Overview
The Hoymiles Smart Meter (HMeter-CT-T120-RW) is a three-phase smart meter designed for accurate energy monitoring and energy management in compatible Hoymiles systems. It supports 3P3W and 3P4W grid configurations, measures currents up to 120 A, and supports both WLAN and RS-485 communication. When connected to a compatible Hoymiles energy storage system, it helps optimize self-consumption, manage battery charging and discharging, and support zero-export control.
Important: Electrical installation and commissioning should be performed by a qualified electrician in accordance with applicable local electrical regulations. The meter is designed for DIN-35 rail installation and uses plug-and-play CT connections.
What's in the Box
- 1 × HMeter-CT-T120-RW
- 1 × Antenna
- 1 × Terminal block
- 3 × Current Transformers (CTs)
Before Installation
1. Check the Package
The package includes:
- 1 × HMeter-CT-T120-RW
- 1 × Antenna
- 1 × Terminal block
- 3 × Current Transformers (CTs)
2. Check the Installation Conditions
The HMeter-CT-T120-RW supports:
| Specification | Value |
|---|---|
| Grid type | 3P3W / 3P4W |
| Voltage | 90–277 V AC L-N |
| Line-to-line voltage | 156–480 V AC L-L |
| Current | 0–120 A |
| Measurement accuracy | ±1% |
| Communication | WLAN / RS-485 |
| Mounting | DIN-35 rail |
| Operating temperature | -40°C to +70°C |
| Protection rating | IP20 |
Safety Precautions
Before installation:
- Read the product manual carefully.
- Switch off the relevant power supply before making electrical connections.
- Verify that the circuit is de-energized before working on it.
- Do not install the meter in a location exposed to water or excessive moisture.
- Do not modify or disassemble the meter.
- Make sure all wiring and terminals are securely connected.
- Electrical installation and commissioning must be performed by qualified personnel.
The HMeter-CT-T120-RW has an IP20 enclosure and is intended for installation inside an appropriate electrical distribution cabinet.
Installation
1. Mount the Smart Meter
The HMeter-CT-T120-RW uses a compact 1P-width DIN-35 rail mounting design.
Step 1
Install the meter onto a standard 35 mm DIN rail inside the distribution cabinet.
Step 2
Make sure the meter is securely clipped onto the DIN rail and cannot move.
Step 3
Install the supplied antenna in the designated antenna connection.
The compact 1P-width design allows the meter to be installed in a limited amount of space.
2. Connect the Current Transformers
The HMeter-CT-T120-RW uses three plug-and-play current transformers (CTs) for three-phase current measurement.
Connect the CTs according to the corresponding phases:
- CT1 → L1
- CT2 → L2
- CT3 → L3
Make sure each CT corresponds to the correct voltage phase measured by the meter.
Important: The CT installation direction is important for correct power measurement.
Before commissioning:
- Verify the CT is installed on the correct conductor.
- Verify the CT phase corresponds to the correct voltage phase.
- Check the CT orientation according to the markings on the CT and the official wiring diagram.
- Make sure the CT connector is fully inserted into the meter.
Do not rely on a generic CT wiring diagram for the final installation. Use the terminal designation and wiring diagram in the latest Hoymiles HMeter-CT-T120-RW user manual.
The manufacturer specifically identifies the CT connection as a plug-and-play connection for simplified wiring.
3. Connect the Voltage Measurement
The meter supports both:
- 3P4W systems
- 3P3W systems
The voltage connections must correspond to the phases measured by the CTs.
For a typical three-phase four-wire installation:
L1 → Meter voltage input L1
L2 → Meter voltage input L2
L3 → Meter voltage input L3
N → Meter neutral input
The exact terminal assignment should always be checked against the terminal markings in the current HMeter-CT-T120-RW user manual before energizing the meter.
