The PV Installation Professional (PVIP), PV Design Specialist (PVDS), PV Installer Specialist (PVIS), PV Commissioning & Maintenance Specialist (PVCMS) and PV System Inspector (PVSI) certification exams are all using the 2017 NEC.
The new Energy Storage Installation Professional (ESIP) certification exam is using the 2020 NEC.
The NEC stays mostly the same as far as the exams go. There are probably one to zero questions where the version of the NEC would make a difference. The exam committees do not try and trick people based on versions of the exam.
In our NABCEP prep courses, we typically keep 2 versions of the NEC, so students can balance the version being used on their NABCEP exam as well as what may be adopted in their local areas. It is real life that there are so many different versions of the NEC that we are dealing with. It is helpful to remember that the NEC is mostly the same year to year, decade to decade. Most of the changes do not change the way we do things, it is primarily organizational, such as moving something to a different place or renumbering something.