Short Definition

An energy management system (EMS) optimises and controls energy flows between PV systems, battery energy storage systems (BESS), loads, generators, and the grid connection point. A supervisory control and data acquisition (SCADA) system primarily serves the centralised monitoring, visualisation, and operation of technical assets. Both systems process operational data and can transmit setpoints or commands, but they have different functional priorities.

EMS and SCADA at a Glance

• An EMS calculates operational setpoints for energy assets based on measurements, operating limits, forecasts, and defined objectives.
• A SCADA system provides a central overview of plant conditions, manages alarms, and enables the monitoring and operation of technical processes.
• Both systems can be used in parallel and may include functions associated with the other system. The exact distinction is therefore project-specific.

What Is the Difference Between an EMS and a SCADA System?

The main difference lies in their respective primary functions. An EMS processes energy-related data and uses it to calculate operational setpoints. This data may include current power at the grid connection point, site consumption, PV generation, BESS state of charge, technical power limits, forecasts, electricity prices, or external schedules. Based on this information, the EMS decides, for example, whether a BESS should be charged or discharged, PV output should be limited, or a flexible load should be activated. A SCADA system focuses on the higher-level monitoring and operation of a technical plant. It collects measurements and status information, visualises processes, stores historical data, and reports faults. Operating commands and setpoints can be transmitted via the SCADA system to local control systems, remote terminal units (RTUs), programmable logic controllers (PLCs), or other plant controllers.

EMS

• Optimises energy flows according to technical and, where applicable, energy market objectives
• Calculates setpoints based on defined operating strategies and operating limits
• Considers factors such as forecasts, electricity prices, states of charge, backup reserves, and grid connection limits
• Automatically calculates and transmits setpoints for energy assets
• Typical applications include peak shaving, self-consumption optimisation, and BESS dispatch

SCADA

• Monitors and visualises plant operation
• Enables operator actions and transmits commands or setpoints to subordinate control systems
• Primarily processes measurements, status information, events, and alarms
• May additionally include its own automation and sequence-control functions
• Typical applications include plant overview, alarm management, and remote operation

The exact allocation of tasks is project-specific. A SCADA system can contain its own automation and control logic. Conversely, an EMS can provide extensive monitoring, visualisation, and alarm functions. The system designations alone therefore do not reliably indicate the complete functional scope of a specific solution.

How Do EMS and SCADA Work Together?

In a shared system architecture, the SCADA system frequently provides the central operation and monitoring layer. The EMS performs the technical and, where applicable, energy market optimisation of the energy flows and calculates the resulting operational setpoints.

The SCADA system can provide the EMS with measurements, operating states, and availability information. Conversely, the EMS can transmit calculated power setpoints, operating modes, or enable signals to the SCADA system or directly to local controllers. The selected connection depends, among other factors, on the plant architecture, available interfaces, and requirements concerning response times and fail-safe operation.

During system planning, it must be clearly defined which system generates setpoints, how competing instructions are prioritised, and which local control system implements the commands while considering protection functions and device limitations. The specific control hierarchy remains project-specific.

Typical Application Concepts

• C&I energy systems: The EMS optimises PV, BESS, and loads, while the SCADA system provides a central overview of the energy system and production processes.
• Large-scale PV and BESS projects: The SCADA system handles higher-level operational monitoring, while the EMS implements charging and discharging schedules or other energy strategies.
• Hybrid and off-grid systems: The EMS coordinates generators, storage systems, and other generation assets. The SCADA system supports operation, condition monitoring, and fault analysis.

Benefits, Limitations, and Technical Requirements

Combining both systems can establish a clear division of responsibilities between plant monitoring, operation, and energy optimisation. At the same time, potential overlaps may arise in data acquisition, alarm management, visualisation, and control. Data ownership, setpoint priorities, operating modes, and responsibilities should therefore be clearly defined during the system planning stage.

Technical implementation requires suitable measuring devices, controllable components, and compatible communication interfaces. Defined operating limits, a consistent time base, and rules for communication failures are equally important. Fast protection and safety functions generally remain within local device or plant control systems and should not depend solely on a higher-level platform.

Implementation with EcoPhi

EcoPhi combines local EMS and plant control functions with typical monitoring, visualisation, alarm, and analysis functions. The solution can collect measurements and operating states, visualise energy flows, and analyse historical data. As a local EMS, EcoPhi can implement operating strategies such as peak shaving, self-consumption optimisation, feed-in limitation, or the execution of external schedules.

In plants with an existing SCADA system, EcoPhi can be integrated as the local EMS and plant control layer. Measurements, status information, and setpoints can be exchanged through suitable project-specific interfaces. Whether an additional separate SCADA system is required depends on the plant size, operating concept, available interfaces, and project-specific SCADA requirements. Additional integration or engineering services may be necessary.

Conclusion

EMS and SCADA systems have different functional priorities, but their functions can overlap and the two systems can complement each other within a plant architecture. The decisive factor is the clear definition of tasks, interfaces, setpoint priorities, and responsibilities.

Frequently Asked Questions

Is an EMS the Same as a SCADA System?

No. An EMS and a SCADA system have different primary functions, even though modern systems may include functions from both areas.

Can an EMS Be Operated Without a SCADA System?

Yes. If the EMS provides the required monitoring, visualisation, and operation functions, a separate SCADA system is not necessary in every project. The decision depends on the size of the plant and the operator’s requirements.

Which System Provides the Setpoints for PV and BESS?

This is project-specific. The EMS often calculates the operational setpoints, while local controllers, PLCs, or device control systems implement them while considering technical limits and protection functions.

Can EcoPhi Be Integrated with an Existing SCADA System?

If suitable interfaces are available, EcoPhi can exchange measurements, status information, and setpoints with an existing SCADA system. The specific integration depends on the system architecture and the communication protocols used.