How to connect Growatt string inverters with Reduxi controller
Integrate the Growatt MAX 100-150KTL3-X string inverter with the Reduxi Controller via Modbus RTU. This gives you maximum flexibility and lower energy costs.
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Product photo of the Growatt MAX 100-150KTL3-X string inverter on a white background: a large white wall-mounted inverter housing with a dark grey front panel at the top carrying the GROWATT logo and a round display with a green ring on the right. Black mounting brackets and DC connectors are at the bottom.
1 Preparation
1.1 Technical documentation
The Growatt website lists all Growatt inverters and installation guides. The user manual of the Growatt MAX 100-150KTL3-X is an example of an installation guide.
- Growatt products – Full list of Growatt inverters and installation guides
- Growatt MAX 100-150KTL3-X LV/MV user manual (EN, 2025-07) – Installation guide for the Growatt MAX 100-150KTL3-X
- Growatt MAX 100-150KTL3-X LV product page – Product page with current manuals and quick guide
1.2 Required equipment
- Reduxi Controller
- Growatt MAX 100-150KTL3-X string inverter
- Twisted-pair shielded cable for the RS-485 communication line (recommended)
- Laptop or tablet with internet access to configure the device in Reduxi
2 Connect the inverter to the Reduxi Controller via RS-485 Modbus RTU
Modbus RTU is used to access the interface of the string inverter. You must therefore make a physical connection.
2.1 Find the RS-485 connector on the inverter
The Modbus communication connectors are on the bottom of the inverter. The RS-485 connector is at location H in the picture (bottom view of the terminals).
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Diagram from a manual, Fig 3.1, line drawings of an inverter. Top: label Front view: with a drawing of the front of the inverter housing; letter A points to the housing body and letter B points to the round display at the upper right; caption Fig 3.1. Bottom: label Bottom view(Termial): with a drawing of the underside showing groups of DC terminals, round cable glands and a connector block at the right end. Letters under the glands and connectors: C, D, E, F, H, I, J. A red circle marks a round black port in the upper area above the gland labelled H, and a second red circle marks the letter H below it.
2.2 Connection of a single inverter
- Use twisted-pair shielded wire for the RS-485 communication line (recommended).
- For single-machine communication, connect the communication line to pin 3/4 and its shielding layer to pin 1.
- The figure shows the RS-485 terminal types: terminal type 1 and terminal type 2.
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Diagram and table from a manual (Fig 6.6) showing the RS-485 terminals of an inverter. Top: two round multi-pin connector faces, labelled Terminal type 1 and Terminal type 2 (image cropped at the top). On Terminal type 1 the pin numbers 3 (left, red circle) and 1 (right, red circle) are marked, with further pin numbers 4, 7, 8, 12, 13, 16. Terminal type 2 shows numbering 1 to 5, 6 to 11 and 12 to 16. Table with columns Port, PIN, Description (left half) and Port, PIN, Description (right half). Left half: Shield ground, PIN 1/2, 485-1 / 485-2 PE shield; RS485-1 IN, PIN 3, 485-1 A1; RS485-1 IN, PIN 4, 485-1 B1; RS485-1 OUT, PIN 5, 485-1 A1; RS485-1 OUT, PIN 6, 485-1 B1; RS485-2, PIN 7, 485-2 A1; RS485-2, PIN 8, 485-2 B1. The rows Shield ground, PIN 3 and PIN 4 (RS485-1 IN) are enclosed in a red box. Right half: DRMS port with PIN 9 DRM1/5, PIN 10 DRM2/6, PIN 11 DRM3/7, PIN 12 DRM4/8, PIN 13 REF/GEN, PIN 14 DRM0/COM; PIN 15/16 485-1 Matching resistance (port RS485-1 Matching resistance).
Connect the inverter to the Port 1 or Port 2 interface of the Reduxi Controller. In the picture, 485-1 A1 connects to A+ (Port 1) and 485-1 B1 connects to B- (Port 1).
| Growatt inverter | Reduxi Controller |
|---|---|
| 485-1 A1 | A+ (Port 1) |
| 485-1 B1 | B- (Port 1) |
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Diagram from a manual: Figure 3: Communication interfaces pinout (marked as number 3). Drawing of the front edge of a controller housing: a round power socket labelled PWR on the left, an RJ45 Ethernet socket labelled ETH, four small status LED symbols, and a 6-pin green terminal block marked with a black circle with the number 3. Above the terminal block: GND, PORT 1 (A B), PORT 2 (A B), 5V. Pins are numbered 1 to 6. Legend below: 1. Common ground; 2. A + (port 1); 3. B - (port 1); 4. A + (port 2); 5. B - (port 2); 6. Auxiliary +5V DC output.
