In short - UL Listing
While I am in an area that doesn't require any inspections/permits, I am funding the initial install with a low interest rate DEQ loan, and the loan terms required a final inspection when complete. When applying I had to provide a list of components to be used and they wanted the components to be UL listed. The 250/100s are listed, the RS450s are not. Down the road future expansions will likely leverage the RS450/200(s).