We will use the following hardware to build the circuit:
Arduino Ethernet board (https://www.sparkfun.com/products/11229) or Arduino UNO (https://www.sparkfun.com/products/11021), with Arduino Ethernet Shield (https://www.adafruit.com/products/201)
A solar cell (https://www.sparkfun.com/products/7840)
Two resistors (resistor values should be calculated on the open voltage of the solar cell); take a look at the Building a voltage divider section that follows for the calculation of values and color codes
Some hook-up wires
A 9V DC 650mA wall adapter power supply (https://www.sparkfun.com/products/10273)
DC barrel jack adapter (https://www.sparkfun.com/products/10811)
An Ethernet cable (https://www.sparkfun.com/products/8915)
Also, you will need a computer with an Arduino IDE installed.