niren avatar image
niren asked

New Installation for Home


I am investigating options for an installation of solar panels and battery storage/back-up. I live in Johannesburg, South Africa and with the current power challenges this seems like a suitable plan.

However, after consultation with a few experts I am alot more confused as it seems like standard configurations are only being presented.

My questions are:

1. Is it possible to have solar panels installed for the purpose of supplying day time usage only to the entire household. We currently have an average daily consumption of 45kw , about 60% used during the day.

2. As part of the system in No. 1 above, can a battery pack be added to the system that would only serve as back up for essentials like a few plugs and lights.

Currently I have a 1500w inverter with 2 x 400A batteries connected to my lights only. This system has been designed to automatically switch on when there isnt power.

Hope to have receive some help.

Thank you


batterySolar Panelinstallation
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2 Answers
Alexandra avatar image
Alexandra answered ·

@niren It can be a little confusing in the beginning. There are so many options.

As an installer there are many questions to ask. A power audit would need to be done to determine your peak power draws. You know how much power you want to generate that is a good start. But, for example, do you have for example 8000w peaks drawn at once any point during the day? After an audit there may be ways to drop your power consumption a bit and use a smaller system.

This brochure is a good place to start as it gives the information on system setups in picture form.

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Alexandra avatar image Alexandra ♦ commented ·

The answer to both your questions is Yes, it is possible.

60% of 47kwh is about 27kwh - a Fronius Eco can supply that with the correct number of panels to supply during the day.

The Fronius needs grid power to be able to use the Solar panels, so in the event of a power cut it will stop working. I am guessing this is where you want your back up power to kick in. The Eco cannot be coupled to a battery as far as I know.

In the brochure you will see you can use the Fronius after the Victron in the system to make what is called a micro grid to control and to use the Fronius anyway. This is a bit more expensive as there are rules to follow in setup. See the link below

The other option is the Fronius Hybrid - I don't personally lnow much about this one though.

There are videos on all these products on youtube to help you make the decision.

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solarhack avatar image
solarhack answered ·

Any design must factor in if your solution is single phase or three phase and what your peak and average utilization is. Other factors include location of your panels, inverter and type of battery.

If you are want to be grid tied (e.g Grid goes down, the Solar inverter stops supplying power) then a purely Fronius PV inverter solution as mentioned by @Alexandra is the simplest and probably most cost effective to achieve.

If you want to run critical loads when the power fails then you need to add a battery and an inverter/charger. This changes the design quite a bit.

Option 1: AC/DC coupled mix with Grid parallel operation. You could use the Fronius to supply the primary solar power (AC Coupled). A Victron Multi II (1 or more Multiplus IIs linked together to cater for peak load or 3 phase) connected to the battery and possibly its own minimal solar array (Depending on the wiring location of the Fronius) via a Victron MPPT to provide battery backup and enable grid disconnected operation

Option 2: DC coupled system with Grid parallel operation. A Victron Multi (1 or more Multiplus II linked together to cater for peak load or 3 phase) with a battery and one or more MPPT's connected to the solar array as the only source of Solar energy. Victron's newer Smart solar 250 MPPTs could comfortably cater for this sizing

Its important to remember that if you add a battery you need to size your solar arrays to cater for charging the batteries as well as running your house. The different battery types will have different efficiencies, hence affect the sizing of your array.

I suggest you look at some of the Victron links below for more info:

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