Greetings from Australia! I’m hoping someone can help me troubleshoot an issue with my setup.
I have an Energy Storage System (ESS) consisting of 3x Multiplus-II inverters configured in parallel, along with 20kWh of batteries, all connected to the grid. The system is complemented by 13kW of solar PV, distributed across 3 grid-tie inverters: two of these are connected to the AC-in of the Multiplus-II system, while the third is connected to the AC-out.
Recently, I installed a 20A EV charger, which is also connected to the AC-out of the Multiplus-II system. Under normal conditions, this setup works well—our solar PV generation typically covers 100% of the loads, including charging the EV and powering both houses on the site.
The issue arises because we are on a time-of-use electricity tariff: electricity is cheap during the day but becomes very expensive in the evening. Over the past few days, we’ve had significant cloud cover and rain, resulting in insufficient solar generation. As a result, we’ve had to charge the EV from both the grid and the 20kWh battery bank using the scheduled charging feature.
This situation has led to an unexpected problem: with the EV charging, battery recharging, and the regular house loads, we’re exceeding our 50A grid supply limit, causing the breaker to trip.
Initially, I thought this was a configuration issue, so I checked the settings in the Victron ESS. The system is configured with a 45A limit for the “Whole Site” in the ESS settings. However, during periods of heavy load, the system doesn’t seem to respect this limit—it appears to only regulate the AC-in feed of the Multiplus-II system. This means that it’s still possible to exceed the grid connection limit, as it doesn’t seem to account for the combined load of the AC-out side, grid-tie inverters, and battery charging.
From my understanding, the ESS should prioritize managing loads and adjust the battery charging rate to ensure the grid connection limit isn’t exceeded. (i.e automatically pause/slow down the battery charging as needed.
Is this behavior expected, or is there something I’m missing in the configuration? Are there additional settings that can ensure the system manages the “Whole Site” load effectively to stay within the grid limit?
We’re also planning to add a second EV soon, which will further increase the load, particularly during the cheap electricity period. I want to ensure the system can handle this increased demand without repeatedly tripping the breaker.
Any advice or suggestions would be greatly appreciated! - Although I suspect we might have to get the supply to the property upgraded.
