Why shouldn’t solar panels be tested before acceptance?

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ACH

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I subcontracted a residential solar installation. I have never used solar before. I was expecting the new panels to be tested before accepting the installation. The solar contractor told me that testing the panels was never done and is not necessary. Is this correct?
 
ACH said:
I subcontracted a residential solar installation. I have never used solar before. I was expecting the new panels to be tested before accepting the installation. The solar contractor told me that testing the panels was never done and is not necessary. Is this correct?
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He is correct that most if not all solar contractors test the whole system once it is installed rather than the individual modules before installation. This is because the "out of the box" failure rate for solar modules is virtually zero since the manufacturers do extensive testing of their products before they are sold. There are occasionally problems with completed systems but they are nearly always because of something other than the modules themselves.
 
About the only thing that could cause a significant panel test failure on arrival would be damage in shipping. And that would normally be visible, without the need for testing.
 
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ggunn said:
He is correct that most if not all solar contractors test the whole system once it is installed rather than the individual modules before installation. This is because the "out of the box" failure rate for solar modules is virtually zero since the manufacturers do extensive testing of their products before they are sold. There are occasionally problems with completed systems but they are nearly always because of something other than the modules themselves.
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The growth in "solar portals" also means that installers and customers are able to see what the system is doing. Failures usually show up the first clear sky day after an install, if they are going to happen.
 
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My understanding is that many PV installers include a performance warranty; in other words guaranteeing that the system will produce what they said it would. In which case the system is being 'tested' on a continuous basis.

-Jon
 
I work for a pv installation company and we turn on the system and make sure that all of the panels and microinverters or optimizers are functioning properly before we disable production and wait for the inspection.
 
In my infancy as a PV person, the company I worked for used to test each module for Voc and Isc before installation. It was a PITA; I do not remember any module ever failing and I'm pretty sure no one does that any more.
 
jaggedben said:
A module manufacturer rep told me today that their warranty replacement rate is 70 out of one million.
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It was a lot higher 20 years ago. The manufacturing volumes were also a lot lower, and volume is one of the things that helps quality.
 
We have been required to test large commercial and utility systems by the bank, but not each individual panel, at the string or system level. It used to be more but much less now, only large ground mount arrays.

On a residential or systems attached to a structure though there is nearly no purpose at all though because with module level rapid shutdown, comes the ability to monitor the basic functionality of each module, and it if functions at all it likely functions close enough to spec that the cost to test is not justified.
 
ggunn said:
It's not all that hard; you'll just need a DVM with clamp ammeter and a pyranometer.
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Don't forget a load.

The monitoring software I wrote 12 years ago used a pyro, panel temp sensor, geographic location, array orientation, and the current time to estimate production. As long as it was in 1-2% (assuming a clean array) I was happy. Production estimates in situ are easy with the proper data.
 
jaggedben said:
I guess I read something into the comments above that wasn't there, but my supposition is that with our projects the client wouldn't think of asking until after installation.
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I don't know why a client would ask to have individual panels tested after installation. The initial power output obviously should be compared to what's expected, subject to things like weather (cloud cover) and time of year.
 
tallgirl said:
Don't forget a load.
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For a quick and dirty test you don't need a load. Check Voc with leads disconnected with a voltmeter, then short the leads and measure Isc with a clamp ammeter adjusted for insolation from a pyranometer reading in the same orientation. It's not all that accurate or comprehensive but it's good enough to find a faulty module, which is, as we have discussed, very unlikely.
 
jaggedben said:
What kind of testing do you mean exactly? Testing each panel in a specific way, or testing broadly for the installed system functioning?
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I was just thinking that if I am purchasing a 400W panel it should put out 400W or close to 400W.
It appears that this is not normally done so my expectations are probably unreasonable.
 
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