Since you are DC coupled, the settings get a bit interesting. I have read up a bit on it since I am hoping to add some DC panels and a Schneider MPPT 60-150 to my system.
As I understand it, the XW-Pro inverter will start using battery power as needed to meet the power goals set in the Grid Support or Generator Support menus. It will be able to run until the battery is depleted to your minimum voltage or state of charge settings. In my case right now, the only charge source is the XW-Pro inverter, and that causes a few problems with their software. Grid Support and Sell to Grid can only work when the battery is 0.5 volts above the Recharge Volts in the XW-Pro. That makes it so I can't get it to go back into charge mode on it's own. But that is not a problem when your charge is coming from the MPPT controller.
You can do a few different things in the MPPT to get around this problem. The first one is that you can set the Recharge Volts in the MPPT to a different higher value than it is set in the XW-Pro. So the XW can run the battery down to where the MPPT will go back into bulk charge mode. But you can also do one better. Set the MPPT to also use "Float Charge". Now we don't really want to keep our Lithium batteries on float charge, it's not good for the batteries, but by changing the settings, we can make it do something very cool. Once the battery is fully charge after the bulk and absorb charge modes are done, we do want the charge current to stop. So we set the MPPT float voltage about 0.5 volts below the voltage the battery rests to when the absorb charge ends. Let's say we have very little load on the output of the XW. The solar power from the MPPT will top up the batteries, and then shut down. But now the solar energy hitting the panels is just not being used. That's not good. But where is it going to go? Unless you turn on a dump load, this is all we can do. We don't want to over charge the batteries. Since the battery is 0.5 volts above the float voltage, the MPPT does drop to zero current, so we have "no float" current. But now we do put a load on the XW output. Now the battery voltage starts to come down. After it drops that 0.5 volts, then the MPPT will start using solar power again to keep the battery at this "fake float voltage" and it will ramp it's current up to hold the battery at this voltage. We can set the maximum float current up quite high to use as much solar as we can to keep running the loads until the sun goes down. After sunset, the MPPT shuts off again as there is not solar coming in. The XW will run on the batteries and bring the voltage down to it's low voltage cutoff, or until the sun comes up the next day. As long as the battery went below the MPPT controllers "Recharge Volts" setting, the MPPT will go right back into Bulk Charge when the sun comes up.
Since the MPPT and the XW inverter are separate devices, the XW can be inverting from the DC buss and powering loads while the MPPT is taking the solar power and putting it onto the DC buss. As long as the solar power is greater than the power the XW is pulling, the battery will be charging with the difference. If solar falls short, it will be discharging the battery.
In my case, I will have the MPPT 60/150 set to it's maximum 60 amps. My planned DC solar will top out at under 3,000 watts. That just about maxes out the 60 amp MPPT controller at 48 volts. So any power that the inverter needs will come out of the charge rate. If I have no load, the 60 amp charge rate is no problem for my battery bank. But if this was a system with a lot more DC solar, and batteries like flooded lead acid, the charge current may need to be limited. From looking at the settings, I can't tell if the Schneider system is smart enough the know it could supply the battery charge current PLUS and current being used by the inverter. For example, you have 8,000 watts of solar to a pair of MPPT 100/600 charge controllers. At solar noon, that could exceed 150 amps amps of output from the MPPT's, but the battery bank might only be able to take 80 amps. But the XW inverter is pulling 4,000 watts to run the refrigerator and the mini split A/C. If the current limit was set to just the safe 80 amps to the batteries, then all of the solar would now just be going to the inverter, and the batteries would not be charging at all, even though, we do actually have plenty of solar to get some charging even while running the loads. Does the Schneider Batt Mon tell the Schneider MPPT's what the true charge current really is?
