On Amazon. Haofy 40W 18V Monocrystalline Silicon Flexible Solar Panel, Waterproof with 20A Outdoor Adjustable Solar Charge Controller High Efficiency Module Photovoltaic Power Supply for RV, Boat, Camper
Brand: Haofy
$36.99
----------another Amazon vendor sells the same unit but without the controller for the same price, so you may as well order with controller. It has a setting for the newer Lithium phosphate batteries. This solar panel did a good job keeping my batteries charged on my other boat which I sold so I ordered one for my new boat. I don't know how long it will last, but for the price, hey yeah. The dimensions are just 11" by 11".