Photovoltaic power generation system is generally divided into single-phase grid-connected power generation system and three-phase grid-connected power generation system, in general, the system less than 5KW is generally used single-phase grid-connected, more than 5KW is generally used three-phase grid-connected system, then, what is the difference between three-phase photovoltaic inverter and single-phase grid-connected photovoltaic inverter?
First of all, let's understand, what is "phase"? "Phase" refers to the three-phase firewire (A/B/C or L1/L2/L3), the transformer generally output is three firewire and a zero wire (N wire), some will also lead to a ground wire (PE).
So what is single-phase, three-phase? What is the voltage of each type of electricity used in daily life?
A. Single-phase inverter
Single-phase inverter is to convert the output AC voltage to single-phase, such as AC 220V or 230V.
Single-phase inverter interface has three jacks, respectively labeled "N" "L" "PE":
L for the fire wire (marked with the letter 'L' Live Wire) with red or brown wire;
N for zero wire (marked with the letters 'N' Neutral wire) with blue or white wire;
PE indicates the ground wire (marked with the letter 'E' Earth) with yellow and green wires.
Two, three-phase inverter
Three-phase inverter is to convert the output AC voltage to three phases, such as AC 380V or 400V, three-phase power is composed of three AC potentials with the same frequency, equal amplitude, and 120° phase difference in turn.
The interface of the three-phase inverter has five holes, in order A, B, C, N, PE. A phase is yellow, B phase is green, C phase is red, N means zero line, with blue or white line; PE means ground line, with yellow and green line. A, B, C may also be L1, L2, L3; U, V, W.
The simple summary is: 5-hole interface, 400V voltage level.
In the installation of three-phase inverters, often heard of three-phase four-wire, three-phase five-wire, after the "phase", the following "line", the following common types:
Single-phase two-wire: a fire wire + a zero wire.
Single-phase three-wire: a fire wire + a zero wire + a ground wire.
Three-phase three-wire: three fire wire, more than 10KV lines.
Three-phase four-wire: three fire + a zero line, mainly 380V/220V (400V/230V) low-voltage lines, with a working zero line N and as a grounding protection line PE, can be called the protective neutral line, with NPE, for the basic balance of three-phase load power places.
Three-phase five-wire: three fire lines + a zero line + a ground line, the working zero line N and the special protection line PE strictly separate power supply system, used for higher safety requirements, power-using equipment requires grounding places.
In general, single-phase grid-connected inverters are connected to single-phase two-wire and single-phase three-wire grid lines.
Three-phase grid-connected inverters are connected to three-phase four-wire and three-phase five-wire grid lines.
In the face of choosing a three-phase grid-connected PV inverter or a single-phase grid-connected PV inverter, you need to choose according to the actual power generation situation and needs.
