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Solinteg M2HT 25–50 kW — Paralleling & Generator Guide Rev 1.0.2

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Paralleling and Diesel Generator Solutions

Solinteg M2HT 25⁠–⁠50 kW Hybrid Inverters

Paralleling and Diesel Generator Solutions
M2HT-25K · 29.9K · 30K · 40K · 50K Application GuideRev 1.0.2, 9 Nov 2026
aerl.com.au Australian edition

Contents

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
01

IntroductionOverview, system types, solutions in this guide

Document

Revision1.0.2 (Australian edition)
Effective11 / 2026
AudienceDesigners and licensed installers
Inverters in parallelUp to 10 (500 kW)
Generator sizeAt least 1.5 × total inverter power
Extra hardwareEDA back-up box, ATS
AppSolinteg IntegHub
FormatA4 · 29 pages

1.1Overview

Paralleling. Up to ten Solinteg M2HT 25–50 kW hybrid inverters can run in parallel, on both the on-grid side and the back-up side, for a total of up to 500 kW. Parallel systems suit high-power sites such as factories, shopping centres and business parks, and keep the site supplied when the grid is unavailable or unstable. The inverters offer six work modes, including time-of-use (ToU), to reduce energy costs.

Diesel generator solutions. Where the grid is unreliable, a diesel generator (DG) adds a second power source, so the site stays supplied during planned and unplanned outages. Solinteg offers generator solutions for single inverters, and for parallel systems using the Solinteg EDA back-up box and an automatic transfer switch (ATS). These cover applications from residential to commercial, with intelligent management of the whole system.

When the grid fails, the generator can supply the loads and also charge the battery, which makes the system more stable.

The generator and the inverters never supply the loads at the same time

Size the generator and the inverter system so that each one on its own can supply the full load.

Australian requirements

Design and install the system in accordance with AS/NZS 3000, AS/NZS 4777.1, AS/NZS 5139 and, for generators, AS/NZS 3010. Grid-connected systems need network approval, and multiple-inverter systems may need central protection. Check with the local network service provider before you design the system. All installation work must be done by licensed electrical workers.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

1.2System Types

TypeOutputDefinitionApplication
Single25–50 kWOne inverterWith battery backup. Suits grid-connected and off-grid sites, and sites that need on/off-grid switching because of frequent outages.
On/off-grid parallel50–500 kWUp to 10 inverters in parallel on both the on-grid side and the back-up sideSystem-level battery backup. Suits sites with frequent outages. Reduces reliance on the grid, and keeps the loads running when the grid is down.
Off-grid parallel50–500 kWUp to 10 inverters in parallel on the back-up sideSystem-level battery backup. Suits off-grid sites only. Forms a microgrid supplied by PV and batteries.
On-grid parallel50–500 kWUp to 10 inverters in parallel on the on-grid sideNo system-level battery backup. Suits sites with a stable grid. Reduces electricity costs through peak/off-peak arbitrage or response to grid dispatch.

1.3Solutions in This Guide

TypeSolutionSection
Single inverterGenerator on the inverter GEN port, with grid3.1
Single inverterGenerator through an ATS, with grid3.2
Single inverterGenerator on the inverter on-grid port, no grid3.3
Off-grid parallelScenario 1: grid only3.4
Off-grid parallelScenario 2: generator only3.5
Off-grid parallelScenario 3: grid and generator3.6
Off-grid parallelScenario 4: no grid, no generator3.7
On-grid parallelGrid and generator3.8
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

1.4Equipment Required

Every solution uses Solinteg M2HT 25–50 kW inverters, a three-phase diesel generator that can be started and stopped by a dry-contact (DO) signal, and a Solinteg RMM smart meter (supplied with the inverter). The generator and ATS are sourced locally.

SolutionGenerator connects atGridEDA back-up boxATSFirmware
Single inverterGEN portOn-grid or off-grid——Confirm with AERL
Single inverterOn-grid portOff-grid——Confirm with AERL
Single inverterATSOn-grid—YesConfirm with AERL
Off-grid parallel (back-up side)On-grid portOff-gridYes—Confirm with AERL
Off-grid parallel (back-up side)ATSOn-gridYesYesConfirm with AERL
On-grid parallelATSOn-grid—YesConfirm with AERL
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
02

How the System WorksOff-grid paralleling, generator output modes

2.1Off-Grid Paralleling

Master and slave control

  • Up to 10 inverters can run in off-grid parallel.
  • One master inverter controls scheduling and settings, and synchronises them to the slave inverters.
  • The master shares the power on each phase evenly across the slaves, based on the load on each of the three phases.

Work modes

Rated power

Faults

EventSystem response
A slave fails or trips on protectionThe master isolates it and the system keeps running
The master failsThe whole system shuts down
A slave's battery failsThe system keeps running and treats that slave as having no battery
The master's battery failsThe system runs only while the master has PV power

2.2Generator Output Modes

Output modeWhat the generator does
Loads onlyThe generator supplies the loads only, when required.
Loads and batteryThe generator supplies the loads first, and charges the battery with any spare capacity. Charge power = generator maximum output − load power.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

2.3Generator Control Methods

Control methodHow it works
ManualStart and stop the generator from the app. Recommended for first commissioning.
AutomaticThe generator starts automatically when the grid fails, and stops when the grid returns. Not available when the generator is connected to the inverter on-grid port.
SOCWhen the grid fails, the system supplies the loads from the battery first, and starts the generator when the battery state of charge (SOC) falls below the start setting. The generator stops when the grid returns or the SOC reaches the stop setting.
Generator control logic for manual, automatic and SOC control.
Figure 2.1 Generator control logic for manual, automatic and SOC control.
Automatic generator start

Contact AERL for current support. Manual control is not affected.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
03

WiringSingle inverter, generator on the GEN port, with grid

All the wiring diagrams in this chapter use the same legend: DC, AC phase conductor, AC neutral, CAN, RS485, digital output (DO) and digital input (DI). Point the CT arrows towards the grid.

3.1Single Inverter, Generator on the GEN Port, with Grid

Single inverter with the generator on the GEN port. The inset shows the generator start signal from COM2 (DO-COM, DO-NO).
Figure 3.1 Single inverter with the generator on the GEN port. The inset shows the generator start signal from COM2 (DO-COM, DO-NO).
BreakerFunction
S1Grid-side breaker
S2Generator breaker
S3On-grid load breaker
S4Inverter on-grid output breaker
S5Back-up load breaker
Before you design with this solution

The generator rating must be at least 1.5 × Ptotal.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

3.2Single Inverter, Generator Through an ATS, with Grid

Single inverter with the generator and grid switched by an ATS.
Figure 3.2 Single inverter with the generator and grid switched by an ATS.
Before you design with this solution

This solution needs an ATS for reliable operation. The generator rating must be at least 1.5 × Ptotal.

3.3Single Inverter, Generator on the On-Grid Port, No Grid

Single inverter off-grid, with the generator connected at the inverter on-grid port.
Figure 3.3 Single inverter off-grid, with the generator connected at the inverter on-grid port.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Before you design with this solution

The generator rating must be at least 1.5 × Ptotal.

3.4Off-Grid Parallel, Scenario 1: Grid Only

Off-grid parallel with grid only. The EDA back-up box switches the back-up loads.
Figure 3.4 Off-grid parallel with grid only. The EDA back-up box switches the back-up loads.
Before you design with this solution

This solution needs the EDA back-up box for reliable operation. All the inverters in parallel must be the same model and power rating. Otherwise the weakest inverter limits the whole system.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

3.5Off-Grid Parallel, Scenario 2: Generator Only

Off-grid parallel with a generator only, connected in place of the grid.
Figure 3.5 Off-grid parallel with a generator only, connected in place of the grid.
Before you design with this solution

This solution needs the EDA back-up box for reliable operation. All the inverters in parallel must be the same model and power rating. Otherwise the weakest inverter limits the whole system. The generator rating must be at least 1.5 × Ptotal.

3.6Off-Grid Parallel, Scenario 3: Grid and Generator

Off-grid parallel with grid and generator, switched by an ATS.
Figure 3.6 Off-grid parallel with grid and generator, switched by an ATS.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Before you design with this solution

This solution needs the EDA back-up box and an ATS for reliable operation. All the inverters in parallel must be the same model and power rating. Otherwise the weakest inverter limits the whole system. The generator rating must be at least 1.5 × Ptotal.

3.7Off-Grid Parallel, Scenario 4: No Grid, No Generator

Off-grid parallel with no grid and no generator. The loads are on the back-up side.
Figure 3.7 Off-grid parallel with no grid and no generator. The loads are on the back-up side.
Before you design with this solution

All the inverters in parallel must be the same model and power rating. Otherwise the weakest inverter limits the whole system.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

3.8On-Grid Parallel, Grid and Generator

On-grid parallel with grid and generator, switched by an ATS.
Figure 3.8 On-grid parallel with grid and generator, switched by an ATS.
Before you design with this solution

All the inverters in parallel must be the same model and power rating. Otherwise the weakest inverter limits the whole system. The generator rating must be at least 1.5 × Ptotal.

3.9EDA Back-Up Box and ATS

The EDA is a Solinteg back-up box controller. It switches seamlessly between on-grid and off-grid operation in parallel systems, keeping the system stable and making the hybrid system more reliable and resilient.

EDA back-up box circuit (left) and ATS circuit (right). The ATS main contact switches the grid (main source) and the auxiliary contact switches the generator (auxiliary source).
Figure 3.9 EDA back-up box circuit (left) and ATS circuit (right). The ATS main contact switches the grid (main source) and the auxiliary contact switches the generator (auxiliary source).
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
DeviceConnects to the inverter (master) at
Generator start signal (DO)COM2 pins 11 and 12
ATS position signalCOM2 pins 17 and 18
EDA back-up boxCOM2 pins 9 and 10

Communication wiring

The inverter reads the ATS signal on COM2 pins 17 and 18 to tell whether the grid or the generator is supplying power:

Connect EDA pins 11 and 12 to inverter COM2 pins 9 and 10. The order of the two wires does not matter.

Communication wiring between the inverter COM2 connector, the ATS and the EDA back-up box.
Figure 3.10 Communication wiring between the inverter COM2 connector, the ATS and the EDA back-up box.

3.10Rules for Off-Grid Paralleling

ItemRequirement
Number of invertersUp to 10 in off-grid parallel
Inverter modelAll inverters must be the same model and power rating
PV and batteryThe PV strings and battery capacity on each inverter must be equal, or close to equal
Communication moduleEvery inverter needs its own communication module (dongle)
Smart meterThe RMM smart meter must communicate with the master inverter
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
ItemRequirement
EDAOff-grid parallel needs the EDA back-up box
GeneratorThe generator must support start and stop by a DO (dry-contact) signal
ATSThe ATS must have a normally open (NO) auxiliary contact output for the back-up source (generator)
BreakersEvery inverter needs its own AC breaker
Phase sequenceThe phase sequence must match across all the inverters, on both the on-grid side and the back-up side
Parallel cablesThe parallel communication cables and RJ45 plugs are supplied by Solinteg
CAN busThe CAN communication of every inverter must be working. Turn on the SYNC termination resistor and the parallel CAN termination resistor on the first and last inverters only
Master positionOnly the first or the last inverter in the chain can be the master
Parallel CAN chain on the COM3 Solink ports, and the SYNC and parallel CAN termination switches.
Figure 3.11 Parallel CAN chain on the COM3 Solink ports, and the SYNC and parallel CAN termination switches.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
04

App ConfigurationOff-grid paralleling, diesel generator

All configuration is done in the Solinteg IntegHub app. Scan a code to install it, or search for IntegHub in Google Play or the App Store.

Get the IntegHub app
QR code: Android Google Play
Android
Google Play
QR code: iPhone App Store
iPhone
App Store

4.1Off-Grid Paralleling

Before you set any parameters:

  1. Complete the installation and wiring.
  2. Create a plant in Solinteg Cloud or the IntegHub app.
  3. Add all the inverters to the plant in the app.

Then work through these five steps:

StepWhat to do
1. Check firmwareParalleling has no firmware requirement. For automatic generator start, contact AERL.
2. Set inverter rolesSet one inverter as the master and enter the number of inverters in parallel. Set the others as slaves.
3. Set the work modeSet the work mode on the master. It is synchronised to the slaves automatically.
4. Set the phase sequenceSet the grid phase sequence on the master so the inverters and the grid match. The default is auto-adaptive.
5. Custom switches (optional)Set only if the site needs it.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

Step 1: Check the firmware

  1. On the plant page, tap Device.
  2. On the Device page, tap each inverter.
  3. Check the Slave Firmware Version of every inverter in parallel.
  4. Paralleling has no firmware requirement. For automatic generator start, contact AERL.
  5. If the firmware needs updating, contact AERL support.
Checking the firmware version in the IntegHub app.
Figure 4.1 Checking the firmware version in the IntegHub app.

Step 2: Set the inverter roles

  1. On the Device page, tap the settings button of each inverter.
  2. On the Parameter settings page, tap Feature parameters.
  3. On the master inverter, set the role to Master and enter the number of inverters in parallel.*
  4. On each slave inverter, set the role to Slave and enter its inverter address.**
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Setting the master and slave roles.
Figure 4.2 Setting the master and slave roles.

* The master starts working only when the number of inverters it detects online matches the number entered.

** Slave addresses must start at 1, and be unique and consecutive.

Step 3: Set the work mode

  1. On the Device page, tap the settings button of the master inverter.
  2. On the Parameter settings page, tap Basic params.
  3. Tap Work mode.
  4. Select the work mode and tap Confirm.

In an off-grid parallel system, set the work mode on the master inverter only.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Setting the work mode on the master inverter.
Figure 4.3 Setting the work mode on the master inverter.

Step 4: Set the phase sequence

  1. On the Device page, tap the settings button of the master inverter.
  2. On the Parameter settings page, tap Feature parameters.
  3. Tap Grid phase sequence settings.
  4. Leave the setting at Auto adaption (the default and recommended setting), or select Positive sequence or Negative sequence to suit the site.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Setting the grid phase sequence.
Figure 4.4 Setting the grid phase sequence.

Step 5: Custom switches (optional)

  1. On the Device page, tap the settings button of the master inverter.
  2. On the Parameter settings page, tap Custom switches.
  3. Set the switches to suit the site.
Warning

We do not recommend changing the custom switches. If a change is needed, contact AERL support first.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Custom switches.
Figure 4.5 Custom switches.

4.2Diesel Generator

Step 1: Add the generator in the IntegHub app

  1. You need a hybrid inverter plant in Solinteg Cloud before you can use this function.
  2. On the Devices page, tap +, choose Third-party devices and tap the Diesel generator icon.
  3. Name the generator. Tap Superior device and select the serial number of the inverter that the generator connects to.
  4. Tap Unconnected to choose the access method.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Adding the generator as a third-party device.
Figure 4.6 Adding the generator as a third-party device.

Step 2: Select the access method

  1. Select how the generator is connected (GEN port, ATS or grid port) and tap Confirm.
  2. Tap the arrow next to Control mode and select the control method (section 2.3).
Note

A generator connected at the inverter on-grid (grid) port offers Manual control and SOC control only. A generator connected at the GEN port or through an ATS also offers Automatic control.

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Access methods and control modes. The upper control-mode list applies to the GEN port and ATS; the lower one to the grid port.
Figure 4.7 Access methods and control modes. The upper control-mode list applies to the GEN port and ATS; the lower one to the grid port.

