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Disconnected solar panel question

Subdood

Photon Wrangler
Joined
Mar 27, 2022
Messages
479
Location
NE Kentucky
I have a question about solar panel(s) that sit out in the sun but aren't connected to a charge controller or inverter. Say I have an array of panels hooked together, but not yet connected to anything and not generating any power. Is there a potential danger of any of the panels being damaged being exposed to sunlight? Just because there's no current flowing, there's still PV cells still doing their thing in the sun.

I ask this because a few months ago, I bought a 200W Newpowa panel to run with my Ecoflow River Pro. I ran it a few days in the sun, and I never seemed to get more than 180W. There were times it sat out in the sun for a few hours a day not hooked up to the Ecoflow. A few days later I was cleaning the panel, and saw what looked like a partially burned cell about the size of a quarter. The panel didn't seem to put out more than about 140W after that. Whether the burned spot was there the whole time or caused the loss in power, I don't know.

So I contacted Newpowa and they said since the panel wasn't hooked up and charging the generator, then it could damage a cell since there's still PV potential being generated, despite no current flowing. I took pictures of the burned area and sent them pics of that along with the serial number. I disagreed with their explanation. But, after exchanging a few emails with them, they said that they would replace the panel, but I'd have to ship it back to them, at their expense. Thankfully I kept the box, so I repacked it and sent it back to them via FedEx. A couple weeks later I got a new panel, and it seemed to work fine, at times I'd get about 190W. After inspecting the panel more, to my surprise I discovered that it was a 210W panel. I emailed them and told them about this, and they said they didn't have any of the 200W panels left,, so they upgraded me with a better one. So that was nice of them to do that. So kudos to Newpowa for that.

But anyway, I thought their answer about the panel being disconnected sitting in the sun would cause damage was bogus. I know system arrays are built and obviously aren't hooked up to anything at the beginning, and I doubt they cover the panels to protect them from such damage. What say y'all? I'm about to build my array, and am curious to the answer.
 
Your panel power raiting sold to you is based off of STC. For example, the new 210W one. Here is the data sheet.
1662253286186.png

Note the line at the bottom where they hide the test. This is in Standard Test Conditions. Usually you will only get about 800W/m2 in real work situations (PTC I believe). I usually figure what ever their rated wattage is and subtract 20% unless the PTC lists otherwise. Temps have a factor as well as angle. I don't think there would be an issue with it being disconnected other than sitting flat on the ground and heating up too much.
 
Basically, no damage other than normal degradation from solar exposure. Protect the open mc4 ends from moisture.
 
Heat could always come from the outside, but the only way the cell could heat from its own ‘potential’ is if current actually flowed. The only way current could flow in a panel with disconnected open circuit ends, is an internal short which would be a manufacturing defect.

Sounds like it worked out ok. I don’t place much of a value judgment on any company making at least a token effort to avoid giving money away even when things are their fault, because a lot of times the first point of contact for a warranty claim is someone that can lose their job for not at least TRYING to scare the customer off before upholding the warranty obligations. If that person gives you a panel without putting up a fight, they basically just tripled their cost to the employer because that transaction probably cost twice what they get paid in a day.. and they still got paid. That’s if they only do it ONCE in a day! Any form of ‘claims agent’ their job first and foremost is to run interference between the customer and the company accounts.

If you can settle it up in a few emails back and forth and they paid return shipping id put that as above average in 2022..
 
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Thanks for all the replies. I agree that a panel(s) not connected shouldn't be damaged simply by sitting out in the sun. I tried to explain that to them, but they didn't agree. But, to their credit, they did replace the panel at no cost to me.
 
If you can settle it up in a few emails back and forth and they paid return shipping id put that as above average in 2022..
I think they knew their explanation was bogus, and I explained why I thought so, so that's why they did what they did, which was fine by me. I still have the panel, and it works fine, on some days I was able to get about 195W out of it, which is +90%, which is very good.
 
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