Jeff, In my limited knowledge of this issue, there is no doubt DC arcs have the capacity to burn and are difficult to extinguish, and good wiring practices are essential at these elevated voltages. However, you need to distinguish between high temperature arcs which can burn, and Arc-Flash risks which require special PPE and procedures. In order for the there to be a serious risk of Arc-Flash, there has to be both a high voltage such as 480V and a very high source current, in the order of 65,000 Symmetrical Amperes, such as you find near a HT/LT transformer. The extremely high current is what creates the explosive heating of the air. Solar PV, being current limited, has high enough DC voltages but does not have anywhere near the current capacity and cannot cause arc flash.
Chris
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