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Semi Off Grid dilemma

Hi All

Skylla with Quattro setup

I am from South Africa, so some of you will know that except for the constant looming of loadshedding , our electrical grid is in a bad state.
When ever one wants to install a Grid Connected solar system, does not matter what brand or type, Grid Tied or Hybrid, when you connect the input of your inverter to ESKOM( our power utility) in the country side you need to hand in an application first with all plans and designs prior to installation. Even if you do not plan on feeding back to the grid. They are very strict regarding this. Which is understandable, but very frustrating and tedious and can take very long.

When connecting to municipality in a town they are somehow and somewhat less strict.


This leads me to my question, and please direct me to the relevant thread if this has been covered somewhere else. Also do not hesitate to shut my train of thought down if it is not possible or not legal. I am merely pondering with ideas around a problem lots of customers and installers face

Is it at all possible to have the following system :—Grid point transformer is a 50kVa point—

So any loads on the system cannot ex

3 X Quattro 15 KVA 3 phase setup (no AC input)

6 x 250/100 MPPT

40 kw PV array for MPPTs

Fimer or Fronius 50 kVa string inverter on AC output of Quattros

50kW array for string inverter

100

kWh lithium battery bank

3 x Skylla TG 48V in paralell to charge battery bank (specified hours at night or cloudy days)

Cerbo GX

All relevant fusing and isolation and earthing of course.

The important part is an 3 phase automatic on load change over switch.

Once the battery reaches a certain SOC a relay can be triggered to energise a contactor to automatically switch the load back to grid.

Center changeover

It is important that the hybrid and pv inverters are not connected to the grid what so ever.

The only grid connection is the Skylla chargers that feed the batteries if needed.

This way you are not completely off grid witch is fine because the main goal is minimal reliance on the grid without the time consuming and difficult long process.

Perhaps someone gan assist me or advise me if this train of thought is completely off the rails.

Thank you

MultiPlus Quattro Inverter ChargerLithium Batteryoffgridskylla tg
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@Bergmans Trading cc

Why not just keep the loads on the inverters and trigger the skyllas to charge or maintain the batteries? Unless you feel the bank is too small?

The issue with switching back and off the grid is you are relying on the grid to be there when you switch back. Would there be any equipment that gets messed up by the changing over of power?

I would still have the contactor or changeover there though in case the system goes down or needs maintenance and the grid is available to use as an interim.

Not sure the rules and regulations in SA for the setup so cannot answer on that.

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