Sungrow SG4.0RT Inverter, 4kW on-grid three-phase

This is the equipment that converts the power produced by the panels into the electricity used by household appliances and sends the surplus into the grid. It is a grid-tied model, without a battery: it works as long as the grid is present and reduces your bill by using your own energy on the spot. It is compact, light and designed to be installed quickly, with connectors that are simply pushed into the socket.

At 4 kW output power it accepts up to 6.0 kWp of panels, i.e. an oversizing of 1.5 times: instead of matching the panels exactly to the inverter's power, you can install more and gain output in the morning, in the evening and in the cold months, as a guideline, depending on the location. The two MPPT trackers allow two groups of panels on different slopes, and the start-up from 180 V means the system comes into operation early. At about 18 kg, installation is done by a single person, and the IP65 enclosure allows placement indoors or outdoors. It also has a PID recovery function, which at night reverses an electrical phenomenon that would, over time, reduce the output of the panels. Monitoring is done through the iSolarCloud app, where you see the daily output and any warnings.

Rated AC power 4.0 kW, three-phase output 3/PE, maximum recommended PV power 6.0 kWp. DC: maximum voltage 1100 V, rated 600 V, start-up from 180 V, MPPT range 160-1000 V, 2 trackers with 2 PV inputs. Maximum efficiency 98.20%, European 97.00%. IP65, weight about 18 kg (RT series), push-in connectors. Protections: integrated DC switch, DC reverse polarity protection, residual current protection and PID recovery function. RS485 communication and WiNet-S module with WLAN or Ethernet, commissioning and monitoring through iSolarCloud.

Who it suits

Suitable for a house with a three-phase connection and a roof that fits 4-6 kWp of panels, where a simple inverter is sought, easy to install and to follow from your phone.

Terms explained

• PID recovery: PID is a slow degradation of the panels caused by voltage differences relative to earth; the recovery function usually acts at night and brings the panels back to spec, protecting output over time.
• DC oversizing: Installing a panel power greater than the inverter's power, here 6 kWp on 4 kW; energy is gained during the weak hours and in winter, with a slight limitation at the peak of sunny days.
• Residual current: A current that escapes from the installation towards earth, a sign of faulty insulation; the protection detects it and shuts down the installation before it becomes dangerous.

Technical specifications

Recommended applications

• Small residential photovoltaic installations, of 4-6 kWp, with a three-phase connection
• Household prosumers who want a compact inverter that is easy to install
• Roofs with two different orientations or inclinations
• Systems where the PID recovery function for the modules is necessary

Technical details

Specifications confirmed from the manufacturer's datasheet

Sungrow SG4.0RT is a three-phase grid-connected photovoltaic inverter from the RT series for residential and small commercial applications, with a rated AC power of 4.0 kW and three-phase 3/PE output. The maximum recommended PV power is 6.0 kWp, which means the inverter supports a DC oversizing of 1.5 - useful for better output in the morning, in the evening and in the cold season.

The DC side accepts a maximum voltage of 1100 V, with a rated voltage of 600 V and a minimum start-up voltage of 180 V; the MPPT tracking range is 160-1000 V, and the inverter has two independent MPPT trackers, with several string inputs, for roofs with two orientations.

The maximum efficiency is 98.20%, and the European efficiency 97.00%. The enclosure has IP65 protection, suitable for indoor or outdoor mounting, and the compact construction of the RT series (approximately 18 kg) and the push-in connectors reduce installation time.

The safety features include an integrated DC switch, DC reverse polarity protection, residual current protection and the PID recovery function, which counters the potential-induced degradation of the modules. Communication is done through RS485 and through the WiNet-S module, which offers a WLAN or Ethernet connection, with monitoring and fast commissioning through the iSolarCloud app.