I was wondering what to look for in used panels to see if they would work into a system or not. I got to thinking about it because there are a lot of places in my area that appear to have had solar systems. One place that comes to mind is a set of 4 large panels pointed south with a big beautiful blue spruce tree providing them shade for the bulk of the day literally less than 3' south of here. I figure in the down economy we are in, I could probably offer to pay them a little to remove these eyesores from their property and the short sighted ones would gladly accept. However I don't know much of anything about solar panels, technology advances or how to ascertain their serviceability. I'm a younger guy and buying new is probably not in my financial realm of possibilities. I am an elbow grease kind of guy and have a broad (albeit shallow) knowledge of electricity and most things mechanical, and I believe I could piece together a decent system off old used components. However their would be very little tolerance from the wife for buying useless panels. Long question short, how can you tell if old panels are worth a darn?