What is the official NCARB stance of PV Panel Angles?

The old think was that they are mounted at the same angle as Latitude to maximize energy output.

The New Think is that panels should be mounted horizontal like a flat roof b/c this has been found to have a higher energy output by FAIA architects who specialize in BIPV stuff. (this may even be in the latest IBC code cycles too)

so which one is the 'correct' answer on the ARE?