solar street lite system

i need the control circuit of solar street lite system

Isn't your instructor expecting you to at least put some effort into designing it yourself?

well for starters you can atleast think of how you gona work it out!!
the simplest approach is to use the solar cell as a sensor itself.when the o/p stops coming then you can turn the light on.ofcourse easier said then done. give it a start and people will be more then obliged to help you.