When a customer has a solar heating system installed in their home they expect (and rightfully so) that their energy bill will drop pretty significantly. When a customer doesn’t see as much of a drop as they expect the question is why. One of the things that I encourage solar contractors to do is calibrate the expectations of their customers. Let them know what they should expect from their system. The best way to do that is to provide a simulation report . With this tool they can easily see what to expect from the system. Things keeps everybody on the same page about what the system should be producing.