[syntaxing]

Piezo actuators are solid state devices, though the definition can get hazy. The biggest issue with heat pumps like TECs is that you’re always paying the entropy price so you need more energy to move energy. But you also need a thermal sink somewhere to remove the generated heat. Ends up being a vicious loop for electronics.

[wkat4242]

The actuator perhaps but the wiggling thing attached to it that moves the air? I don't think that's solid state? If it were you could even call a fan solid state.

[wkipling]

On a macro scale it is solid state. Ultimately everything is vibrating when you look close enough.

[postalrat]

The piezo is a single piece while a fan has at least two.