Maine Sail,
I used a standard 12 volt 100 watt panel (Solarland SOL50100 from eMarine).
Genasun's GV-BOOST (105-350W Solar Boost Charge Controller with MPPT) takes the output from the solar panel and outputs the nominal 24 vdc levels to properly charge the 24 volt bank. I found the Genasun site after reading your Compass Marine "How To" Articles.
While talking to the people there, they told me the controller was originally designed for golf carts. It is limited to 8A and programmed for one of these output voltages: 12/24/36/48V. Custom voltage programming is also available.
genasun.com/all-products/solar-charge-controllers/for-lead/gvb-8a-pb-solar-boost-controller/
