I contacted Sunrun to get a ballpark estimate on a solar system if I gave them all the design parameters - Size, kW/Hrs, location, racking type. I am shopping for homes, and some have solar and some don't so I need a rough estimate of what a system costs as a differential and if I want to add on.
I was told flat out that they will not do that. But they keep calling. And calling.
Estimation is the basics of engineering, contracting and supply.
If a contractor can't give a ballpark cost (+/- 25%) given the parameters, then they are looking to play you later on.