Less then 99% means not having a working fridge for 3-12 hours or more in 30c heat so there went all your perishable foods. It means no lights in the house will work. No cooling or heating of any kind. No computers. No phone. None of your other random applicances will work either. None of the stuff you use to navigate a city like street lights will be working. Of course it can be mitigate with a generator or an expensive battery bank with solar panels provided you don't have a large enough load. Of course solar panels only work during the day so if the outage lasted into the night then you better hope to have a large enough bank to power all your essential equipment.
Suffice to say, less then 99% available is pretty terrible. You should come down and talk to a South African.
The historical trend line https://ourworldindata.org/battery-price-decline, that those involved in this business seem optimistic that this will continue into the future, and that I am not aware of any technical barriers preventing that (even with no technological breakthroughs it seems likely that we would continue to see declining costs for some time even just due to economies of scale).
Suffice to say, less then 99% available is pretty terrible. You should come down and talk to a South African.