There are also varieties that are sold as a stone guard material to be used on the front of a trailer. They can be clear to let color show through; some are colored, you don't want them. 
You wrap the entire panel front with it and turn the edges under to the backside. Seal and shrink it to fit with a heat gun. We used some that had a claimed life of 8+ years. That was two years ago and the film still looks clear and has stayed attached.
You say the works but how was that arrived at? Bothan amp and a voltage check against specs? Volts only means little but is easy to do. Just does not mean much without knowing if it can also produce the rated amps.
In bright sun the panel volts output should be in the neighborhood of the Voc rating, 44.5 volts. If you have a multimeter with the ability to measure at least 10 amps you can check the short circuit amps. That panel in bright sun should give you about 8.5 amps, the Isc value on the label.
Then if you have no other solar equipment you will need batteries and a charge controller to use the panel.
Keep in mind that if you want to add more panels to be used with this one best results are to use the same panel brand and model. At the very least the amps (Imp) output and the volts (Vmp) output of other panels should be within 10% of the ratings for this panel.
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paulz
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# Posted: 1 Sep 2018 11:12am
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Thanks guys. Voltage was in the 30s in patial sunlight but I'll check in full light today (if we get some) along with shorted amps.
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ILFE
Member
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# Posted: 1 Sep 2018 12:43pm - Edited by: ILFE
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Quoting: paulz Voltage was in the 30s in patial sunlight...
Well, if not connected to anything, the panel should be showing closer to its open circuit voltage.
Quoting: paulz ... I'll check in full light today (if we get some) along with shorted amps.
The next direct sunlight you have, definitely plug the MC4 connectors into each other and throw a clamp-on ammeter around the connection, and have a look.
I'm curious to see what the output is, myself, if you get a chance to check it.
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paulz
Member
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# Posted: 1 Sep 2018 02:20pm
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11am and sunny. 43 volts but only 2.5 amps. I have the cheesey red. HF ammeter in series.
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ILFE
Member
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# Posted: 1 Sep 2018 02:32pm
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Quoting: paulz 11am and sunny. 43 volts but only 2.5 amps. I have the cheesey red. HF ammeter in series.
Wow. That's way short of the ISC. Maybe, just to be on the safe side, see if you can find another ammeter to try? If you do much work regarding electrical, you can never have too many meters, for sure.
Well paulz, at least you had a chance to check it, before disposing of it.
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paulz
Member
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# Posted: 1 Sep 2018 07:56pm
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Thanks ILFE. I'm back home now, have a better meter here but won't get back out to test until next week. Will let you know. Not knowing how these things work, seems odd to have all the voltage but not the amperage.
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creeky
Member
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# Posted: 1 Sep 2018 08:38pm
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I have no idea what to do with that panel. I have only seen shattered face sheets on a solar panel once.
But if you could get it water proof it would be neat to put it on a potting shed with a tiny 10a solar controller a couple of lithium tool batteries and a tiny invertrr. Lights, charge your power tools etc.
I'VE been kicking the idea of a solar powered garden shed for awhile. You could put the thing anywhere. Pump water. Light up a yard.
Free panel is sure a good start.
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ILFE
Member
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# Posted: 1 Sep 2018 09:39pm
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Quoting: paulz ... won't get back out to test until next week. Will let you know.
I will be patiently waiting. 
I am interested to see if this issue may be more due to the meter, or, if it is a bad panel. Unfortunately, I am thinking the latter, especially considering the guy having replaced it.
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darz5150
Member
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# Posted: 1 Sep 2018 10:05pm
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Dont you need a load to measure the amps?
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ICC
Member
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# Posted: 2 Sep 2018 12:00am
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PV panels are unique electrical devices in that you can short circuit them, connect the positive and the negative outputs, and not damage the panel. That is why they have a short circuit amp --- Isc.
As ILFE suggested, plugging the pos and the neg into each other and using a clamp meter is the easiest, but most people don't have a clamp meter. People with solar should though. Clamp meters also have leads like std meters.
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offgrididaho
Member
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# Posted: 2 Sep 2018 02:48pm
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Definitely test the current with a clamp meter or inline meter capable of testing 10a DC. I have had bad panels that give out decent short circuit voltage but their short circuit amperage is way lower than it should be.
Either test the short circuit amperage or hook panel directly to a battery (that needs charging or has a load on it already like headlights on your car) and see what your true amperage is before committing to using this panel.
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darz5150
Member
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# Posted: 2 Sep 2018 09:30pm
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Hey Paul. If you get it figured out if the panel is working and worth saving. Maybe you could see if a windshield repair shop could repair/reseal it just like a cracked windshield. Just a thought.
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paulz
Member
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# Posted: 13 Sep 2018 10:31pm
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Sorry for the late reply. Had a chance to test the panel again in full sunlight with a couple of meters. Still only 2.5 amps shorted, also hooked up a 12.2 car battery and amps went to 1.75.
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ILFE
Member
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# Posted: 14 Sep 2018 03:36am
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Quoting: paulz Sorry for the late reply. Had a chance to test the panel again in full sunlight with a couple of meters. Still only 2.5 amps shorted, also hooked up a 12.2 car battery and amps went to 1.75.
Sadly, I am afraid that panel is about useless.
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paulz
Member
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# Posted: 14 Sep 2018 10:41am
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Ah well, easy come easy go. I'm still in the early stages of solar strategy as my sunlight is very limited. There are many, many ads on my local Craigslist (SF Bay Area) for solar panels, new and used, either due to local solar companies, Silicon Valley, wealthy people, don't know, but for someone who knows how to shop for them there are probably some real deals.
I was reading that there have been advances in panels that do well (40% efficiency?) in indirect sunlight, that might be something for me.
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ILFE
Member
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# Posted: 15 Sep 2018 09:33pm
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Quoting: paulz I was reading that there have been advances in panels that do well (40% efficiency?) in indirect sunlight, that might be something for me.
I don't typically keep up on current pricing, efficiencies, etc. But, the average efficiency I believe most are at, would be around 18%? ICC, Creeky, or others, may be able to verify the actual numbers for you.
With that said, prices of panels here in Cambodia, are about .64c / watt, currently. A buddy recently purchased some for his farm, and relayed the costs of his system to me.
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ICC
Member
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# Posted: 15 Sep 2018 09:59pm - Edited by: ICC
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A friend got some LG panels this summer with a claim of 21.something % efficiency. The biggest gain with higher efficiency is the smaller footprint an array takes. They still need good, full sunshine. The ratings are all arrived at using 1000 watts per square meter sun exposure.
Unless you have a small roof more panel efficiency is really not a big deal; makes a difference of maybe 14 panels instead of 15. I've not heard of 40% panels, but don't keep up on the latest news. I can imagine 40% would be pricy panels if available today otherwise we would hear more about them, see them on the market.
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