Rich Palmisano
Just a fiddler at heart...
Apparently the QO and QOB are DC rated for 48 Volts.
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In my circuit breaker panel/box, I have one 50 amp main, one 30 amp 240vac (for air conditioner), and a bunch of 15amp and 20 amp breakers for the house. All are from Square D. After I retired, I worked part-time for a hardware store in the electrical department. I could be wrong since it been over 15 years since I worked in that store, but I don't recall Square D making a distinction between AC and DC.
I too have a lot to learn as I'm new to the Solar stuff and working with DC components.