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Are there any? I can't imagine how one would harvest kinetic energy without moving parts...

This is the closest thing I'm aware of, but I'm not educated in this field:

The "grass" generates electricity when it waves back and forth in the wind.

An electrical generator is 100% solid state up to the output wire (battery storage may not be). Not sure what your question is.

Except for the spinning parts you mean? Those bearings run out and need maintenance.

Ontopic: There are some preliminary design for electrostatic wind energy converters: see for example http://www.wired.co.uk/article/bladeless-wind-turbine-ewicon

I think "solid state" is being used as meaning "no moving parts".