2.3 Connection of multiple inverters in parallel
- Use twisted-pair shielded wire for the RS-485 communication line (recommended).
- Link RS485 OUT (pin 5 = A, pin 6 = B) of the first inverter to RS485 IN (pin 3 = A, pin 4 = B) of the next inverter.
- Repeat the daisy-chain connection for all additional inverters (A to A, B to B).
- Enable the termination resistor (pins 15/16) on the last inverter in the chain.
3 Log in to the Reduxi web interface
You can open the Reduxi web interface in two ways:
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Screenshot of three Reduxi mobile app screens side by side, with cyan boxes and number badges 2 to 4. Left screen (dashboard, dark theme): menu icon at top left marked with a box and badge 2; 'reduxi' logo; tabs 'Real time data' (active) and 'Statistics'; price 5.79 € and temperature 3.2 °C; energy flow diagram with a house in the centre (-1.25 kW) and icons with values 69.0 W, 1.3 kW, 1.1 kW (red ring), -165.0 W with 97 % (red ring) and 0.0 W values at the bottom; tabs 'Power' and 'Energy'; bottom navigation: Dashboard, Diagnostics, Device control, Settings. Middle screen (side menu): 'reduxi' logo, 'Number of locations: 1233', heading 'Reduxi device management', entries '+ Add Reduxi location' and 'Reduxi devices' (marked with a box and badge 3), then 'My profile' and 'About app'. Right screen (device page): Back; picture of a black Reduxi controller with two Ethernet ports; status 'Connected'; card 'Update available': 'New update is available for your Reduxi device.' with button 'Download and install update'; card 'Connect to configurator': 'Tunnel connection enables remote access to your Reduxi configurator, without need to be connected to the same local network.' with button 'Activate tunnel connection' (marked with a box and badge 4); card 'Unit details' with field 'Unit ID'.
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Screenshot made of two parts side by side. Left part: Reduxi mobile app screen on a dark background. Top: Back button; picture of a black Reduxi controller with two Ethernet ports and a terminal block; status 'Connected' with a Wi-Fi icon. Card 'Update available': 'New update is available for your Reduxi device.' with button 'Download and install update'. Card 'Connect to configurator' with a key icon: 'Tunnel connection enables remote access to your Reduxi configurator, without need to be connected to the same local network.' and button 'Open configurator', marked with a cyan box and number badge 5. Below: card 'Unit details' with a field 'Unit ID' (value not visible). Right part: Reduxi Configurator opened in a browser, marked with a cyan frame and number badge 6. Header: back arrow, 'Tunnel connection', reload icon. Left sidebar with icons (lightning, chip, lightning bolt, bar chart, gear). Page 'Home' with a green link icon. Green notice: 'New patch available. Click here to apply.' with a close X. Time 09:12:56. Energy flow diagram with a house in the centre (1.700 kW) and icons for grid (0.000 kW), solar (1.700 kW), battery (green, 0.000 kW and 0.800 kW), a device at left (0.900 kW), electric vehicle and a charger or device at bottom. Label 'Energy manager' at the bottom.
http://reduxi.local. You can find the controller's IP address in your router's device list or in the Reduxi app under Reduxi devices.admin · Password: admin (factory default)Text description of this image
Screenshot of the Reduxi Configurator login page in a Chrome browser window. The address bar shows 'Not secure' and 'reduxi.local'; the address bar is marked with a cyan box and an enlarged copy of it (cyan box, text 'Not secure reduxi.local') is shown at the left, connected by a cyan line. Page background: light grey line drawing of a house with solar panels (green), a wall box, an inverter, a car and a charger. Top left: 'reduxi configurator' logo. Login box in the centre with title 'Login', a language selector (English flag, 'English'), a username field and a password field, and a dark 'Login' button.
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Screenshot of the Reduxi Configurator web interface after login, light theme. Top left: 'reduxi configurator' logo. Header bar: 'Home' at left, green 'Connected' status at top right. Left sidebar: expanded section 'Devices' with a list of entries, then collapsed sections 'Manager' and 'Configuration' and 'Settings'. Main area: energy flow diagram. House in the centre with ring, value 24.20 kW. Grid icon at top left, 24.20 kW (red dot on its line). Solar icon at top right, value '-'. Left icon (battery or device), 6.700 kW (green dot on its line). Right icons (battery storage and a device), values '-'. EV charger icon at bottom left, 31.00 kW. A further device icon at bottom right. Label 'Energy manager' below the house.