Step 3: Set the generator parameters

  1. Tap the arrow next to Output mode and select:
    • Load only: once started, the generator supplies the loads only
    • Load & Charge battery: once started, the generator supplies the loads and charges the battery.
  2. Set the other generator parameters (such as rated power, maximum power limit, start and stop SOC, start-up delay and stop delay) from the generator rating plate and the site requirements.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Generator parameters.
Figure 4.8 Generator parameters.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
05

Questions and Answers

How do I connect the EDA back-up box to the inverter?

Connect EDA pins 11 and 12 to inverter COM2 pins 9 and 10. The order of the two wires does not matter.

How big should the generator be?

At least 1.5 × Ptotal, the total rated power of the inverters. A smaller generator is more likely to give an unstable supply.

Can the system avoid exporting power to the generator?

Yes. Because the generator and the inverters never supply the loads at the same time, no power is exported to the generator, provided the system is wired and configured as this guide describes.

What happens if an inverter in a parallel system fails?

The parallel system works as a whole. A failed slave inverter is isolated and the rest keep running. If the master fails, the system stops.

How do I keep the system running if the master fails and the replacement hasn't arrived?

Make another inverter the master:

  1. Choose the slave next to the original master as the new master.
  2. Disconnect the CAN cable between the new master and the original master.
  3. Move the meter communication cable to the new master.
  4. Turn on the termination resistors on the new first and last inverters.
  5. Reconfigure the system in the IntegHub app.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

How do I choose an ATS?

The following is a guide only. Have the final design done by a qualified professional.

  1. The ATS current rating should be at least the system's maximum operating current, plus a 10–25% margin.
  2. Allow for the generator's starting current and short-circuit capacity.
  3. For loads that cannot tolerate an interruption, consider a closed-transition ATS.
  4. In three-phase systems, use a 3-pole or 4-pole ATS. Use 4-pole if the neutral must be switched (check the MEN arrangement required by AS/NZS 3000 and AS/NZS 3010).
  5. Rate the ATS for the ambient temperature, derating and enclosure rating (IP) of the installation.

How does M2HT paralleling differ from the earlier MHT 25–50 kW?

MHT 25–50 kWM2HT 25–50 kW
Inverters in parallelUp to 4 off-grid; up to 10 on-gridUp to 10 off-grid; up to 10 on-grid
FirmwareARM 05 or later and DSP 05 or laterNo firmware requirement for paralleling
Work modes76 (no economic mode)
Parallel connectionCOM2 pins 17 and 18, twisted pairCOM3 Solink ports (RJ45)
Termination (DIP switches)Turn on PAR CAN 120R on the first and last invertersTurn on SYNC 120R and PAR CAN 120R on the first and last inverters
MHT: parallel connection on COM2 pins 17 and 18.
Figure 5.1 MHT: parallel connection on COM2 pins 17 and 18.
MHT: PAR CAN 120R switch.
Figure 5.2 MHT: PAR CAN 120R switch.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
M2HT: Solink 1 and Solink 2 ports on COM3.
Figure 5.3 M2HT: Solink 1 and Solink 2 ports on COM3.
M2HT: SYNC 120R and PAR CAN 120R switches.
Figure 5.4 M2HT: SYNC 120R and PAR CAN 120R switches.
Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
06

Technical Support

Contact AERL for help with system design, installation, commissioning, firmware, warranty and spare parts for Solinteg inverters, EDA back-up boxes and batteries in Australia.

AERL technical support

  • Phone: 1800 950 865
  • Email: [email protected]
  • Web: aerl.com.au
  • Address: AERL, 1/75 Bluestone Circuit, Seventeen Mile Rocks QLD 4073, Australia

When you contact AERL, have the following ready:

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

Notes

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

Notes

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2

Notes

Solinteg M2HT 25–50 kW · Paralleling & Generator GuideRev 1.0.2
Manufactured by Solinteg
Supplied and supported in Australia by AERL

Australian Energy Research Laboratories

Address

1/75 Bluestone Circuit
Seventeen Mile Rocks QLD 4073
Australia

Contact

[email protected]
[email protected]

aerl.com.au Phone1800 950 865