My big breaker panel is nearly empty, and my new breaker panel is nearly full, so after looking at all my options, I chose to cut the main buss bars in the big panel to break it into two separate panels in the same box.
Doing this live was not an option, so I turned off at the main breaker and the inverter, and rigged up a 48V battery from some prius subpacks, and powered my 1500 watt sine wave inverter, to power my cut off grinder to make the cuts, once they were cut, the bottom section of bus bars was easily removed, so the buss bars could be shortened. I don't want to be able to bridge the gap with a 240V breaker for safety reasons.
The photo shows how the two sections are coupled with a breaker on each with jumper wires for L1 and L2.
This is temporary. the final system will allow this second breaker to be powered buy either the grid, or the inverter, and the loads will be enabled or not with high power solid state relays.
Added a second current shunt so the combined solar charger output can be used to determine the battery capacity, and many other related functions. Needed to add a communication hub, and a flexnet DC battery monitor to gain the battery specific data needed to better evaluate the battery condition.