Part of the idea is that the producer and consumer of the energy are on opposite hemispheres and at different longitudes. That means when its winter in China, it is going to be summer in Chile. There is also a considerable time difference between the places which helps to supply electric energy via solar power even while it is night in China.
Honestly it's kinda brilliant. With a big enough global network of overbuilt solar capacity you would avoid the problems of the duck curve and weather limitations.
It was hard to build a DC network in 1900. It's easy today with modern power electronics, which Nikola Tesla didn't have. In fact building a DC network is somewhat easier than AC now because phase-matching is unnecessary.
Summary: DC is always a bit more efficient than AC. The reason our grid is AC is because high voltage transmission is much more efficient than low voltage transmission.* But you don't want multi-thousand volt feeds coming into your house, so voltage conversion is necessary. If you don't have power electronics, you have to use magnetic transformers to convert between voltages, and magnetic transformers only work on AC. Thus our electric grid is mostly AC.
Now that we have power electronics we can convert voltages without magnetic transformers, and AC is no longer a requirement except for backward compatibility.
