If the ground wire is attached from the combiner box to the grounding rod, do the panels still need to be grounded?
If the panels are grounded to the same rod, I suppose you do not need to add a second grounding. In the case of an electrical storm, the grounding of the combiner panel is of the upmost importance.
Can I use different wattage panels to connect to this box?
No, only panels with the same voltage and wattage can be connected to the same box.
Under what circumstances is this used?
It is mainly used in home kits to combine up to 5 solar panel inputs into one single output, and it can be installed either indoor or outdoor.
Does a surge protective device have to be installed?
Yes, we suggested installing it in order to avoid device damage caused by lightning.