I have a couple of these 10-watt solar panels and I have one sitting in my truck dash area and always plugged into an always "hot" 12V connector. It definitely makes a big difference on my truck start battery during the winter months...
I built up a new battery bank here recently and the Torklift battery case came with one of these 10W-solar panels mounted on one end of the slide off lid. I purchased a second 10WATT Solar Panel to add to the other end of the slide off top. My battery bank consists of two 6V Battery groups and these two 10 Watt solar panels does very well being used as a trickle charge for the two 6V battery groups...
Roy Ken