So i'm running into a bit of a issue with the behavior of the system. I'm pretty sure this is intended but still wanted to ask for options.
I have a 3 Phase system setup (3x Multiplus II) backed by 30kwh lifepo4 batteries which are charged by the MPPT RS inverter. I'm using a EM24 to measure grid power even though my whole house is behind the victron installation.
My grid connection is 3x25A and one of the goals of getting this system is to not have to upgrade to a 3x40A connection which would cost me 700 euros a year. My house is fully electric (no gas connection), electric cooking, electric heating, electric car, heatpump for pool.
This means I have a lot of consumers that if turned on at the same time can trip the breakers. Since i sell power to the grid for 1:1 (untill 2025), the main reasons for the system was 1: UPS functionality, 2: saves 700 euros a year on a higher grid connection bill. 3: Was building a new house, so it was the perfect time to get all the wiring in and 4: Being ready for when i no longer sell to the grid at 100% rate.
I'm generally running a 75% Minimum SoC with a 0W Grid set point. Excess PV is delivered to the grid. Usually in the evening it reaches the minimum SoC. Once it reaches the minimum SoC it seems like input current limit is completely ignored. This means if when the minimum SoC is reached, my breakers can trip when multiple loads are on at the same time.
In my opinion, the input current limit should always be respected, almost as a same priority as grid failure (Since it in 99% of cases leads to grid failure, why else would you configure a input current limit).
The expected behavior for me would be that if a peak load needs to take from the batteries below the minimum state of charge on 1 or multiple phases. It starts assisting on the phases that require it. If there are phases available that have extra capacity left, it can convert AC to DC to supplement the DC requirement for the peak shaving phase. If this is not sufficient (maybe all phases are overloaded) it can take energy from the battery beyond the minimum SoC. Since if it does not do so, theres a risk the grid goes down and having to take from batteries regardless. After the peak load is gone it could top up the batteries back to the minimum state of charge using the grid (not beyond). Since I want the DC coupled solar only to top the battery up to 100% minimizing inverter losses.
Ideally, i'd want to have a minimum SoC for self consumption and a second minimum SoC for power assist to minimise inverter losses. E.g. discharge to 75% for self consumption, then discharge to 50% for peak shaving. If battery is at 50%, still allow peak shaving however when possible use grid to charge back to 50%.
Is what i'm experiencing intended?
Does anyone have any advice or recomendations?