Which means the old panels should be reused instead of recycling. Perhaps that's the point. Clean the protective layers and resell on used market.
•Used solar panels are off-spec and can't be teamed with other used solar panels properly. They become like two drunks trying to help each other down the street.
•Even used solar panels need mounting/racking hardware.
•Even used solar panels need inverters and wiring (frequently in values that are out of production).
•Used solar panels are a b*@#% to ship.
The glass, if intact, is the most valuable part of the solar panel for recycling purposes. This is followed closely by the aluminum frame.
The EVA (clear rubber) that encases the solar panels is garbage by the time the panel gets recycled. This is the part that turns brown and lets in moisture. I imagine incineration is the best path forward for this stuff, because after 30 years of cross-linking in the sun, it's not going to melt into a liquid.
The solar cells themselves are so enmeshed with the EVA that they turn into inchlong irregular shards attached to tabbing. There's no realistic hope for getting a commercial-grade panel out of them, even if you melt them down.
The tabbing is a valuable mix of tin, copper, and silver, as is the metallization on some cells, though you'd have to be talking tons of crushed cells to get a pound each of the metals. This should be a straightforward matter of crush and dissolve in chemicals, then throwing the stripped silicon into a smelter somewhere.
The "J-box" doesn't count for a lot of weight and is probably too old-fashioned to reuse, even if the plastic hadn't broken down and the contacts hadn't corroded. Best off cooking off the plastic and remelting the copper/tin metal portions.
You might find yourself in a position to say, hey, I'd gladly accept a used 3 ft x 5 ft solar panel that worked 50% as good as new, and was ugly. I doubt you would be in the position to take on 100 more, especially not being able to team them together.
It's not unusual to see brand-spanking-new panels at prices near $0.50/W. Shipping is starting to dominate the cost of panels, used or new.
And yes shipping will be truly a pain in the ass. A brand new pallet of 20 or 22 panels with the special plastic protectors in place, and wrapped up with plastic, is easy to ship. Individual loose panels are difficult to transport loose without damaging them, and labor intensive to move around.
One of the things you can do with used panels is re-use them for off grid applications. There are off grid PV charge controllers now (Schneider, others) which support up to either 600V or 1000VDC on the PV input side, and up to 4800W of panels per charge controller. You can build strings that are basically all of the panels in series together, simplifying the wiring, assuming that the panels are new enough to be also rated for 600V (US) or 1000V (EU) spec, mostly intended for feeding big inverters.
I wouldn't really say that shipping dominates the cost just yet. I recently bought a pallet load of high-efficiency monocrystalline panels (72-cell, 360W) at around $0.62/watt. The shipping for the pallet was about $350. The panels themselves were about $4500 FOB.