4 Add the inverter to Reduxi
Use these steps to add a new inverter or to edit an existing one.
4.1 Basic settings
Log in locally to the Reduxi Configurator on the controller (see Point 3) and click + Add device.
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Screenshot of the top of the Reduxi Configurator left menu. Logo: reduxi Configurator. Devices (expanded, minus sign) contains only the button + Add device (framed). Below: Strategies (+), Utility Rate Plan, Settings (+).
In the first step (basic settings), select the basic parameters of the device:
- Device type:
Hybrid inverter - Type:
Growatt - Name: a name of your choice
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Screenshot of the Reduxi Configurator device wizard, step 1 Basic settings. Step indicator: 1 Basic settings (active), 2 Communication channel (greyed). Heading: Basic settings. Fields: Device type *: Hybrid inverter; Type *: Growatt; Name *: Growatt MAX 100-150KTL3-X. Buttons: Back, Next.
4.2 Communication settings
The second step sets up the communication channel between the Reduxi Controller and the Growatt string inverter. These settings are for RS-485 Modbus RTU. Define these fields:
| Parameter | Value |
|---|---|
| Modbus Unit ID | Modbus unit ID of the inverter |
| Inverter Type | Select the inverter type |
| Battery Type | Select the battery type |
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Screenshot of the Reduxi Configurator form Communication channel and device configuration (cropped, step indicator not included). Fields: Connection *: Local serial port; Port *: Port 1; Baud rate *: 9600 bits/s; Data bits *: 8; Stop bits *: 1; Parity *: None; Modbus unit ID *: 1; Inverter type *: MAX TL3-X (hint: Select the type of inverter.); Battery type *: SPH (field highlighted as active; hint: Select the type of battery.). Buttons: Back, Test communication, Done.
4.3 Test communication
Click Test communication at the bottom of the wizard. It reads the Growatt string inverter once and saves nothing. If the test succeeds, click Done: only Done creates the device.
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Screenshot of the bottom button bar of a Reduxi Configurator page. Left: button 'Back'. Right: button 'Test communication' (marked with a cyan box) and dark button 'Done'.
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Screenshot of the Reduxi Configurator page 'Communication channel and device configuration'. Connection *: TCP/IP (dropdown). IP *: 192.168.50.243, with button 'Scan for IP'. Port *: 502, with button 'Test port'. Modbus unit ID *: 1. Buttons at the bottom: Back (left), Test communication and Done (right). The Done button is marked with a cyan box.
5 Check the readings
5.1 Last measurements
After communication is established, check the values under Devices – Growatt in the Reduxi Configurator as an additional test.
5.2 Enable control by Reduxi
To integrate the inverter into the Reduxi strategy, set the control type under Devices – Growatt to AUTO. Only then do strategy commands affect the inverter.
To achieve maximum flexibility and energy cost reduction with dynamic prices and dynamic tariffs, define a strategy as described in Strategies for Reduxi controller.
✓ Summary
Preparation (Points 1–2): Use the Growatt documentation. Connect the RS-485 line from port 485-1 of the inverter to Port 1 or Port 2 of the Reduxi Controller (A1 to A+, B1 to B-).
Growatt inverter (Point 2): For several inverters, daisy-chain RS485 OUT to RS485 IN and enable the termination resistor (pins 15/16) on the last inverter.
Add to Reduxi (Points 3–4): Log in to the Reduxi web interface. Add the device, set Modbus Unit ID, Inverter Type and Battery Type, and run Test communication.
Go live (Point 5): Check the readings. Set the control type to AUTO and define a strategy.
→ Common issues
| Issue | Solution |
|---|---|
| Test communication fails | Check the RS-485 wiring: 485-1 A1 to A+ and 485-1 B1 to B- on Port 1 of the Reduxi Controller. Check the Modbus Unit ID. |
| Several inverters do not respond | Check the daisy chain (RS485 OUT to RS485 IN, A to A, B to B). Enable the termination resistor (pins 15/16) on the last inverter. |
| Open configurator does not open or stays empty | The tunnel is not active yet. Wait about 30 seconds and check that the controller is online. |
Login with admin is rejected |
The password was changed during installation. Ask the installer. The Reduxi account password does not work here. |
reduxi.local does not load |
Your device is not in the same network as the controller. Use the IP address or the tunnel connection. |
| Communication test fails, device shows offline | Check reachability, IP address / port / unit ID, and that the protocol is enabled on the device. |