DTSU666-D
The Chint DTSU666-D is the three-phase smart meter with direct connection for photovoltaic systems with Solax X3 series inverters. It measures all three phases bidirectionally up to 80 A, with RS485 Modbus RTU communication, class 1 accuracy, and IP54 protection. Essential for export control and zero grid feed-in on three-phase systems.
The Chint DTSU666-D is the direct-connected three-phase smart energy meter for photovoltaic systems with Solax X3 series inverters. With RS485 Modbus RTU communication, it measures three-phase energy flows in real time at the grid connection point, enabling dynamic export control and advanced self-consumption management.
Why is the DTSU666-D needed in a three-phase system?
In a three-phase photovoltaic system, without a smart meter the inverter produces without knowing how much you are consuming on the grid at any given moment. The DTSU666-D measures the connection point on all three phases and communicates the data to the inverter, which can then dynamically adjust its output power, activate zero feed-in to the grid, and maximize self-consumption. In Italy, the CEI 0-21 standard requires this function for systems with export limitation agreed with the utility company.
DTSU666-D Technical Specifications
| Model | DTSU666-D (Chint / Solax) |
| Network type | Three-phase 3P+N |
| Nominal voltage | 3×230/400 Vac |
| Nominal current | 80 A (direct connection) |
| Frequency | 50–60 Hz |
| Accuracy | Class 1 |
| Communication protocol | RS485, Modbus RTU |
| Protection rating | IP54 |
| Mounting | 35 mm DIN rail |
| DIN modules occupied | 7 modules (72 mm) |
| Dimensions | 98 × 72 × 65 mm |
| Self-consumption | ≤ 1 W |
| Display | LCD |
| Installation | Indoor (electrical panel) |
| Compatibility | Solax X3-Hybrid G4, X3-MIC, X3-PRO, X3-IES (three-phase) |
DTSU666-D vs DTSU666-CT: which version do you need?
The DTSU666-D is the direct connection version: the network cables physically pass through the meter terminals, without external current transformers. It is the standard choice for most residential and commercial three-phase systems with current up to 80 A. If the system exceeds 80 A or has large cross-section cables, you need the DTSU666-CT with current transformers.
What is included in the package?
- DTSU666-D smart meter
- RS485 communication cable for connection to Solax inverter
- Installation guide
Frequently Asked Questions
Is the DTSU666-D compatible with all Solax three-phase inverters?
Yes. The DTSU666-D is compatible with the entire range of Solax three-phase inverters: X3-Hybrid G4, X3-MIC, X3-PRO, and X3-IES. For single-phase systems (X1 series), you need the DDSU666-D model. When the system exceeds 80 A, choose the CT version DTSU666-CT.
Can I use the DTSU666-D for zero feed-in on a three-phase system?
Yes. The DTSU666-D is the device that enables the Export Control function of Solax three-phase inverters. Installed at the grid connection point and connected via RS485, it allows you to set the desired export limit from the inverter menu, including full zero feed-in (0 W). Any change in consumption is detected in real time and the inverter adjusts accordingly.
Does the DTSU666-D measure all three phases separately?
Yes. The DTSU666-D measures voltage, current, active and reactive power on each of the three phases separately, as well as the total for all three phases. The LCD display shows the parameters of each individual phase and the overall flow in real time. This information is transmitted to the inverter via RS485 for optimal export management.
How is the DTSU666-D installed in the electrical panel?
The DTSU666-D is mounted on a 35 mm DIN rail and occupies 7 modules (72 mm). It should be positioned on the incoming three-phase line from the grid, before the distribution panel. It is connected in series on the three phases and neutral, then via shielded RS485 cable (cross-section 0.25–1 mm²) to the communication port of the Solax inverter. Installation must be carried out by qualified electrical personnel.
Does the DTSU666-D require additional configuration in the inverter?
Yes, once physically connected, you need to access the advanced settings of the Solax inverter (menu Advance Settings → Export Control) to set the maximum export value. The meter is automatically recognized via Modbus: the inverter identifies the DTSU666-D as soon as RS485 communication is active. No additional drivers or software configurations are required.
