Lazarus

Earth Neutral fault. So what happens, is when you have load shedding, your inverters neutral looses its reverence to ground, a flouting neutral. and as soon as mains comes back, it creates the earth fault that makes the RCD trip. Bond your inverters output neutral to earth, and rewire accordingly. NB: YOU MUST PUT A NOTE ON THE OUTSIDE OF DB TO INFORM PEOPLE THAT THE INVERTER IS BONDED TO EARTH.

Just as a thumbsuck, to do the approximation properly, one will need the exact power draw from your load, but lets assume its no more than 750W/h
80% of battery (depends on battery type either 80% or 90% max DoD)= 3840Wh
3840/750 =5 hours...Just an approximation.
My nighttime load is about 500W/hr with 3 X fridge's and few lights so, the 750W/hr usage is a good estimate for load shedding usage in a "normal" home.
 

You need to check the spec labels on the equipment for the max Wattage of all your electrical equipment
Without that it becomes a guess at best.
With the fridges you could probably use half of the assumed hours as they do switch on and off.
Once you know the combined wattage multiply it by the amount of hours that you expect to run on batteries and that will be your required kWh. 
Lets assume 600Wh for all this. Then your battery would last around 8hours assuming you run it down to 0% SOC which is not a good idea. Ideally you want to shut it down at 20%.  So 7 hours would be the limit.
Get the Watts first and then you could do a fair calculation.

contact city power
The call centre operates 24/7 365 days a year on 0860 56 28 74 or 0860-JOBURG.
Best of luck

@Lazarus art solar has panels cheaper per rand than that i think. in addition if you're taking to zim then you should consider getting a tax invoice to get vat refund at the border. I've decided on the art solar 310 watt mono solar panel for 1,605 rands (incl VAT), they have a collection point in Joburg.  Am also getting MPP Solar PIP 5048 GK inverter which is basically an Axpert VMIII. Lastly am still working on batteries, at this point it's going to be 4 x 100ah batteries for affordability. 

Hi All
Very new to solar. I will give you details or what I have and where I got them from. please can someone also comment on my choice of batteries.
2 X 325W Poly solar panels from Vital Sat solar Klopperpark Barbara road Isando. 063 133 4022 (R1800 each)
4 x Enertec 105AH 12 volts deep cycle batteries from a guy called Barry 083 267 4585 (R1850 each) Battery world  in Wynberg just outside Alexandra.
1 x 5kva inverter and charge controller from a friend.
Can someone else advise on the choice of batteries that I have. a friend has been using these for some time now and is happy so far. Can you recommend anything else?
I want to add 2 more panels and 2 batteries. any advice will be appreciated.