Nope, solar cells are solid state devices. ;)
except for the fact that you actually want a grid tied interia component for stability.
So even in that case, you still tangentially need a “spinning mass” even if emulated in software with how it supplies energy to the grid. It’s still technically there.
that’s still just inertia though…
Now just using the complicated AC coupling of DC energy, through complex electronics…
All when you could just, big motor with massive mass spinny real fast like, and then when the mass starts spinning the motor, it makes power.
Mechanically, it’s probably both cheaper, and more cost effective to just use a flywheel, which is literally going to be an inertial system.
Honestly the easier way to switch from solar DC to grid AC is to just have a flywheel between the grid and the solar power plant. It might not be as efficient as a capacitor bank or super capacitor bank but it’s dead simple to implement and it’s extremely reliable.
ideally you wouldn’t want it in between, but beside, you would implement it as a “frequency smoothing” device, along side production, probably at a factor of regulation specified amounts.
Modern solid state conversion is very efficient and highly effective, it’s just not great at the inertial problem, though it can be mitigated. It’s just not as clean.