Hi all,

I am wondering what is the purpose of the IC in the modern inverters

I see many posts talked about comparing batterh gnd and output neutral but I don't understand why

Can any one explain?

Thanks

32 minutes ago, Adnano said:

Hi all,

I am wondering what is the purpose of the IC in the modern inverters

I see many posts talked about comparing batterh gnd and output neutral but I don't understand why

Can any one explain?

Thanks

You should not connect an inverter's neutral to the grid's neutral because it creates dangerous "ground loops," causes "nuisance tripping" of safety devices (like RCDs/Earth Leakages), violates electrical codes (by converting TN-S to TN-C systems), and introduces phantom voltages (like 60V) onto the ground wire, making the system unsafe and potentially damaging equipment. The neutral-ground bond should only happen at the main service panel, not at the inverter, allowing the inverter to act as a floating source when off-grid and correctly sense faults. 

Key Dangers & Problems:

• Ground Loops & False Trips: Bonding neutrals at both the inverter and the main panel creates multiple paths for current, causing earth leakage (RCD) breakers to trip unnecessarily and creating dangerous potential differences.

• Violation of Standards: It effectively turns a safe TN-S system (separate Neutral & Earth) into a TN-C system (combined), which is illegal in many places and invalidates Certificates of Compliance (CoCs).

• Phantom Voltages: Unbonded inverters can have "ghost" voltages (e.g., 60V) between neutral and ground; bonding them connects these real voltages to your earth, making the ground wire live and dangerous.

• Harmonic Distortion: A solid neutral connection interferes with the inverter's ability to detect grid issues, as harmonics can flow through it.

• Equipment Damage: Some inverters are not designed for this and can burn up or malfunction when the neutral and ground are bonded incorrectly, notes a Scribd article. 

Correct Practice:

• Bond at the Main Panel: The neutral-ground bond (N-G bond) belongs only at your main distribution board, where the grid's neutral and earth are bonded to the main earth spike.

• Inverter as Floating Source: When off-grid, the inverter acts as a "floating" source, similar to a generator. It should only bond its output neutral to an earth spike (or the house earth via a relay) when it detects it's truly isolated from the grid, as per its design.

• Use Transfer Switches: Use an automatic transfer switch (ATS) that moves the neutral alongside the live feed to switch between grid and inverter power, maintaining the correct bonding point at the main panel.