Orrrrrrrrrrrrrrrrrrrrrrrrr,
You can use ANY panel of around 30 watts, and a DC to DC converter like the 600 watt found on Amazon. 56.0 volts is nominal bulk charge limit on a 24 cell system which is 8 volts higher than 2.0 volt X 24 = 48. Split the difference, add 4 volts and 52 volts will be your float. Therefore you will be boosting from 12 volts minimum to 52. This is well within the design specifications of the booster.
I cannot imagine a high voltage panel array for as little money as the most economical 30 watt lower voltage panel you can find + a twenty eight dollar booster. The boosters are rugged. If you want it bulletproof play a 12 volt computer fan on the booster fins which would be wired directly to the panel.
This setup is no more difficult or complicated than setting up your idea of panels plus a controller. Strike that. This is a single panel affair I am suggesting - considerably less work. The booster positively disconnects the panel when there is no voltage on the booster input.
Remember 52, the number of cards in a deck.
Piece of cake...
