What is the approximate open-circuit voltage produced by a fully illuminated silicon photovoltaic cell?
Why A silicon solar cell is essentially a large-area PN junction; when light frees electron-hole pairs, the junction field separates them and builds a forward voltage that self-limits at roughly half a volt. Typical open-circuit voltage for a fully illuminated silicon cell is about 0.5 to 0.6 volts, which is why panels string many cells in series to reach 12 or 24 volt levels.
Watch out The 0.7 volt choice is the forward voltage drop of a silicon diode when it is conducting current, not the open-circuit output of an illuminated cell, and 1.1 volts is really the silicon bandgap energy in electron volts, while 1.5 volts is an alkaline dry cell.
Silicon cell: half a volt each, so ~36 cells make a 12 V panel. 0.7 V is a diode drop, 1.1 is the bandgap.