'20 Forester 3011DS
Is it possible to leave a solar panel on the inside plugged into a cigarette lighter? Wanted to add a little charge to the engine battery while in storage.
You will still want a small charger controller or it's possible you will bleed more energy than you gain. You will also want it wired to always hot as many vehicles will turn off power points like power sockets after a while.
Avoid anything with a light if you can. It will drain more overnight than it provides.
Not sure how beneficial small ones are as it depends on the vehicle and what your idle current draw may be and if you can offset it. Maybe best to meter it out to figure it out.