Solar backup system, advice needed
I think there are two levels of Battery backup here, First you can do a full move into Solar. in which case you would need a LOT of changes to your current setup (energy efficient devices, LED Light Bulbs, Solar Geyser, LED PC Screens, LED TV, Alternatives to tumble-dryer, gas stove etc. )  I dont think its as easy as spending lots of money on a solar implementation. 

In terms of your PC Issue, a nice, relatively cheap option would be to only backup your pc equipment. I am in the process of doing that with my Modem, Router, Switches (all 9v). Laptop and two Screens (LED 19v). I will use a simple DC Charge controller and Fail-over circuit (HERE) and then will have a LION batterypack made up specifically for the two 19v screens, The laptop will just get an extra-size battery

Otherwise the alternative is just to go the route of a large UPS, But I am trying to use source voltage current to avoid the need for a pure sine wave converter (since my pc and monitors are really sensitive to different wave patterns) - for that reason, I would like to get everything on DC... 

This is not an implemented solution, but I am in the process of designing (also in RSA). so a good (cheap) solution would be great