> flywheel nonsense, just add battery

Flywheels are batteries. If your model is predicated on a particular chemistry of battery, it’s overfitted.

Which requires inverters, which are a huge problem.

Riddle me this, what instantaneous voltage should an inverter target if the grid's at a fault condition? Stated another way, how do you define the frequency of a non-sinuoid?

Careful, get the wrong answer and you get a short and you help melt millions of dollars of equipment, some with year old lead times.

it is no riddle. you are asking questions from 1942. except you put inverter into it. so you either think about current technology or go spark some wires.

you can island and not island at same time. decentralized grid means DECENTRALIZED grid.

every renewable needs battery next to it.

Indeed, not a problem to solve if you have all day to measure it.

The trick is measuring a frequency in the 60s of Hz of a non-sinusoid within a thousandth of a second.

Otherwise you get a short.