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Axpert Parallel Installation Assistance


Dean

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Hi,

I need to install two Axpert 5kw units in parallel, I need to understand how to flow works. (unit is connected to Grid and has 10kw of Battery's)

Assuming there is no load shedding

1. Will the solar ever power the load ? or only charge the batteries ?

2. In the case of load shedding would the solar supplement the batteries.

 

Would it be better to implement an AC coupled system (Say 5kw Solar Inverter) on the grid side of the Axpert ?

Thanks

 

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1 hour ago, Dean said:

1. Will the solar ever power the load ? or only charge the batteries ?

In the lower voltage models (max PV open circuit voltage 145 V), the solar charge converter pushes power into the battery. If the battery is supplying the load (in battery mode), then if there is enough solar power, all the load power will come from PV. Any excess charges the battery. If there is a short fall, the battery provides the rest. So in battery mode, as long as the battery is not full, all the PV power goes to loads first, and then to charging the battery.

The problem is that in line (bypass) mode, the loads are powered only from the AC input. Any available solar power will only charge the battery, unless it's full or nearly full (when nearly full, the battery likely can't take all the available solar power, so some will be wasted). If the battery is full, all solar power is wasted. Any utility charging must be done in line mode.

1 hour ago, Dean said:

2. In the case of load shedding would the solar supplement the batteries.

Yes.

1 hour ago, Dean said:

Would it be better to implement an AC coupled system (Say 5kw Solar Inverter) on the grid side of the Axpert ?

An AC coupled system is tricky when there is no grid, e.g. during load shedding. My personal inclination is to say no, don't bother; others may disagree.

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Will the solar ever power the load ? or only charge the batteries ?

It depends on the selected mode. But generaly yes, solar will power the load, while excess power will charge the battery at the same time.
BUT: since Axpert is an off-grid inverter, you cannot power the load from the grid and from the solar at the same time. It's just one or the other. If the solar+battery will not have enough power to satisfy the needs of the load, then the Axpert will switch the load completely to the grid. In such case the solar will be used just for charging the battery.

In the case of load shedding would the solar supplement the batteries.

Yes, if there's not enough sunlight, then the Axpert will use all the power from the solar plus some additional power from the battery.

Would it be better to implement an AC coupled system (Say 5kw Solar Inverter) on the grid side of the Axpert ?

It depens on what are you trying to achieve. If you want to save on electric bill, then it does make sense to have an on-grid inverter (aka solar inverter) on the grid side of the axpert. High-power-demanding loads would be connected on the grid side of the Axpert too. Only the essential loads will be connected to the Axpert. Therefore, during a load shedding only the essential loads will stay powered (running from Axpert's batteries).

If you go this way, it's common approach to connect the majority of your solar panels to the on-grid inverter. Axpert will operate without it's own panels, or you can connect just a small amount of pannels to it - which brings some additional benefits, but like I said, it's not necessary.

 

To be honest, if you want to mix the power from grid+solar and also have some battery backup for the load shedding, the technically best approach is to implement a hybrid inverter (single or paralleled). For a shame, there are some legal issues and obstacles...

 

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39 minutes ago, Youda said:

BUT: since Axpert is an off-grid inverter, you cannot power the load from the grid and from the solar at the same time. It's just one or the other. If the solar+battery will not have enough power to satisfy the needs of the load, then the Axpert will switch the load completely to the grid. In such case the solar will be used just for charging the battery.

@georgelza - a titbit you need to be aware of.

VS say a Multigrid where it can combine solar + batteries + Eskom by using ESS to ensure maximum savings over the lifetime of the equipment.

Edited by Guest
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