” I’ve always wondered, even with photoelectrics: The photon drives off electrons to generate a current, but the silicon remains. HOW? Where do the “new” electrons come from?”
the electrons move in a closed circle called a circuit, with the photovoltaic effect providing the energy to excite the electrons to move in the closed circuit. no electrons are gained or lost, they are simply impelled to move in a circle, which by definition is a current.