question

This needs knowledge about your system and local laws in your area, you should ask a experienced local installer about that.

The community is not the right place to discuss such system designs.

Hi Matthias, thanks for your input - I am an experienced local installer but new to Victron! I understand the laws and carry out G98 99 regularly. In this situation it is quite basic - not allowed to connect any inverters capable of generating more than the currently installed one.

As far as I have seen Victron is the only brand that would allow me to DC connect loads of solar as the MPPT are seperate. With most other Hybrid inverters I would be limited to max 15kw on a 10kw inverter.

For example in one building there is a Sunnyboy 10KW 3 phase.
I would propose to replace with 3 x Multiplus 3000. This is perfectly acceptable to the District Network Operator as the total capacity is not increasing. However - with more PV capacity and batteries I would be able to run much closer to the 10KW much more of the time.

I have started the Victron online training but thought someone might have done something similiar for the same reasons.

@Tom Chester what you say makes sense and would seem like a reasonable way to add power to the system without increasing the export capability.

It is as you describe. Since the inverter capacity is 3 x 3Kva, the interface to the grid (and thus your maximum injection rate) is limited by this power. However, on the DC side, you can buffer as much energy as needed by oversizing. If you install a bunch of MPPT's, and battery capacity to capture it all (enough parallel batteries to accept all the incoming current), you can size it as big as you want.

However, your ability to use all that power remains bottle necked by the 3 x 3kva inverters (that can only deliver 7,5kw cont. power).

When sizing your system, you have to know what your peak loads are going to be. Your inverter (as well as your batteries) need to be able to provide those peak loads, otherwise you'll still be using additional grid power.

Second you need to have an idea of your daily power consumption to determine how much solar power you actually need to generate and capture in your batteries.

Also think about the timing of your power consumption. If some big loads are running continuously throughout the day, you don't need to provide as much batteries to capture this PV energy as it is used immediately by the load.

I am assuming you are doing this to maximise the SEG/FIT revenues? I think you will need to make a new application to the DNO if you are adding battery storage, and they might not take kindly to a system where you are deliberately exporting from the battery unless you can show that the exported power can only come from the solar PV and not from importing at a different time of day.