Sunsynk Inverter Exporting When It Should Not In South Africa

Key Takeaways

• Unintended export to the grid is a compliance issue in South Africa, requiring specific inverter settings to prevent it.
• Check your Sunsynk inverter's 'Work Mode' and 'Solar Export' settings first to ensure they are configured for zero export.
• Correct installation and communication of the CT clamp or external meter are critical for accurate grid power monitoring and export control.
• Incorrect CT clamp placement, wiring, or interference can lead to doubled or absent grid-side load readings, impacting export control.
• Grid protection settings are for registered persons only; changing them can invalidate your Certificate of Compliance (CoC) and connection agreement.

Why Your Sunsynk Inverter May Be Exporting Power Unintentionally

In South Africa, exporting power to the grid without prior approval from Eskom or your municipality is a compliance exposure. Municipalities like Cape Town require non-feed-in systems to block reverse power flow. If your Sunsynk inverter is sending power back to the grid when it should not, it is typically due to incorrect inverter settings or issues with the devices that monitor grid power flow, such as the CT clamp or an external meter.

How Your Sunsynk Inverter Controls Grid Export

Your Sunsynk inverter manages its interaction with the grid through a combination of internal settings and external monitoring devices. The inverter uses a Current Transformer (CT) clamp or an external energy meter to measure the power flow at your main incomer. This allows it to determine how much power your property is consuming from or sending to the grid. Based on these readings and your configured work mode, the inverter adjusts its output to meet your load, charge batteries, or, if allowed, export excess power.

Essential Settings to Prevent Grid Export

To ensure your Sunsynk inverter does not export power to the grid, you must configure specific settings. These settings are found within the inverter's menu system.

Checking CT Clamp and External Meter Configuration

Accurate grid monitoring is fundamental to preventing unwanted export. Issues with your CT clamp or external meter can lead to incorrect readings, causing the inverter to misinterpret grid conditions and export power.

Common CT Clamp Issues and Solutions:

• Incorrect Placement: The CT clamp must be placed on the live incomer cable of your property, before any henley blocks or distribution boards.
• Incorrect Direction: The arrow on the CT clamp must point towards the inverter for single-phase systems, or towards the loads (what Sunsynk's UK documentation calls the consumer unit — the distribution board) for three-phase Eastron SDM630MCT installations.
• Wiring Errors: For single-phase inverters, the white tail of the CT clamp should be in pin 3 and the black tail in pin 4. For three-phase, ensure correct pin assignments for each phase.
• Interference: Keep CT cables at least 12 inches (approximately 30cm) away from other CTs (e.g., for EV chargers) and avoid running them closely paralleled to AC cables or in the same trunking. Coiled CT cables can also cause interference.
• Cable Length: The CT cable length should ideally be no more than 10 metres, extendable up to 15 metres. For longer runs, an external Eastron meter is required.
• Incorrect Ratio: Ensure the 'CT ratio' setting in the inverter's 'Advanced Settings' matches your installed CT clamp or external meter. The Sunsynk CT coil ratio is 2000:1, while the Eastron SDM120CT coil ratio is 3000:1. High Voltage series inverters may use a 6000:1 ratio.

For detailed guidance on CT clamp installation and troubleshooting, refer to our guide on Sunsynk CT coil wrong readings.

External Meter Configuration (Eastron Meters): If you are using an external Eastron meter, ensure it is correctly wired and configured.

• Enabling the Meter: In the inverter's 'Advanced Settings', 'Ex_Meter_for_CT' must be enabled, and the correct 'Meter Select' type chosen.
• Wiring: Follow the specific wiring diagrams for your Eastron model (e.g., SDM120CT, SDM230, SDM630MCT). Incorrect wiring (e.g., solid colour cores paralleled with colour/white cores in CAT-6 cable) can lead to doubled grid-side load readings.
• Communication: A 'W04_Meter_Comm_Fail' warning indicates a communication issue. Check RS485 wiring and ensure the meter's communication settings (Address, Baud Rate, Parity) match the inverter's requirements.

Grid Relay Disconnection and Reconnection

The grid relay is a safety mechanism. If your inverter detects grid voltage or frequency outside its acceptable thresholds, it will disconnect from the grid to protect itself and the local network. This is a normal safety function.

• Disconnection: The inverter will instantly disconnect for 60 seconds when grid parameters are outside its set limits.
• Reconnection: After 60 seconds, the inverter will attempt to reconnect to the grid if the voltage and frequency have returned to normal operating ranges.
• Monitoring: You can view the 'Relay Status' in the Sunsynk Connect app under the 'Equipment' tab, then select the 'Grid' tab. Note that 'Lifelynk' inverters do not track grid relay status in the app.

What you can change yourself, and what you cannot

You can safely adjust settings related to your inverter's work mode, export limits, and battery charging parameters. These include 'Solar Export', 'Work Mode', 'Export Power Limiter', 'Max Solar Power', 'Grid Peak-Shaving', and 'Live Price mode'. You can also verify and correct CT clamp placement and wiring, and ensure the correct 'CT ratio' and 'Meter Select' settings are applied.

However, any settings under 'Grid Settings' that define voltage and frequency thresholds for grid connection and disconnection are critical grid protection parameters. These settings are typically configured by a registered person during installation to comply with South African grid codes like NRS 097-2-1. You must not change these grid protection settings yourself. Altering them can breach your connection agreement with Eskom or your municipality and invalidate your Certificate of Compliance (CoC), posing a safety risk and potential legal consequences. Always consult a qualified and registered electrician for any adjustments to grid protection settings. For more information on compliance, refer to our guide on SSEG registration in South Africa.

What the published sources do not tell you

While Sunsynk provides extensive documentation, some specifics relevant to the South African context are not explicitly detailed. The documentation often references UK grid standards (G98/G99) and terms like "DNO" (Distribution Network Operator). For South African installations, the relevant standard is NRS 097-2-1, and the grid operator is Eskom Distribution or your local municipality. The specific voltage and frequency thresholds for grid connection in South Africa are not provided in the general Sunsynk support articles, as these are typically set by the installer according to local regulations. Additionally, the documentation does not provide a list of "compatible tariffs" for the 'Live Price mode' in South Africa, meaning this feature may not be fully functional or applicable without specific local tariff integration.