One central controller for multiple PV inverters in Poland

Polish distribution system operators (DSOs) are placing increasingly strict requirements on the control of PV plants. When a plant contains several inverters, the DSO may need to limit or shut down the complete installation as one system.

SmartgridOne supports this integrator function by forming the central connection between the DSO and all participating inverters. In this context, an integrator is the plant controller or gateway that translates one external command into the correct command for every connected inverter.

How the architecture works

The DSO does not have to address each inverter separately. It sends one command to SmartgridOne, which applies the appropriate command to every selected inverter. This enables the complete PV plant to be:

• limited to a common power level;
• shut down completely;
• released back to normal operation;
• monitored centrally; and
• controlled against one shared setpoint.

Support for mixed inverter fleets

PV plants do not always consist of identical inverters. Extensions in particular may combine different brands, models, nominal powers, and communication interfaces.

SmartgridOne can bring several devices and protocols together within one installation. Each inverter remains individually addressable by the controller, while the DSO sees and controls a single coordinated plant.

This architecture is suitable for:

• installations with two or more inverters;
• inverters using different Modbus addresses;
• combinations of different manufacturers;
• existing plants that are expanded later; and
• hybrid sites with PV, battery storage, and other controllable equipment.

Communication through Modbus and SunSpec

For multi-inverter plants, Polish DSOs commonly request one shared controller. Communication with that controller is often implemented through RS485 and the SunSpec protocol.

SmartgridOne acts as the central gateway: it receives the external command and converts it into the correct instructions for the connected inverters. Depending on the project, the connection may use RS485, Ethernet, or an appropriate protocol converter.

The exact interface, SunSpec configuration, command set, scaling, and feedback requirements must follow the technical specification of the DSO involved in the project.

Older inverters without external control

Not every inverter provides Modbus or another usable external-control protocol. Such devices can still be included in some projects by letting SmartgridOne operate an external relay or contactor.

Safe behaviour if communication is lost

An integrator design must define what happens when communication with the DSO or a controlled device is interrupted. SmartgridOne supports watchdog and fallback functions so that an agreed safe state can be applied when no valid control command is received within a configured time.

Depending on the DSO's requirements, the plant can be configured to:

• fall back to a predefined power level;
• reduce production to zero;
• shut down the inverters; or
• be physically disconnected through a contactor.

The selected fail-safe behaviour must be verified during engineering and tested as part of commissioning.

Project-specific engineering

Because requirements vary by Polish DSO and connection type, Eniris reviews each integrator solution individually. The review covers at least:

• the DSO responsible for the grid connection;
• the inverter manufacturers, models, firmware versions, and quantities;
• the required SunSpec commands and feedback values;
• the necessary RS485, Ethernet, and network connections;
• the timeout and required behaviour after communication loss;
• whether an external relay or contactor is needed; and
• the acceptance tests that must be completed during commissioning.

This creates one central, coordinated, and future-ready control system for the complete PV plant.

Prepare your project

To assess a multi-inverter project, provide Eniris with:

1. the electrical single-line diagram;
2. the make, exact model, firmware version, and nominal power of every inverter;
3. the local DSO's current interface and control specification; and
4. the planned communication path, network details, and requested commissioning date.

Submit the available technical information through the Eniris integration request form. Eniris will determine the appropriate SmartgridOne configuration and identify any project-specific engineering or hardware requirements.