Without any warning South Africa was plunged into darkness with Stage 4 Load Shedding (rotational load shedding, 4- 5 hours at a time). Load shedding continued for five days.
You can keep your laptop connected to the internet through your smart-phone.
There is an alternative way. Connect your laptop to the internet by using a mobile WiFi router. You can connect up to 5 laptops to the WiFi and once charged this WiFi router will keep you going for 8-10 hours.
The cost is approx R1200. I purchased mine (a M7300 LTE Advanced Mobile WiFi Router) at Matrix Warehouse but there are various retailers selling the device. You will find them on Google.