For those who want to know more about simple pv solar we produce a pdf
There are videos on the Internet that give a good insight into solar pv cells showing they have a similarity with dry cells.
Have look for the tutorials at http://www.solarschoolhouse.net/dmm.html
These are excellent professional films covering a range of pv topics including meters.
Don't forget the parts shown are not exactly what we offer and that a US 'alligator' is a UK 'crocodile' clip.