I'd like to supplement my existing electric hot water heating system with a rooftop solar system in order to reduce electrical use/cost. I've been searching the net for "How-To's", but haven't found much of anything useful in terms of understanding design. Everything I've found are advertisements for systems and they don't explain whether they are independent or not. What are some good sources for learning about these things. I need to understand if I can connect a rooftop box-type heater into the existing electric heater and how that is done mechanically. Also, should these systems be drained in wintertime? I live in Virginia Beach and have a porch roof attached to the garage where the heater is located. The porch faces southeast and gets no shade. It has a new flat roof with rubber membrane. Like most, I'd like to keep installation costs down, but I will hire a plumber and electrician if needed.