Chint DDSU666 Single Phase Bidirectional Smart Energy Meter

Chint DDSU666 — Overview

The Chint DDSU666 is the standard single-phase bidirectional smart energy meter for grid-tied and hybrid solar installations in South Africa. Required by Eskom and most municipalities as part of the NRS 097 SSEG approval process, this MID-certified meter accurately records both energy imported from the grid and energy exported by your solar system. It is widely specified by solar installers across Gauteng, the Western Cape, and KwaZulu-Natal.

Technical Specifications

• Voltage: 230V AC, 50Hz single phase
• Current rating: 5(80)A continuous
• Accuracy class: IEC 62053-21 Class 1 (active energy)
• Communication: RS485 Modbus RTU
• Display: Backlit LCD with bidirectional kWh registers
• Mounting: 35mm DIN rail, 2-module width
• Certification: MID approved, CE, IEC 62053
• Operating temperature: -25°C to +55°C
• Dimensions: 36mm W x 90mm H x 65mm D

Why a Bidirectional Meter Is Required for Solar in South Africa

South African grid-tied solar legislation (NRS 097-2-1 and municipal SSEG bylaws) requires a bidirectional smart meter at the point of common coupling. This meter records both power drawn from the Eskom grid and power injected back into the grid from your solar system. Without an approved bidirectional meter in place, your municipality will not approve your SSEG application, your supply authority will not install a bidirectional import/export tariff, and your solar system cannot legally export to the grid.

Inverter Compatibility and RS485 Integration

The DDSU666’s RS485 Modbus RTU port connects directly to the RS485 input on most hybrid inverters sold in South Africa, including Sunsynk (all single-phase models), Deye (SUN-xK-SG04LP1), Growatt (SPF and SPA series), Victron Energy (via Cerbo GX USB-RS485 adapter), Sungrow (SH series), and Huawei SUN2000. This integration enables accurate zero-export limiting to prevent excess generation from being fed to the grid before your SSEG application is approved.

Installation Requirements

The DDSU666 must be installed by a registered electrician inside a dedicated metering enclosure or the main distribution board, upstream of the solar interconnection point. An RS485 shielded cable runs from the meter’s RS485 terminals to the inverter’s communications port. The completed installation requires an electrical Certificate of Compliance (CoC) and forms part of the SSEG documentation package submitted to your municipality.

Frequently Asked Questions

Is the Chint DDSU666 approved by Eskom for SSEG in South Africa?
Yes. The DDSU666 is MID certified under IEC 62053-21 and is accepted by Eskom and the majority of South African municipalities as a compliant bidirectional metering device for NRS 097 SSEG applications. Final approval depends on the specific requirements of your local supply authority.

Does the DDSU666 support zero-export limiting?
Yes. When connected to a compatible inverter via RS485 Modbus RTU, the DDSU666 provides real-time grid power data that the inverter uses to limit output and prevent power from being exported to the grid during the period before SSEG approval is granted.

What cable is required to connect the DDSU666 to my inverter?
Use a 2-core or 4-core shielded RS485 cable (0.5mm2 twisted pair). Cable length between meter and inverter should not exceed 100m. Terminate with 120-ohm resistors at each end of the RS485 bus if multiple devices are daisy-chained.

Can I install the DDSU666 myself?
No. The DDSU666 must be installed by a registered electrician in accordance with SANS 10142-1. A Certificate of Compliance (CoC) is legally required for any work on a South African distribution board.

Does the DDSU666 measure solar generation or only grid import/export?
The DDSU666 measures energy flow at its installation point. When installed at the grid connection point, it measures grid import (energy drawn from Eskom) and grid export (energy sent to the grid). Solar generation is monitored separately via your inverter’s monitoring app.