NFPA 70E Table 130.7(C)(15)(b) for DC systems only goes to 600V. What is everyone doing for battery banks greater than 600V? We have had inquiries on arc flash for battery banks of 900V and 1500V.

I am thinking the only way is to use the Maximum Power Method as described in Annex D.5 but that has a limit of 1000V so for 1500V that would not work.

Suggestions?

Not an answer, but a comment about battery voltages of 500VDC and greater…
Laboratory testing by Quebec Hydro in 2019 suggests that 500VDC batteries may have arc times exceeding 2-seconds. Their testing was designed to terminate after 2-seconds. All their 500VDC tests went the full 2-seconds and the arc was extinguished by the test equipment.
This research was published in the proceedings for the 2020 IEEE Electrical Safety Workshop.

A midpoint current limiting fuse may be in order for battery voltages of 500VDC and greater to limit arc flash incident energies to reasonable levels.

The 2 second limit was never intended to be an arcing limit, it represents an exposure limit for someone who is moving away. With no zero crossing, these arcs are rarely self extinguishing.