Wire might be worth $2 to $2.5
Current Buying and Selling Prices: Earthworks Recycling, Inc -- Spokane, WA
Might depend on where you live.
I'm pretty sure that copper wire can't be used in a solar-thermal collector.
At least no obvious method comes to mind..
Depending on the type of wire and it's insulation, it might be useful for solar PV battery charging setups.
It might be wise to keep a low profile about your copper..
There seems to be something in oxycodone that allows
addicted copper thieves to smell copper at long distances.