The General Specialties UPM 6X model will be a good Top-of-Pole Mount for an approximately 840W system.
It will fit 6 Size A modules or 4 Size B or size C modules (see category descriptions below), all in a 1 column format. Note that this UPM 6X is not available for Size D modules (the big 72 cell panels).
This mount is built for a 5" post--Schedule 40 or 80.
Module Category Descriptions:
