We have discussed many projects related to solar energy and we are going to discuss many more in next few months.In this post we will see how we can use sun light in automobile.  
Though this project has been implemented by many companies, it would be great to build one for yourself in a lab or as your final year project.When I was thinking about this project , I thought it would be great if we can build it as a extension of rain sensor wipers project idea. 
It is very easy to build and needs very few components. Rain Operated Motor consists of conduction sensor(Tough Sensor) circuit, Control Unit, Wiper Motor and Glass Frame.
Concept:
We all know that wipers need electricity to move and this electricity has been supplied by battery inside a car. So, to move wiper using solar power, you just need to supply electricity to this battery or some smaller battery(if you want independent system) using solar panels.
Older System

Wipers <—–Battery<—–Car Engine
Solar Powered Wipers
Wipers<—–Battery<——-Solar Panels<—–Sun Light
To optimize performance , you can use rain sensor wiper as shown in this video:

Related Projects:
Mechanical
Physics
Solar Energy