The transfer relay is wired in and working.

The transfer relay is wired in and working.
big load buss is now running through the transfer switch

Got the new transfer relay box mounted and wired in. This powers the big load manager buss in the main panel, from either the grid or the inverter, and can be remote controlled. It was a sunny day today, so I moved the hot water heater over the the new high load buss, and ran some hot water to see how the system would handle it.
It took almost 7KW, and well over 100Afrom the 48V system to run the big heater, but the solar input and the charge controllers were able to keep up and the heater cycled off after 10 minutes.
Will leave the hot water heater off all night, and recharge it once the batteries get recharged tomorrow, and see how much recovery is required. The system monitoring to best use the available power is going to be tricky to tweak due to the wide variability in solar input.