Photovoltaics or PV are the same what we call as solar panels. They absorb energy from sunlight and convert it to electrical energy. Electricity produced on these PV cells are then stored in a battery. Later with the help or an power inverter this electrical energy is used in homes or other buildings to serve the electrical needs. PVs won't run out of electrons. Wear and tear may affect the functioning of photovoltaic cells but generally it doesn't affect the efficiency of panels or cells.