Paralleling Sunsynk Ecco with Acure Inverter Guide

Key Takeaways

• Original Ecco and newer Acure hybrid inverters can be paralleled successfully when following strict manufacturer integration rules.
• The Acure must always serve as the Master unit in the communications hierarchy because it represents the newer hardware generation.
• Both machines must share the exact same power capacity rating; differing capacity ratings cannot be paralleled on the same AC bus.
• Main Control Unit (MCU) firmware must be identical across both units, whereas LCD screen firmware remains model-specific due to display hardware differences.
• In South Africa, paralleling inverters on a shared residential or commercial supply alters embedded generation capacity and requires an updated Certificate of Compliance (CoC) and municipal SSEG notification.

System Expansion: Mixing Ecco and Acure Inverters

Many South African homeowners and commercial property operators who installed Sunsynk hybrid inverters during early stages of load shedding eventually require capacity expansion. When adding a secondary inverter to power larger inductive loads or increase battery throughput, installers frequently discover that the original Ecco model has been superseded in distributor channels by the newer Acure generation.

This raises a crucial technical question: can an older Ecco hybrid inverter operate in parallel with a newly purchased Acure unit?

The official manufacturer answer is affirmative, but reliable operation requires strict adherence to three non-negotiable engineering requirements. Paralleling microgrid inverters requires perfect phase synchronization, shared load-sharing algorithms, and uninterrupted high-speed data exchange across parallel communication ports. Failing to configure the units correctly creates circulating AC currents, communication bus lockups, and immediate trip faults.

Master-Slave Hierarchy Rule

The fundamental rule governing mixed Ecco and Acure installations dictates which unit commands the parallel system:

The Acure Inverter MUST be configured as the Master due to it being the newer Inverter. This follows the same rationale that when 2 or more Ecco Inverters are connected in parallel that the newest unit is configured as the Master.

In any multi-inverter parallel cluster, the Master inverter performs several central supervisory duties:

1. Grid Monitoring: The Master reads external CT coils or smart energy meters at the main point of common coupling.
2. Current Allocation: It calculates the instantaneous aggregate household load and commands Slave units on how much power to produce.
3. Battery Management: It interfaces with the primary lithium battery management system over CAN bus, coordinating charging and discharging current limits across the entire bank.

Because the Acure represents a revised hardware revision with updated internal processing components, assigning the Acure as the Master ensures that the most capable processing hardware oversees system-wide timing and communication routines.

Parallel Menu Configuration

On the Acure master unit:

• Navigate to the parallel settings menu.
• Enable parallel mode.
• Set the unit as Master (Modbus address one).

On the legacy Ecco unit:

• Navigate to the parallel settings menu.
• Enable parallel mode.
• Set the unit as Slave (Modbus address two).

Capacity and Sizing Matching Rule

The second mandatory requirement addresses physical power ratings:

The Acure MUST be the same size Inverter as the original Ecco. Again this follows the same rational that when 2 or more Ecco Inverters are connected in parallel, they must be the same size Inverter.

Inverter paralleling depends on symmetrical impedance and proportional power division across shared AC busbars. If an installer attempts to parallel an eight-kilowatt Acure with an older five-kilowatt Ecco:

• The internal transformer and switching bridge impedances will not match.
• During rapid load steps—such as an air conditioning compressor or borehole pump starting—the smaller unit can be pushed into severe overcurrent while the larger unit carries minimal load.
• Voltage waveform distortion and circulating currents between inverter AC output terminals will cause nuisance trips and potential semiconductor damage.

Always ensure that both machines share the identical kilowatt capacity rating before attempting physical interconnection.

MCU and Comms Firmware Synchronization

Firmware alignment is the most technical requirement when pairing Ecco and Acure hardware.

The Acure and Ecco Models share the same MCU firmware for each size of Inverter, therefore the Acure and the Ecco Inverters MUST have identical MCU Firmware installed. This again follows the same rationale that when 2 or more Ecco Inverters are connected in parallel, they must have identical Firmware.

The Main Control Unit (MCU) firmware dictates the core inverter power electronics:

• PWM switching frequency.
• Phase-locked loop (PLL) tracking of the utility grid.
• Anti-islanding detection speeds.
• Dynamic droop control for load sharing in islanded backup mode.

If MCU firmware builds differ between the Master and Slave, subtle timing discrepancies in frequency-watt response or voltage regulation will cause the inverters to fight each other for voltage control, resulting in instantaneous inverter trip codes.

Understanding LCD Display Firmware Differences

While MCU firmware must match perfectly, display firmware behaves differently:

NOTE: The LCD / Comms Firmware versions are different due to the Ecco having the White screen and the Acure having the Black screen.

The physical human-machine interface differs significantly between product generations:

• The original Ecco features the classic white graphic display with physical pushbuttons.
• The Acure features an upgraded dark graphical display with updated capacitive navigation and menu hierarchies.

Installers must never attempt to flash the Acure LCD display firmware onto an Ecco inverter, or vice versa. The communication card and LCD driver chips are hardware-specific. When requesting parallel-compatible firmware from technical support, specify that you are linking an Ecco to an Acure so that identical MCU code is matched with the appropriate display software builds for each machine.

Physical Cabling and Installation Checklist

Before commissioning the mixed parallel system, verify the complete hardware installation:

1. AC Commoning Sub-Board: Both inverters must connect to a common AC distribution sub-board with dedicated isolation circuit breakers for Grid input, Load output, and Auxiliary ports.
2. Parallel Communication Leads: Connect high-quality RJ45 communication leads between the parallel ports on the inverters. Use the parallel In and Out ports in a daisy-chain arrangement, and verify that the bus termination switches or resistors are set correctly on the end units.
3. Shared Battery DC Bus: Both inverters must connect to a common DC battery busbar rather than separate unlinked batteries. Cable lengths from each inverter to the common DC busbar must be identical in length and cross-sectional area to ensure balanced battery current draw.

Safety Warning: Always isolate all AC distribution breakers and open battery DC disconnects before plugging in or removing parallel communication cables. Inserting parallel leads on live hardware can damage internal communication transceivers.

South African Electrical Regulations and Grid Standards

Under South African electrical regulations, adding a secondary inverter to expand generating capacity constitutes a significant structural modification to the electrical installation:

• Wiring Code Compliance: The shared AC distribution sub-board, interlocked changeover switchgear, and neutral-earth bonding systems must be certified by a registered installation electrician. A supplementary Electrical Certificate of Compliance (CoC) must be issued.
• Grid Interconnection Standards: Paralleling two single-phase inverters increases total export capacity. Municipal electricity distributors (such as City of Cape Town, eThekwini, or City Power) and Eskom impose strict capacity limits on residential single-phase supplies. If total inverter capacity exceeds municipal single-phase thresholds, the supply may require upgrading to a three-phase connection or configuring zero-export limitations.
• Anti-Islanding Safety: When the grid fails during load shedding, both inverters must disconnect synchronously within prescribed statutory trip times to prevent hazardous backfeeding into the municipal distribution network.