Short Definition
Off-grid monitoring refers to the monitoring of an energy system without a permanently available connection to the public grid. It records energy flows, system states, and operating reserves within an island grid that typically combines photovoltaic (PV) systems, battery energy storage systems (BESS), diesel generators, and local loads. Its purpose is to provide transparency regarding security of supply, energy availability, and technical faults.
Off-Grid Monitoring at a Glance
- In an off-grid system, local generation, storage, and consumption must be continuously balanced.
- Monitored parameters include PV generation, consumption, BESS state of charge and power, generator operation, fuel reserves, frequency, and voltage.
- At remote sites, local data buffering and plant control that operates independently of the internet connection are particularly important.
- Monitoring provides visibility into operating states and available reserves. Active interventions are performed by the local control system and the control functions of the participating devices.
How Does an Off-Grid System Maintain Stable Operation?
In a grid-connected energy system, short-term power imbalances can normally be compensated for through grid import or export. This is not possible in a fully independent off-grid system. Generation, storage, and consumption must therefore be continuously balanced within the island grid.
For stable island-grid operation, at least one grid-forming component must establish the voltage and frequency reference. This function can be performed, for example, by a generator or a grid-forming battery inverter. The monitoring system records the operating state of this component and deviations in the relevant electrical parameters. However, the rapid electrical stabilisation of the island grid is performed by the internal control system of the grid-forming source, not by the monitoring system.
What Does Off-Grid Monitoring Measure and Analyse?
Monitoring systems consolidate measurements from the different components. For the PV system, relevant data includes current power, energy yield, inverter status, and fault messages. For the BESS, important parameters include charging and discharging power, state of charge, available energy, battery voltages, temperatures, warnings, and fault states. For diesel generators, monitored values can include power, operating status, runtime, fuel level, and, where the necessary measurements are available, fuel consumption.
The electrical conditions within the island grid are also monitored. Relevant parameters include frequency, phase-specific voltages and currents, active and reactive power, power factor, phase imbalance, switching states, and fault conditions. Depending on the application, harmonics and other power-quality indicators may also be recorded. Deviations can indicate an insufficient power balance, overload conditions, or operation close to the limits of a grid-forming component.
Time-synchronised measurements can be used to calculate energy balances, the share of local energy demand supplied by PV, battery utilisation, generator runtimes, and fuel consumption. Historical data can help identify recurring load peaks, insufficient PV yields, or declining usable battery capacity.
A currently critical supply situation can be detected based on the state of charge, available battery capacity, load, generation, and generator availability. Forecasting future supply shortages additionally requires suitable load and generation forecasts as well as corresponding analytical logic. Depending on the system, weather forecasts and planned operating states can also be considered.
Local or cloud-based alarms can be triggered when thresholds are violated or when device faults or communication failures occur.
Where Is Off-Grid Monitoring Used?
Typical applications include:
- Remote commercial and industrial sites: Monitoring the energy supply at locations where an economically viable grid connection is unavailable.
- Telecommunications sites: Monitoring mobile communications and radio sites with high availability requirements and difficult or costly on-site access.
- Agricultural facilities: Monitoring the supply of pumps, cooling systems, processing equipment, and other loads using PV, BESS, and generators.
- Permanently operated island grids: Monitoring fully grid-independent local energy systems.
- Sites with unstable or intermittently available grid supply: Comparable monitoring functions are relevant at these sites, even though they are not purely off-grid systems. Grid-connected operation, island operation, and transitions between the two operating modes must be recorded separately.
Benefits, Limitations, and Technical Requirements
Off-grid monitoring provides a centralised view of energy flows, system components, and remaining energy reserves. Critical states of charge, unexpectedly high consumption, unusually long generator runtimes, and technical faults can be detected at an early stage. This makes it easier to plan maintenance activities and evaluate operating strategies based on actual data.
Monitoring alone cannot provide a power reserve, start a generator, or shed loads. These functions require a local control system. The control system can, for example, account for state-of-charge limits and power reserves, transmit setpoints to controllable components, coordinate generator start-up, or shed predefined loads.
Rapid voltage and frequency stabilisation remains the responsibility of the grid-forming devices and their internal control systems. A higher-level plant control system coordinates component operation over longer control intervals. Monitoring provides the measurements and status information required for this purpose but does not automatically perform these control functions.
Technical requirements include suitable measuring devices, reliable device interfaces, and time-consistent data acquisition. Measurement errors, failed sensors, and communication interruptions must be detected and clearly identified. Otherwise, incorrect values can lead to an inaccurate assessment of available energy and operating reserves.
Because internet connectivity is often unstable at remote sites, measurements should be stored locally with unambiguous timestamps. Once the connection has been restored, the data should be transmitted in the correct chronological order. Operationally relevant protection, control, and regulation functions must operate independently of a permanently available cloud connection.
How Can Off-Grid Monitoring Be Implemented with EcoPhi?
EcoPhi can integrate PV systems, BESS, generators, energy meters, and other components of an off-grid system through the available interfaces. Operating data can be collected and buffered locally, visualised, and transmitted for remote monitoring, analysis, and alarm notifications.
With an appropriate project configuration, a local control system can additionally coordinate PV generation, the BESS, controllable loads, and generator operation. The specific functionality depends on the system architecture, available device interfaces, component control capabilities, and requirements for autonomous operation. Proprietary devices or customised operating strategies may require additional integration and engineering services.
Conclusion: Transparency for Autonomous Energy Systems
Off-grid monitoring provides transparency regarding energy flows, plant states, and operating reserves within an island grid. This enables critical conditions and technical faults to be detected at an early stage. Stabilising and actively coordinating the system, however, requires grid-forming components and a suitable local control and regulation architecture.
Frequently Asked Questions About Off-Grid Monitoring
What Is the Difference Between Off-Grid Monitoring and Off-Grid Control?
Monitoring records, stores, and visualises measurements and operating states. A control system actively intervenes in system operation, for example by specifying BESS setpoints, starting a generator, or shedding loads. Rapid voltage and frequency stabilisation is performed by the internal control system of a grid-forming component.
Which Parameters Are Particularly Important for Off-Grid Monitoring?
The most important parameters include generation and consumption, BESS state of charge and available energy, generator output, fuel reserves, frequency, phase-specific voltages and currents, and device, switching, and communication states.
Does Off-Grid Monitoring Work Without an Internet Connection?
Measurements can be collected and buffered locally if the monitoring system is designed accordingly. Remote access and cloud-based alarm notifications are unavailable or available only to a limited extent during a connection outage.
Can Monitoring Detect an Impending Energy Supply Shortage?
A currently critical supply situation can be identified from present measurements and system states. Forecasting a future supply shortage additionally requires load and generation forecasts as well as corresponding calculation logic. This forecasting capability is not automatically included in every monitoring system.