Sungrow Smart Meter Wiring and Zero Export Setup Guide

This guide provides definitive instructions for wiring Sungrow DTSU666 and DTSU666-20 smart meters and configuring zero export functionality with Sungrow hybrid inverters. Accurate installation ensures your solar system complies with grid regulations by preventing unwanted power export and provides precise real-time monitoring via iSolarCloud.

1. Safety First: Essential Precautions

Before commencing any wiring or installation work, prioritize safety to prevent electrical hazards and equipment damage.

• Isolate Power: De-energize the main distribution board and isolate all circuit breakers.
• Discharge Capacitors: Switch off all AC and DC isolators and wait at least 5 minutes before opening inverter wiring compartments. This allows internal capacitors to safely discharge.
• Authorized Personnel: Opening the inverter enclosure is authorized-service work.

2. Sungrow Smart Meter Overview

Sungrow smart meters, specifically the DTSU666 (Single-Phase / 3-Phase) and DTSU666-20 (Three-Phase) models, are crucial for monitoring energy flow and enabling zero export. These meters communicate with Sungrow hybrid inverters via RS485.

3. RS485 Communication Wiring

The smart meter communicates with the inverter using a dedicated RS485 interface.

3.1. Cable Requirements

Use shielded twisted-pair CAT5e or CAT6 cable for RS485 connections. This type of cable prevents electromagnetic signal distortion, ensuring reliable communication.

3.2. Terminal Connections

Connect the communication lines to the RS485-A and RS485-B terminals on the smart energy meter. Sungrow hybrid inverters communicate with smart energy meters via dedicated RS485 communication terminal blocks.

4. Current Transformer (CT) Clamp Installation

Correct CT clamp installation is vital for accurate power measurement and zero export functionality.

4.1. Location

The smart meter and CTs must measure total power flow at the main grid connection point before any sub-distribution boards. This ensures all household loads and grid interactions are accurately monitored.

4.2. Orientation

Position external current transformers on incoming grid phases with arrows pointing towards the household loads. This orientation tells the inverter the direction of current flow, distinguishing between grid import and export.

4.3. Three-Phase Installations

For three-phase installations, ensure voltage phase inputs (UA, UB, UC) match the corresponding CT phase sensor wiring strictly. Incorrect phasing can lead to inaccurate readings.

5. Zero Export Configuration via iSolarCloud

Once the smart meter and CTs are wired, configure the zero export setting using the iSolarCloud app.

5.1. Access iSolarCloud

Log in to your iSolarCloud account.

5.2. Enable Feed-in Limitation

In the iSolarCloud app, enable 'Feed-in Limitation'.

5.3. Set Export Limit

Set the export power limit to 0 kW for zero grid export. This setting instructs the inverter to modulate its output to prevent any power from being sent back to the grid.

6. Verification and Troubleshooting

After setup, verify that your system is operating correctly and troubleshoot common issues.

6.1. Real-Time Power Flow

Accurate meter wiring enables iSolarCloud to display live generation, household consumption, and grid import/export flows. Monitor these values to confirm correct operation.

6.2. Reverse CT Troubleshooting

If grid consumption shows as generation in iSolarCloud, reverse the CT clamp orientation on the incoming line. This indicates that the CTs were initially installed with the arrows pointing in the wrong direction.

By following these steps, you ensure your Sungrow solar system operates efficiently and in compliance with zero export requirements, providing reliable energy management and monitoring.