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Old 11-30-2014, 07:54 PM
Lurch Male Lurch is offline
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Default How long do panels last?

I have been using the same solar panels for the past 18 years. They appear to be working. How do you know when they go bad? Is it a sudden thing, or is it gradual? Will just one panel go bad, and not the others? If just one goes bad, will you notice the system being weaker? Will an individual voltage test of the panels tell you what you need to know?
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Old 12-01-2014, 12:54 AM
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DavidOH Male DavidOH is offline
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Lightbulb Check it's output.

What is the rated output of your panel ?
Example:
The Kyocera "KD" 140 watt solar panels are by far our most popular panels for smaller systems & RV solar installations. They are available in junction box versions for hard-wiring, and in MC locking cable versions. All may be wired in parallel for use with standard charge controllers, or in series for MPPT type charge controllers. Specifications:
Max Rated Power (Pmax) 140 Watts Voltage at Max Power (Vmpp) 17.7 Volts Current at Max Power (Impp) 7.91 Amps Open Circuit Voltage (Voc) 22.1 Volts Short Circuit Current (Isc) 8.68 Amps Length x Width x Depth (inches) 59.06 x 26.3 x 1.8 Weight of Panel (Pounds) 28.4 Connector Cable Type MC4 Latching Cables


This panel is rated at 140 watts.
17.7 volts and 7.91 amps 17.7x7.91= 140.007

Check and see how close to this number a NEW panel is.
Check it each year.
This panel is warrantied to 25 years.
It should hit 90% of that number for 10 years.
It should hit 80% of that number for the remaining 15 years.

I have read others stating that their 30+ year old panels are still working.

That's a lot of questions at once. I'll let others chime in.
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Old 12-01-2014, 03:38 PM
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12vman Male 12vman is offline
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Quote:
Originally Posted by Lurch View Post
I have been using the same solar panels for the past 18 years. They appear to be working. How do you know when they go bad? Is it a sudden thing, or is it gradual? Will just one panel go bad, and not the others? If just one goes bad, will you notice the system being weaker? Will an individual voltage test of the panels tell you what you need to know?
(1) Is it a sudden thing, or is it gradual?

(2) If just one goes bad, will you notice the system being weaker?

(3) Will an individual voltage test of the panels tell you what you need to know?

1- Could be either, depending on what causes the failure. (Nearby Lighting Strike?) Mono Type panels are usually very dependable. They'll degrade for a year or so and mellow out. Poly Type panels could totally degrade over time, especially after the warranty period.

A friend of mine has a Mono Type panel (Arco) that's over 35 yrs. old and it still works almost as good as new. It has yellowed somewhat but it still puts out near the ratings..

2- Yep.. That would be a good guess. If you have a Trimetric unit installed, it will monitor the panel output and you can see if the output is lower than normal during similar conditions. I watch mine daily.. Trimetric 2020..

http://www.bogartengineering.com/products/TriMetric

3- A voltage test won't tell the truth. A load test to check the current output is the correct test. If you have a VOM that is rated more than the current output of each single panel, just short the panel with the meter in the D.C. current test mode and see how much current it's making.
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Old 12-01-2014, 04:29 PM
Lurch Male Lurch is offline
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Thanks for the help. Now I just need to wait a few months for the sun to come back.
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Old 12-03-2014, 08:01 AM
HuntingHawk HuntingHawk is offline
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I think most are 25-30 years for half life.
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Old 08-31-2015, 11:38 AM
TnAndy Male TnAndy is offline
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Quote:
Originally Posted by 12vman View Post
A friend of mine has a Mono Type panel (Arco) that's over 35 yrs. old and it still works almost as good as new. It has yellowed somewhat but it still puts out near the ratings..

I took a class to get NABCEP (National solar certification outfit) about 6 years ago. We looked and tested some mono Arco panels from the early 80's that would have been about 30 years old at that time. As you say, they looked crappy...they had yellowed some, some of the edges looked bad....but they still put out very nearly what they were originally rated at !

So my guess is 25 years is fairly conservative for most panels.

That said, I had a small 30w polycrystalline panel I bought from Northern Tool about 3 years ago, and used as a 12v battery trickle charger on a piece of equipment I don't use enough for the engine to keep the battery topped off.

The charge controller I had it run thru quit lighting up, (LED) and I assumed it went bad (cheapy controller)....so I replaced it, finding it still wouldn't charge. Got to checking, and the panel that SHOULD have been putting out 17-18v in good sun was only putting out 2 volts !

Replaced the panel, and all is well. SO, yes, they DO apparently go bad.
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