Make your own solar powered robot at home using things you probably already have. Transistors, resistor, capacitor, solar battery and flashing LED are available at any electronic store, if you don't already have them. Solar cells out of calculators work as well, you might want to use more than one since they are really small. If you do, connect the positive wire from each solar battery together. A small motor should be used like the ones in walkmans. Solder everything together and watch it come alive. Put it under a light and let it charge, it should take couple seconds for each burst of energy. Works best in sunlight.
2N3904 Transistor Motor
2N3906 Transistor 2.2V Flashing Green LED
4700 uF Capacitor Solar Cell
2.2 kilo-ohm resistor
Get your self familiar with the diagram below and with the components showed on it. The energy collected by the solar battery is transfered into the capacitor. When the capacitor is charged to a certain level, it lets out a burst of energy into the motor. The bigger the solar cell, the quicker the charge.