Have you ever wanted to monitor how much voltage/current your small PV solar panels are producing? It is easy enough with a multi-meter, but what if you just want to monitor it remotely and log the data on your computer. This high level overview shows a xbee setup remotely logging a PV panels volts/amps to a mac laptop. It makes use of only 10 ohm resistor and 2 ADC ports. No additional microcontrollers were necessary for this example. The PV solar panel is made by Voltaic Systems and costs only $30 (it peaks at 10.2V @ .133A)

http://www.voltaicsystems.com/backpack_solarpanels.shtml (less info)