DDSU666-D
The Chint DDSU666-D is the official single-phase smart meter for photovoltaic systems with Solax X1 series hybrid inverters. It measures import, export, and total energy bidirectionally with class 1 accuracy. Features RS485 Modbus RTU communication, 35 mm DIN rail mounting, and IP54 protection. Essential for enabling export control and the zero grid feed-in function.
The Chint DDSU666-D is the single-phase smart energy meter designed to operate in synergy with Solax X1 series hybrid inverters (X1-Mini, X1-Air, X1-Boost, X1-Hybrid G4). Thanks to RS485 Modbus RTU communication, it transmits real-time energy flow data to the inverter, enabling advanced self-consumption management functions.
Why is a smart meter needed in a photovoltaic system?
Without a smart meter, the inverter only knows how much it produces, but not how much you are consuming from the grid. The DDSU666-D measures the connection point to the grid and communicates to the inverter the difference between production and consumption, allowing export control to be activated and zero feed-in to be set, as required by many local distributors (e.g., ENEL Distribuzione) and by CEI 0-21 regulations.
DDSU666-D Technical Specifications
| Model | DDSU666-D (Chint / Solax) |
| Network type | Single-phase 1P+N |
| Nominal voltage | 230/400 Vac |
| Nominal current | 80 A (direct connection) |
| Frequency | 50–60 Hz |
| Accuracy | Class 1 |
| Communication protocol | RS485, Modbus RTU (ID:1) |
| Protection rating | IP54 |
| Mounting | DIN rail 35 mm |
| DIN modules occupied | 2 modules (36 mm) |
| Dimensions | 98 × 36 × 65 mm |
| Self-consumption | ≤ 1 W |
| Display | LCD |
| Installation | Indoor (electrical panel) |
| Compatibility | Solax X1-Mini, X1-Air, X1-Boost, X1-Hybrid G4 |
When is the DDSU666-D meter mandatory?
The DDSU666-D is required whenever the Solax single-phase inverter needs to manage the power fed into the grid. In Italy, the CEI 0-21 standard requires compliance with the feed-in limits agreed with the distributor: without a smart meter, the inverter cannot dynamically adjust its output to the user's instantaneous consumption. It is also mandatory for the activation of Ritiro Dedicato and for the configuration of net metering with limitation.
What is included in the supply?
- DDSU666-D smart meter
- RS485 communication cable for connection to Solax inverter
- Installation guide
Frequently Asked Questions
Does the DDSU666-D work with all Solax single-phase inverters?
Yes. The DDSU666-D is compatible with the entire range of Solax single-phase inverters: X1-Mini, X1-Air, X1-Boost, and X1-Hybrid G4. For three-phase systems, the DTSU666-D or DTSU666-CT model is required. The "-D" version indicates direct connection (up to 80 A), with no need for external current transformers.
Can I use the DDSU666-D to set zero feed-in to the grid?
Yes. The DDSU666-D is the device that enables the Export Control function of Solax inverters. Once correctly installed at the grid connection point and RS485 communication is configured, you can set the maximum exportable energy value from the inverter menu (including 0 W for true zero feed-in).
Does the DDSU666-D also measure household consumption or only feed-in?
The DDSU666-D is a bidirectional meter: it measures both the energy imported from the grid (consumption) and the energy exported (feed-in), as well as instantaneous power, voltage, current, and power factor. Placed at the grid connection point, it provides the inverter with all the data needed to calculate actual consumption and optimize self-consumption.
How is the DDSU666-D installed in the electrical panel?
The DDSU666-D is mounted on a standard 35 mm DIN rail and occupies 2 modules (36 mm). It should be positioned on the incoming line from the grid, before the distribution panel. It is connected in series on the phase and neutral, then connected to the inverter via RS485 communication cable (shielded 2-wire cable, cross-section 0.25–1 mm²) on the dedicated meter ports. Installation must be carried out by qualified electrical personnel.
Does the DDSU666-D require an external power supply or is it powered from the line?
The DDSU666-D is powered directly from the single-phase AC line (230 Vac) to which it is connected, with no need for a separate auxiliary power supply. Its self-consumption is less than 1 W. This makes it extremely easy to integrate into the existing electrical panel without additional modifications.
