How to set up a Deye tetraphase inverter on a 3x220V network without a neutral conductor

Adapting a hybrid solar inverter to the specific characteristics of the local electricity grid is essential to ensure the performance, safety and durability of your photovoltaic installation. In Belgium, some areas still have three-phase 3×220V grids without a neutral (known as IT – Isolated Terra grids). These particular configurations require specific inverter settings to ensure optimal operation.

The good news is that the latest generation of Deye hybrid inverters have this feature built in. In this in-depth technical guide, Wattuneed explains the complete configuration procedure and the protections to be implemented, and directs you to the solar kits, lithium batteries and three-phase inverters that are compatible with this type of grid.

Understanding IT networks: when and why configure 3×220V without neutral?

IT (Isolated from Earth) networks are distinguished by the absence of a direct connection between the neutral and earth. This configuration, still found in some industrial installations and older Belgian homes, has specific characteristics:

• Phase-to-phase voltage (LL): 220V between two phases.
• No neutral conductor: pure three-phase 3-wire system.
• Reinforced insulation: better service continuity in the event of an insulation fault.
• Adapted protection thresholds: requires phase-to-phase (LL) settings rather than phase-to-neutral (LN) settings.

Without the appropriate configuration, a standard inverter may trip unexpectedly due to a fictitious voltage fault or erratic network tracking with micro-cuts.

"Correctly configuring the inverter in IT mode avoids 90% of the grid compatibility problems encountered in three-phase installations without a neutral."

Step-by-step configuration procedure (3×220V IT network without neutral)

Step 2: Selecting the IT network standard

This step is crucial: it activates the phase-to-phase (LL) operating mode required for networks without neutral.

1. Main menu → Advanced Settings → Grid Setting → Grid Selection.
2. Set Grid Frequency: 50 Hz (European/Belgian standard).
3. Grid Level: use the ↓/↑ keys to select LL: 230 VAC.
   • ⚠️ DO NOT select LN: 230 VAC (standard phase-neutral mode).
   • ✅ Confirm LL: 230 VAC (phase-to-phase mode).
4. Enable the IT system – neutral is not grounded option: Enable.
5. Confirm with Enter and wait for the inverter to restart.

EMS optimisation: Time-of-Use, zero injection and Smart Load

Time-of-Use (TOU): smart tariff arbitrage

Program the charging and discharging of your solar battery according to off-peak/peak tariff bands:

• 00:00 – 07:00 (off-peak hours): maximum battery charge from the grid (low tariff).
• 07:00 – 22:00 (peak hours): priority battery discharge to power domestic loads.

Potential savings: With a tariff differential of £0.15/kWh (off-peak/peak) and a 10 kWh battery, possible daily savings of £1.50, or approximately £547/year.

Economic analysis: profitability of a hybrid system in an IT network

Initial investment: Approximately £9,500 including VAT for a complete 6kWp installation with 9.6kWh of storage.

Return on investment: £11,000 ÷ £2,165/year = ≈ 5.1 years.

FAQ – Frequently asked questions about IT configuration

1. Can my Deye inverter operate on a three-phase network without a neutral?

Yes, absolutely. Deye three-phase inverters in the SG04LP3 and SG05LP3 series natively support IT networks (3×220V without neutral) by activating IT system mode – neutral is not grounded and selecting LL: 230 VAC.

2. Does zero-export mode work in an IT network?

Yes, perfectly. Simply install an external three-phase CT meter on the mains input to keep the injection below the programmed threshold (e.g. 3.68 kVA in Belgium).

📞 Need help? Contact us:
Wattuneed – Rue Henripré 12, 4821 Andrimont, Belgium
+32 87 45 00 34 – info@wattuneed.com