Hi Victron Community,
I’m reaching out for validation and further insights into a persistent generator synchronization issue I’m facing with my Victron Energy system. My setup uses a conventional generator, and I suspect the root cause lies in the interaction between its transient response and the strict grid compliance requirements enforced by ESS.
My Solar Solution Overview:
- Inverter/Charger: 1 x Victron Energy Quattro 48/8000 (Grid Tied – Single Phase)
- System Control: 1 x Cerbo GX with ESS (Energy Storage System) for Self-Consumption
- Solar Charge Controller: 1 x Victron Energy RS450/100 Solar Charge Controller
- Battery: 1 x 48V Freedom Won 10/8 Lithium-Ion battery
- Generator: 1 x Yamaha EF6600 (5.5kVA / approx. 4.4kW continuous) with 2 x 16A Outlets
- Solar PV: 8 x 345W Sunpower CPV Panels (Approx. 2.76 kWp total)
- Key Load: 0.75kW Borehole Pump (connected to the inverter’s AC output, not directly to the generator).
The Problem: Generator Fails to Sync with Quattro
My Yamaha EF6600 generator is connected to AC Input 2 of the Quattro. AC Input 1 is connected to the utility grid (South Africa) and configured for NRS 097-2-1:2017 (required for ESS Assistant) compliance. When I need to run the generator, I manually disconnect the grid using a main circuit breaker for safety.
Despite the generator showing stable readings at no load (230-232V, 50-52Hz) and even under a separate, steady 1.5kW resistive load, the Quattro consistently struggles or completely fails to synchronize and connect. The generator is confirmed to be running at its full 3,000 RPM when I attempt to switch it through to the inverter.
Key Observations & Troubleshooting Steps:
My VE.Configure settings for AC Input 2 (Generator) are as follows:
- “Weak AC input” is enabled.
- “Dynamic current limiter” is enabled.
- “AC Input Current Limit” for AC Input 2 has been increased to 16A (approx. 3.68 kW) in an attempt to provide more headroom (it was initially 12A).
- “UPS Function” is disabled (which corresponds to “Weak AC” behaviour).
- “Dynamic PowerAssist Factor”: 3
- Neutral-Earth bonding on the generator is handled via a 16A plug to link earth and neutral, creating the first N-E bond at the generator.
The Root Cause: NRS 097-2-1:2017’s Fixed Threshold
I recall that the generator did synchronize successfully in the past when the system’s Grid / Country Code was set to “None”. This crucial observation points to the core conflict:
- When the Grid / Country Code is set to “None” (and ESS is not active), the Quattro operates in a very relaxed synchronization mode, tolerant of fluctuations as it’s not concerned with strict grid-tie standards.
- However, with ESS enabled and NRS 097-2-1:2017 selected for grid compliance on AC Input 1, the Quattro’s overall operational thresholds become fixed:
- The AC Low Disconnect voltage is non-adjustable in VE.Configure, forced by the standard.
- NRS 097-2-1:2017 specifies an under voltage (U<) trip setting of 195.5 V. The Quattro must refuse to connect if the voltage dips below this.
- My conventional Yamaha EF6600 generator, even at full RPM, likely experiences a momentary transient voltage dip below 195.5 V during the critical connection handshake with the Quattro. This dip occurs when the Quattro attempts to pick up existing loads (like the 0.75kW borehole pump, which runs from the inverter/batteries) and simultaneously begin charging the batteries (up to the 16A limit). This sudden, combined load (approx. 0.75kW + 3.68kW + Quattro’s inrush) is challenging for a conventional generator’s transient response. Even with “Weak AC” enabled, the Quattro, bound by the 195.5V threshold, will not synchronize if this dip is too severe.
Proposed Strategies & Questions for the Community:
Given that the Quattro’s 195.5V AC Low Disconnect threshold is fixed by compliance, I’m exploring ways to improve the generator’s stability during connection.
- Strategy A: Pre-loading the Generator with a Direct Inductive Load (My Current Plan)
- Method: I plan to connect and run a 1.1kW compressor directly to one of the generator’s 16A outlets for a minute or two before connecting the generator to the Quattro. This will provide a direct, sustained load to engage the generator’s engine and AVR. Once the Quattro synchronizes, the compressor will be switched off.
- Rationale: A minimum pre-load of approximately 0.9 kW (900W) (20-30% of generator’s continuous output) is generally recommended to stabilize conventional generators. The 1.1kW compressor fits this perfectly and is an inductive load, which helps properly exercise the generator’s regulation. This should make the generator more resilient to the Quattro’s connection transient, helping the voltage stay above 195.5V.
- Crucial Note: Before connecting the generator to the Quattro, I will ensure the 0.75kW borehole pump and any other significant AC loads on the inverter’s output are OFF. This minimizes the initial load the generator has to pick up from the inverter, allowing maximum power from the generator to go to battery charging once synced.
- Question for Community: Has anyone successfully used a similar direct pre-loading strategy with a conventional generator to improve synchronization with a Victron inverter under strict grid code settings?
- Strategy B: The Recommended Solution: Inverter Generator
- Understanding: An inverter generator (e.g., 4kVA to 5kVA minimum, ensuring continuous output of 3.2kW - 4.5kW) is widely considered the most reliable solution. Its ability to produce extremely stable, pure sine wave power, even under dynamic loads, ensures the voltage consistently stays above the 195.5V threshold during connection.
- Question for Community: For those who made the switch from a conventional to an inverter generator for their grid-compliant Victron system, how significant was the improvement in Quattro synchronization reliability?
- Strategy C: Alternative (With Major Caveats): Removing ESS / Grid Code “None”
- Method: Disconnect from the grid, remove the ESS Assistant in VE.Configure, and change the grid code to “None”.
- Rationale: This makes the Quattro highly tolerant of the generator.
- CRUCIAL CAVEATS: This approach completely disables grid-tie safety (anti-islanding) and all ESS functionalities (grid charging, self-consumption). It requires absolute manual diligence to ensure the system is NEVER connected to the utility grid when configured this way, as there’s no automatic protection.
- Question for Community: Has anyone adopted this approach, and if so, what stringent safety protocols do you have in place to ensure absolute grid isolation when operating in “None” mode?
I would greatly appreciate any feedback, similar experiences, or additional insights from the community on these points, particularly regarding conventional generator limitations with fixed grid-code thresholds and optimal operational procedures.
Thank you in advance for your valuable input!
