I'm planning on making a simple solar powered cell phone charger for a demonstration speech in my gen-ed speech class because it seemed like it would be fun at least. The best solar panel I could find for cheap has an output of 6v and 50 mA. My cell phone charger has an output of 5.0v and 700 mA. Now my question is do I need to use a resistor to lower the voltage of the solar panel, and if I do I assume the output current will be even lower, and will it even cause the cell phone to say it is charging? I imagine it would take forever but as long as it says its charging thats good enough. I could probably afford another one and hook them up in parallel if you think that would help. Also, out of curiosity, if you used 4 AA batteries in serial to get 6v, would you need to use a resistor to get it to 5v and, if you did, what would be the output current afterwards? Thank you for your help!