yes maybe i will have to parallel them up, I'm a bit reluctant as the boat has run for 25 years on this arrangement, the current batteries are six years old and still holding a full charge.
I suspected the diodes within the unit would restrict any back feed damage to the controller when the "both" switch were engaged but not too sure ( it works fine with my onboard Sterling charging system when i run it off the generator or occasionally plug in to England). likewise with the alternater from the engine, which also has an in line controller - seems to work ok
Problem with solar panels is they are constant, I would hate to come home to find a melted box and an engine room full of smoke!
thanks for all your input.
like your view thouhg smiley pete - your link is the very item.