SOFAR 40KTLX-G340kW three-phase string inverter, 4 MPPT

Overview

The SOFAR 40KTLX-G3 provides 40kW of rated output and 44kVA maximum apparent power at up to 66.7A per phase. It is the first model of the series with four MPP trackers, giving eight string inputs at up to 40A per tracker, and the manual recommends up to 60000Wp of PV with 150% DC oversizing allowed. Maximum efficiency rises to 98.8%, with 98.2% European efficiency. The inverter weighs 37kg and operates from -30 to +60°C.

• Rated output 25–50kW, up to 55kVA apparent power
• Three MPPT (25–36kW) or four MPPT (40–50kW), 40A each
• DC oversizing up to 150%, suited to 500Wp+ modules
• 1100V maximum input, 180–1000V MPPT range
• Max. efficiency 98.8% on the four-tracker models
• I-V curve scan and Type II SPD on DC and AC

How it works

Each tracker takes two strings with up to 40A operating current and 50A short-circuit current, suitable for high-current modules of 500Wp and more. The 25, 30, 33 and 36kW models have three trackers, the 40, 45 and 50kW models four. The MPPT range is 180–1000V with a 200V start-up and a 620V rated input. SOFAR allows DC oversizing up to 150%, and the manual recommends up to 1.5 times the rated output, for example 45kWp on the 30KTLX-G3.

The AC side feeds 3/N/PE 230/400V grids at 50 or 60Hz, with the power factor adjustable between 0.8 leading and 0.8 lagging and active power from 0 to 100%. Maximum apparent power is above the rated value, for example 34kVA on the 30kW model and 55kVA on the 50kW model, which SOFAR describes as prolonged AC overload capability.

Key features

Maximum efficiency is 98.6% on the three-tracker models and 98.8% on the four-tracker models, with a European efficiency of 98.2% throughout. Protection includes reverse polarity, anti-islanding, leakage current, ground fault and PV string fault monitoring, an integrated DC switch and Type II surge protection on PV and AC. An I-V curve scan supports string diagnostics, and smart air cooling keeps the 585×480×220mm unit within its -30…+60°C operating range.

Installation and compatibility

The 36–37kg inverter is mounted upright with 80cm free above, 50cm below and 50cm at each side. Each unit needs its own AC breaker complying with IΔN=0.1A. A residual current monitor is built in; if an external RCD is mandatory, SOFAR recommends Type A or B with 100mA or more. AC line losses should stay below 1%, and the distance from inverter to grid connection point should not exceed 300m.

With an external smart meter on RS485 the inverter limits export on the selling power or on the total power at the connection point; if meter communication fails, output is held at the preset limit, and a hard limit can disconnect the inverter from the grid. Certificates cover VDE-AR-N 4105, EN 50549-1, TOR Erzeuger Type B and G99, and the manual lists CEI 0-21 and CEI 0-16 among the grid standards.

Monitoring and settings

Commissioning and parameter settings are done over Bluetooth with the SofarCloud app, which also handles firmware upgrades; plant data are available on the SofarCloud web portal. Wi-Fi, RS485 and Bluetooth are standard and Ethernet is optional. Several inverters can be daisy-chained on RS485 with Modbus addresses from 1 to 31.

Questions and answers