Junk yards like to say that all cars run on used parts. It is true. The same is true of solar installations. There’s a solar farm being built just up the road and there are 180,000 panels sitting in piles in the field. They are soaking up dust, dirt, rain and humidity while waiting to be mounted. And they’ll work.
What about panels that have been installed and running for 5 years? They are likely to have a slightly reduced output, but they are also very likely to be pretty cheap, compared to new ones. Which is the better deal?
Personally, I have bought new, latest, greatest panels for my boat projects to get the most watts in the limited space available. For my house, though, I have hundreds of used, sometimes abused panels. The last panels I installed were on my ground mount. Not sure how old they are, but they were in service, out in the elements since 2015, and they work great Others, the ones that were literally thrown off the roof when taken out of service, are mostly still running fine.
Good news for folks considering buying used modules, a recent report says that panels made a few years ago were made differently and do not degrade as quickly as the newer panels. Don’t worry, neither is likely to be a problem. The report says the big difference is in the layer of clear sticky stuff between the glass and the silicon. Just like the plastic headlights on cars, enough time in the sun and they start to discolor. The layer in a panel is so thin that you just don’t notice it. Frankly, the solar cells don’t notice it much, either.
After a dry spell, John is once again finding scads of used panels and new-old-stock surplus. Don’t be afraid of them. They’re good, cheap watts.