Site Controller

A site controller is the industrial computer at a solar or storage site that runs the energy management system and power plant controller locally, so dispatch continues when the cloud connection drops.

The controller polls the devices on site over Modbus or DNP3, runs the dispatch algorithms and grid code functions on a fixed cycle, writes setpoints to the inverters, and logs every reading and command. It syncs to a cloud service for dashboards, fleet views, and reporting, but no setpoint depends on that link. A site controller is the reason a storage EMS is described as edge software rather than cloud software.

Also called: Edge controller, Local controller, EMS appliance