I use a
Amazon cheap
Newpowa 9BB 30W 12V Solar Panel High-Efficiency Monocrystalline 12V PV Module Designed for 12V Off Grid System, Charge Your 12V Battery of RV, Boat, Camper, Trailer, Gate Opener
And a
WERCHTAY 60A MPPT Solar Charge Controller 12v/24v Current Auto Focus MPPT Tracking Charge with LCD Display Dual USB Solar Regulator Charge Controller Multiple Load Control Modes
Works just fine sitting in the field and keeping battery charged for weeks sometimes.
I put a switch on solar wires so I could turn off power when moving it around etc.
plenty of options on all the online sites.
