Appreciate the question! The coordination is similar to what a whole-home battery might be doing for you, depending on how you configure it: Timing charging to follow real-time solar production, energy arbitrage to shift home usage to times of day when electricity is cheaper (e.g. TOU rates, big in my neck of the woods in California), "storm mode" to charge up automatically when severe weather alerts are issued, and eventually things like Demand Response for grid services which you can get paid from if you opt into. Beyond the battery control stuff, locally sharing energy data across the batteries across your home can help build a model of energy usage to help make sense of your usage, look out for anomalies in your home wiring, and more -- And doing this with a local connection just means it can be a more reliable, more resilient system, even providing this sort of value when internet drops out

The simple case I can think of is priority charging, with total load limiting. Since solar supply is variable you want to avoid drawing from the grid if possible, and you want batteries attached to things that will draw the most expensive power (by typical usage time) to fill first.