Can sch 80 pvc be used under 600 volts between conductors

Why not use UL approved NMT. As cheap as PVC.

It is on a solar project and the have is already installed and inspector turned down, as 2005 code say 300 volts or less I found ul 5 listing that states 600 volts or less using pvc.

Ask him why he turned it down? What are you running in the conduit? Possibly because PVC is ASTM but not UL approved and is not permitted for direct solar load. NMT is basically the same material but is UL approved and can be sunlight resistant.

Are you running AC or DC through it? And do you know what brand pipe it is? Where are you? And why is the AHJ quoting code from 2005?