Using an Eastron Meter as a Customer Limitation Scheme (CLS) Failsafe for G100

The purpose of this Engineering Recommendation (EREC) is to state the requirements for Customer Export or Import Limitation Schemes (CLS) that are used to limit the export to and/or the import from the Distribution Network of a licensed Distribution Network Operator (DNO).

A typical CLS may be used in the following scenarios:

• Installing generation with an aggregate Current Rating greater than the permitted export to the network and limiting the peak export
• Connecting significant new loads which cannot operate at their full capacities at the same time without exceeding the import capacity from the network
• Using the flexibility of the Customer’s loads and generation to stay within import or export limits

Compliant Models and ENA Reference Codes

N.B. the inverters must be used with an Eastron meter which is listed as fully compatible with Sunsynk equipment. Please see article 'Eastron Meters: CT Selection and Settings' for more information.

How the requirements are met:

✅ 1. Real-time export measurement

Export must be measured in real time using a device capable of reliable and accurate readings.

✔ Met by:

• Eastron SDM630 Modbus meter (MID-certified, real-time power metering)

• Connected via RS-485 Modbus to the inverter

• Measures import/export, voltage, current, and power factor at the grid point using CTs

✅ 2. Active control of export power

System must dynamically control generation to ensure export does not exceed the agreed limit.

✔ Met by:

• Sunsynk inverter reads real-time export via the meter

• It adjusts its output power every 1 second (or faster) to ensure export stays within the programmed limit (e.g., 0 kW)

• This is handled internally via firmware (no external controller required)

✅ 3. Failsafe behavior

In the event of failure (meter, comms, CT, or power), the export must not exceed the set limit.

✔ Met by:

• Sunsynk inverters are programmed to enter failsafe mode if:

  • Meter stops sending data

  • RS-485 link fails

  • CTs become disconnected or damaged

• In failsafe mode, the inverter:

  • Reduces export to 0 kW or a pre-set low value

  • May enter island mode (if backup load exists)

  • Or shuts down grid export entirely

This behavior satisfies G100’s clause:

“Any failure in the export limiting scheme must result in continued compliance or default to a safe export condition (e.g. 0 kW).”

✅ 4. Tamper resistance and secure settings

User settings (export limits, Modbus mapping) must be secure and protected.

✔ Met by:

• Export control settings in Sunsynk are password-protected under the installer menu

• Modbus and CT parameters are locked once configured

• This ensures only authorised personnel can modify the limit or disable failsafe protection

✅ 5. Single point of control and measurement

Export must be measured at the correct point (typically just before the grid connection)

✔ Met by:

• Eastron meter CTs are installed on the main grid feed cable

• Export power is measured before the consumer unit / load DB

• Ensures total system export is monitored — not just inverter output

Summary: How the Eastron + Sunsynk System Complies with G100