What is the approximate open-circuit voltage from a fully illuminated silicon photovoltaic cell?

A single silicon photovoltaic (solar) cell generates an open-circuit voltage of approximately 0.5 to 0.6 volts DC when exposed to full sunlight. This is a fundamental physical characteristic of the silicon PN junction used in standard solar cells. Because 0.5 VDC is far too low to power most amateur radio equipment directly, manufacturers wire multiple cells in series to create higher, more practical voltages (such as wiring 36 cells in series to get around 18 volts for a 12-volt charging system). When trying to remember this value, it helps to recall that a silicon solar cell's voltage is very similar to the typical forward voltage drop of a standard silicon diode.