I have one of these 5W SOLAR PANELs (AMAZON) sitting inside the front windshield area plugged into a ALWAYS HOT 12VDC plug. It works at a reduced rate. Mine is a small watts one and I wish I had got one of the bigger ones...
It will only keep my battery topped off. You really need something around the 15-20 WATT level.
Similar to this GOOGLE image model..
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS