We used a stand-off bracket from Sailrite. It is a clamshell that goes around the existing dodger frame with a 2" post welded to it (they sell them for add-on handrail installation) and a socket for a 1" SS tube. Buy the tube in the length you need, and mount the panel to the tube using aluminum unistrut (see McMasterCarr) and 3/4" SS pipe unistrut clamps. The nice thing is that you can tilt the panel to the sun about 15 degrees. I have some pix:
There are places online that sell kits to do the same thing, but it's much more fun (and much less expensive) to reinvent the wheel!!