solar panels are a system in their own right. The energy produced is used for whatever you are using at time it is being produced. A specific Hot Water system generally requires purchase of a new hot water tank and heat transfer system for the water as the water produced in such a system is at a higher temperature than other systems. If your existing hot water tank is fairly old it may be more advantageous to go for a new hot water system. I have gone for panels to use for whatever as hot water is not the greater portion of my bill and I would only consider the discreet hot water system if my hot water tank departed this life. Hope this sheds a little light on the subject.