4. Check the CT and Phase Assignment
Before switching on the system, verify:
| Check | Requirement |
|---|---|
| CT1 | Corresponds to L1 |
| CT2 | Corresponds to L2 |
| CT3 | Corresponds to L3 |
| Voltage L1 | Corresponds to CT1 |
| Voltage L2 | Corresponds to CT2 |
| Voltage L3 | Corresponds to CT3 |
| CT direction | Correct according to CT marking |
| CT connectors | Fully inserted |
Incorrect phase assignment or CT orientation can result in incorrect power-flow measurements.
6. Commissioning
After completing the installation:
Step 1: Energize the Meter
Restore power according to the applicable electrical installation procedure.
Step 2: Check Communication
Confirm that the meter is connected to the Hoymiles system through WLAN or RS-485.
Step 3: Check Voltage Readings
Verify that the measured voltage values are reasonable and correspond to the actual grid configuration.
Step 4: Check Current Readings
Verify that the current measurements from CT1, CT2 and CT3 are displayed correctly.
Step 5: Check Power Direction
Confirm that imported and exported energy are displayed correctly.
If power flow is shown in the wrong direction, immediately check:
- CT orientation
- CT-to-phase assignment
- Voltage-to-phase assignment
- System configuration
7. Smart Meter Configuration
Once communication is established, configure the meter in the compatible Hoymiles system.
Depending on the supported system and firmware, available functions may include:
- Real-time energy monitoring
- Grid import/export monitoring
- Zero-export control
- Energy management
- Charging/discharging optimization
Availability of specific functions may depend on the connected Hoymiles product, firmware version and system configuration.
8. Troubleshooting
(1) The Meter Is Powered On but Cannot Connect
Check:
- WLAN connection
- Antenna installation
- Network availability
- RS-485 wiring, if applicable
- Compatibility with the connected Hoymiles product
- Firmware version
(2) Energy Readings Are Incorrect
Check:
- CT orientation
- CT-to-phase assignment
- Voltage-phase assignment
- Grid type configuration
- CT connections
(3) Power Direction Is Reversed
Check the orientation of the relevant CT.
(4) One Phase Shows Abnormal Data
Check whether:
- The corresponding CT is correctly connected.
- The CT is installed on the correct conductor.
- The corresponding voltage phase is correctly connected.
- The CT and voltage phase assignments match.
9. Important Installation Notes
The HMeter-CT-T120-RW is a three-phase smart meter supporting 3P3W and 3P4W systems. Its current measurement range is 0–120 A.
The meter is intended for use with compatible Hoymiles products. Hoymiles currently states that the device is compatible with selected products in the HiBattery, HiFlow and HiFlow Pro series and is not generally intended as a universal smart meter for products from other manufacturers.
For the most accurate installation, the latest HMeter-CT-T120-RW User Manual and Datasheet should be used for terminal assignments and wiring details. The Hoymiles Shop currently lists User Manual HMeter-CT-T120-RW Global EN Rev1.2 and Datasheet Rev1.3, both updated June 29, 2026.
10. Connect to the Hoymiles System
The HMeter-CT-T120-RW supports WLAN and RS-485 communication.
For compatible Hoymiles systems, the smart meter can provide real-time energy data and support energy-management functions such as monitoring and export-control applications. The Hoymiles Shop currently lists the meter as compatible with selected HiBattery, HiFlow and HiFlow Pro products.
WLAN Connection
- Power on the smart meter.
- Open the compatible Hoymiles application/system interface.
- Follow the device-pairing instructions.
- Connect the meter to the appropriate WLAN network.
- Confirm that the meter is online.
- Verify that real-time energy data is being received.
RS-485 Connection
If the compatible Hoymiles system uses RS-485 communication:
- Switch off the relevant power supply.
- Connect the RS-485 communication cable according to the terminal designations.
- Check the communication polarity and wiring.
- Power the system back on.
- Verify communication in the compatible Hoymiles system.
Do not connect RS-485 terminals based solely on wire color. Always follow the terminal labels and the latest Hoymiles wiring diagram.
