I started getting excited as he pulled out a 2.5 amp panel on a nice long extension cord and pointed it at the sun. Of course I was all over him with questions. He showed me how the newer designs could handle a little shade on part of it without shutting the whole panel down as the older ones would. The newer ones have a bunch of smaller cells all in parallel with diodes to protect any shaded cells from drawing power from the sunlit ones. The current production goes down as it's shaded, but that's about all.
Heat is something to think about when using a panel.
It's best to keep it from laying flat because of the heat build-up. It reduces the efficiency of the panel. When camping a simple dowel rod to prop it up is all that's needed - and that lets you adjust the angle to the sun. He proceeded to show me a meter panel he had built using a couple of digital volt meters. He had them wired up to display the battery voltage and the current to AND from the battery.