what the volt for one solar cell?

Answer 1

The forward junction drop for normally doped silicon diodes (which is what a solar cell is, btw), is 0.5V to 0.7V depending on the current draw. The equivalent series resistance of the diode limits the current, therefore limits the voltage to less than 0.6 volts.

To get higher voltages you must put several cells in series.

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Answer 2

Solar Cells try this link:http://www.exo.net/~pauld/activities/physics/solarcellf/solarcell.html
Or this one: http://www.trnmag.com/Stories/2004/120104/Solar_cell_doubles_as_battery_120104.html
Hope it helps.