I have two solar panels mounted on my railings. I replaced the wires with 1" tubing and various Ts and +s that I got at a boat store. The railings are mounted on pieces of aluminum and have white plastic clamps designed to use on this tubing. The panels mount to the top rail and I support them with props made of 1" x 4" cedar with a 45 degree angle at one end and a half circle at the other end to sit on the lower rail. I also have light line to hold them in place.
Had them for 20,000 miles and only one serious problem. We were knocked down and I had pivotted the panels down against the railings before hand. I also tied them down which might have been a mistake. When we were laid over a wall of water came from the other side of the boat, over the cockpit and hit one of the panels. It is was not tied it might have done better but it was smashed outward (the safety glass top was all bent and shattered).
We have two 85 w panels and it handles the refrigeration in tropical conditions without a probem (if it is sunny!)
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.