There's only two options   Type of Asset - F  rental furnishings    or  I - Rental Real Estate       well maybe three because you could choose   O - other 

So if the neighbor came over and said "hey I really like your solar system can I buy it?"    could it be removed and sold without tearing into the property?   If no - then it is part of the real estate.   Doesn't a solar system require lots of "plumbing" installation.

Qualifying solar energy equipment is eligible for a cost recovery period of five years. See link:

https://www.seia.org/initiatives/depreciation-solar-energy-property-macrs

They are solar panels so no plumbing installation.

What I meant by "plumbing"  is the connection from solar panels to what is being powered by them.