Solis Seminar, Episode 27 : How does a single-phase inverter connect to split-phase grid

Background

In some special countries and regions, the grid structure involves split-phase grid, but if there is no split-phase inverter when installing PV system, can the conventional single-phase inverter be connected to the grid? What problems should we pay attention to? We will share them with you in this Solis seminar.

About 120V/240V Split Phase

120/240 Vac split phase is a type of single-phase three-wire mid-point neutral power distribution system commonly found in America with a standard phase-neutral voltage of 120 Vac for residential and light commercial applications. The phase to phase( Live to Live) voltage is 240Vac for heavy industrial loads such as compressors, fridge, and pumps. Because of the 120-0-120 voltage configuration, it is also sometimes referred to as dual-phase, 2 phase / two-phase or even mistakenly, single-phase 220Vac.

How to use a traditional single-phase inverter in a split-phase grid system?

Usually, customers in some regions will mistake 120/240VAC for single-phase 220VAC grid. Therefore, the PV grid-connected inverter purchased is single-phase inverter (L+N), which will cause trouble in the installation process, but do not worry about it.The L+N structure single-phase inverter can still be used in 120V/240V split phase power grid.

Wiring topology

Figure 2 wiring topology

As shown in Figure 2, we only need to connect the Line and Neutral wire of the inverter with the two Lines of the Split Phase grid, and then the PE wire of the inverter is connected with the Neutral of it.

About Setting

This wiring method does not need any special setting of the inverter, only need to set the local grid standard.

Main Menu→Advanced Settings→Password 0010→Select Standard→Select Standard Code

→Save & Send；

NOTE：

In this system,when using the zero injection function, please pay attention to the CT line entry method, which is different from the conventional thread method. We need to loop the L2 cable on the CT, which shown in Figure 3

Figure 3 The wiring topology of zero – injection function in split – phase grid

Summary

Single-phase inverter can be connected to the split phase power grid. Of course, this is an emergency solution under abnormal circumstances. For the split phase power grid, the best suggestion is to use the grid-tied inverter of Solis US version.

Solis is one of the world’s largest and most experienced string inverter manufacturers with a global network of service teams.

If you have any other questions, you can contact Solis support engineers or go to www.solisinverters.com/aftersales.html