2005 Horizon 40AD solar upgrade

I am still not sure about the current rating of my existing charge controller. from what I can find though, I think it is unlikely to be anything that will work with my upgrade. It is a multipurpose unit made by Ventline and was probably sold by the thousands capable of being nothing more that a bell or a whistle that would cause a prospective sucker, I mean buyer (like me) to be impressed and just have to have it.

The unit controlled everything from tank levels and battery condition monitors to pump and hot water controls, the solar controller being only one small part. My issue now is being able to strip it from the other systems so I can incorporate a separate controller and leave everything else that the unit does in a working state. If I manage that, I may consider running something from the new controller unit to the charge LED in the old one just so it still lights up when charging. I would have added some pictures of my unit as well as a pdf I found online with some limited information but the add image feature here seems a bit beyond my capabilities. The part number for my multipurpose control board is Ventline L5130-02

Thanks again for the help folks!