M1-40
The Solax M1-40 is a single-phase smart meter rated at 40 A with 1 CT 100A/40mA included, designed to enable export control, zero feed-in, and self-consumption optimization on Solax single-phase inverters (X1-MINI, X1-BOOST, X1-SMART, X1-Hybrid, X1-FIT). 50 ms refresh, RS485 Modbus RTU, plug-and-play CT, automatic CT direction correction, remote configuration via SolaxCloud APP.
The Solax M1-40 is a single-phase smart meter rated at 40 A, designed for precise measurement of energy flows in residential single-phase photovoltaic systems. It is the component that enables Solax inverters to activate advanced functions such as export limitation (zero feed-in), self-consumption optimization, and intelligent battery management in storage systems. The package includes 1 CT of 100 A / 40 mA with a plug-and-play terminal.
Why does the Solax inverter need a meter?
An inverter without a meter only knows how much it produces, but does not know what happens at the grid connection point. Without this information, it cannot:
- limit the power fed into the grid to comply with zero feed-in requirements set by the grid operator
- decide when to charge or discharge the storage battery to maximize self-consumption
- provide accurate consumption data to the SolaxCloud monitoring system
The M1-40 measures in real time the power exchanged on the single-phase grid connection line and transmits it to the inverter via RS485 Modbus RTU, allowing the system to evolve from "a PV that produces" to "an intelligent energy system".
M1-40 Technical Specifications
| Product code | SOL-M1-40 |
| Type | Single-phase smart meter, single measurement channel |
| Network type | Single-phase (1P) |
| Voltage range | 220 - 240 V AC |
| CT included | 1 CT of 100 A / 40 mA |
| Compatible CTs (expansion) | 100 / 200 / 400 / 600 / 1000 / 1500 / 2000 A / 40 mA |
| Refresh rate | 50 ms (high sampling speed) |
| Communication | RS485 Modbus RTU |
| Wireless transmission | Compatible with Wi-BR (up to 200 m horizontal / 20 m vertical) |
| CT connection | Plug-and-play |
| Auto-correction | Automatic CT direction detection |
| Remote configuration | SolaxCloud APP |
| Safety | Electrical isolation between strong and weak current circuits |
| Display | Integrated LCD |
| Dimensions | 100 × 18 × 65 mm |
| Weight | ~500 g |
| Warranty | 24 months |
Compatible Solax Inverters
The M1-40 is designed to be connected exclusively to single-phase inverters in the Solax range:
- Single-phase string inverters: X1-MINI G4, X1-BOOST G4
- Single-phase hybrid and storage inverters: X1-SMART G2, X1-Hybrid G4 (single-phase version)
- Single-phase retrofit inverters: X1-FIT G4
Important: according to the official Solax manual, the M1-40 can be connected only to single-phase inverters. For three-phase systems, you need to use the M3-40 model (3 CTs included) or M3-40 Dual (for systems with two generation devices).
Main Functions
- Precise single-phase measurement of voltage, current, active/reactive power, power factor, frequency, and energy
- 50 ms refresh rate: very fast response time, essential for effective export control and for managing load transients in storage systems
- Plug-and-play CT: the pre-wired CT terminal drastically reduces wiring time and connection errors
- Intelligent CT direction adaptation: the meter automatically detects CT direction errors and self-corrects — fewer site returns for the installer
- Remote configuration via SolaxCloud APP: change parameters remotely without being physically on site
M1-40, M3-40 or M3-40 Dual: how to choose?
- Single-phase system with one Solax X1 inverter → M1-40 (this product)
- Three-phase system with one Solax inverter → M3-40
- Three-phase system with two generation devices to monitor (e.g. Solax storage retrofit on existing PV of another brand, dual inverter) → M3-40 Dual
Frequently Asked Questions
Is the M1-40 mandatory to activate export control on the Solax inverter?
Yes. To activate export control (zero feed-in or grid feed-in limitation) on single-phase Solax systems, a compatible meter is required. The M1-40 is the standard choice for residential single-phase systems with an X1 inverter. Without a meter, the inverter produces but cannot comply with a feed-in limit required by the grid operator.
Can I use the M1-40 on a three-phase system?
No. According to the official Solax manual, the M1-40 can only be connected to single-phase inverters. For three-phase systems, you need to use the M3-40 (3 CTs included) or the M3-40 Dual (for configurations with two generation devices, such as Solax storage retrofit on an existing PV of another brand).
Is the CT included in the package?
Yes. The package includes 1 CT of 100 A / 40 mA, already pre-wired with a plug-and-play terminal. For systems with higher currents, CTs of 200, 400, 600, 1000, 1500, and 2000 A / 40 mA are available as accessories, to be paired with the meter while maintaining the same transformation ratio.
Can I configure the meter remotely?
Yes, via the SolaxCloud APP. In addition, the meter has automatic self-correction functions for CT direction: once wired, it analyzes the data and reconfigures itself if it detects a reversal, drastically reducing the need for corrective interventions after installation.
What cable is needed for communication with the inverter?
Shielded twisted pair RS485 cable (recommended 0.5-1 mm² with shielding) or RJ45 Cat 5e cable depending on the communication port of the Solax single-phase inverter. The meter's Quick Installation Guide provides a pin-out table for each X1 inverter series. Alternatively, the meter is compatible with the Solax Wi-BR module, which allows wireless connection up to 200 m horizontally.
How is the meter physically installed?
The M1-40 is mounted on a DIN rail or on the wall inside the electrical panel. The CT is clipped onto the phase of the grid connection line (the arrow printed on the CT must point towards the load/inverter, with the grid side on the other). The RS485 cable connects the meter to the Solax X1 inverter. Once powered, the meter starts automatic direction detection and configures itself.
