I agree that a 100% renewable grid is not economical at this time. Nor is 90%, nor 80%. The question is where the threshold lies for the maximum amount of renew

I agree that a 100% renewable grid is not economical at this time. Nor is 90%, nor 80%. The question is where the threshold lies for the maximum amount of renewable generation we can accommodate while maintaining reliability and delivering power at an economical price for consumers. That number is going to vary in different grid systems based on the size of the balancing area, the strength and resiliency of the transmission system and amount of storage available. Balancing areas with large amounts of hydro-storage will be able to accommodate more renewables, as will those that connect 10s of thousands of MW or more. This isn't about physics and math. It's about SA being a very small grid where contingencies (both transmission and unit trip) dominate reliability planning. There are grids operating with the same level of renewable penetration as SA or more that have never experienced load shedding. SA could accommodate perhaps one large nuclear power plant. And then the entire system design would be dictated by unit tripping contingencies. The cost of planning the system to prevent load-shedding when a 500+ MW unit trips at that plant would be massive. Nuclear is not a panacea for system security. Please don't generalize the problems of a very unique and small system to the rest of the world. SA has unique challenges as a vast and sparsely populated region that don't exist in Europe, Asia or even most of North America. ERCOT has run with 40% wind penetration on a 44 GW system, and they've done it cheaper than anyone can build nuclear today.