SOFAR ESI-8K-T18kW three-phase high-voltage hybrid inverter, 3 MPPT

Overview

The ESI-8K-T1 is the 8kW model of the ESI-5-12K-T1 series: 8kW rated output, 8.8kVA maximum apparent power and 8kW battery discharge at up to 24A. Its three MPP trackers accept up to 16kWp of recommended PV power, one string each at up to 20A. Maximum AC input current from the grid is 24.2A per phase at 380V. Efficiency reaches 98.0% maximum and 97.0% European weighted, and the unit weighs 30kg.

• Rated output from 5 to 12kW on 400V three-phase grids
• Three MPPT with AFCI, 20A per tracker, 1000V input
• Stacks with one to six BTS 5K modules: 5.12–30.72kWh
• Backup output with 10ms switchover and 100% unbalanced load
• Up to six units in parallel on-grid, three off-grid
• IP66 enclosure, fanless natural cooling, -30…+60°C

How it works

The ESI-5-12K-T1 combines a three-tracker PV inverter, a battery charger and a grid-forming backup output in one IP66 housing. Each tracker accepts one string at up to 20A and operates from 160 to 950V. The single battery port works with high-voltage lithium packs between 350 and 435V, communicates with the BMS over CAN and charges at up to 10kW; discharge power follows the model rating, with a 10kW ceiling on the 12kW version.

The inverter sits on top of SOFAR BTS 5K battery modules of 5.12kWh each, forming the PowerAll all-in-one system with one to six modules (5.12–30.72kWh). SOFAR also documents systems without battery, with modules added later, and systems without PV where the battery charges from the grid. An existing PV inverter of any brand can be integrated through a second energy meter so that its output also charges the battery.

Key features

When the grid fails, the BACKUP port keeps critical loads running after a default switchover time of 10ms. It can deliver twice the rated power for 10 seconds and supports fully unbalanced three-phase loads. With the grid present, an optional unbalanced-support function tries to keep the power exchanged with the grid equal on all three phases. Every model has arc-fault detection on the PV inputs, Type II surge protection on DC and AC, and fanless cooling.

Installation and compatibility

The inverter is wall-mounted or stacked on its battery base, indoors or outdoors, with at least 30cm free on all sides; at 30kg it should be handled by two people. Grid and backup terminals take 6–10mm² copper cable, PV and battery inputs 4–6mm². Each inverter needs its own AC breaker. Residual current detection is built in; where an external RCD is required, SOFAR suggests Type A with 100mA or higher.

A three-phase smart meter on RS485, direct-connected or with CTs, provides grid data for self-consumption control and export limitation. Up to six inverters of identical model and battery configuration run in parallel on-grid, three in off-grid mode, with the meter on the master and link cables under 10m. The grid port can alternatively be configured for a generator with manual or automatic start.

Monitoring and settings

A Wi-Fi stick logger (4G optional) sends operating, energy and alarm data to the SofarCloud portal and app. Work modes are self-use (default), feed-in priority, peak shaving, time-of-use and passive mode for external controllers over Modbus RTU. Export can be limited on the sum of the exporting phases or on the three-phase total, and a dry contact can switch an external load on a schedule or on PV surplus.

Questions and answers