Plug in Portable Solar Panel

Yep, we have a 120w fold out solar panel [ has it's own reg] that plugs into an Anderson plug with the required cables to the batteries.
Handy when 1 or more [of the only 3 panels] is in the shade, also use it to charge the 3rd battery [a 105ah] in the tug that runs the 55l Evercool 12/24v fridge , the 2nd tug battery [105ah flooded] is the reserve and charged by the alternator [or panel if need be].

This is an interesting thread because there are now good campsites under some "regulations" which insist NO gennys. e.g. Mornington Station, W.A. This great place has a large camping section almost covered with large trees. Sunshine is able to penetrate very few areas and for very limited times. There is so much to see and do on this huge property e.g. birding, canoeing and swimming that a prolonged stay is desired. Whilst there last year I noticed many campers using these flexible solar panels. I have an Anderson plug on the BT. Not entirely sure if it has a diode which would not allow current to flow into the BT battery bank. I have a vague idea it is for surplus power from the BT solar panels to top-up the L/C batteries or is it for cloudy days when travelling and excess power is fed from the L/C? Electricity puzzles me mostly. Any sparkies out there shed any light on this. May be of interest to others too. cheers.

Could you please tell me the cost if these flexible panels? Thanks, Rod