I have never seen one quite like this. It was built by a local PV installer to monitor a new the Lithium-iron battery bank. It also opens a contactor located in the main DC panel and cuts the PV output to the batteries when they are full. I'm not quite sure <b><i>why</i></b> they did this, as the system uses a Schneider XW inverter, PV controller and power panel, all of which can be easily programmed for LiPO4 battery chemistry...
We are going to decommission this this soon, and it will be interesting to tear into it and see what made it tick!