Circuit diagram of the project

Arduino Code

//Su-Din Technology  "sun tracking of solar panel"
#include<Servo.h>
Servo s1;
int readPin=A0;
int readVal;
float V=0;

int pos;
void setup() {
  pinMode(readPin,INPUT);
  Serial.begin(9600);
  s1.attach(12);//Control wire of servo to digital pin 12
  s1.write(pos=0); /*when project is initially powered, 
           servo angle=0, to set it  towards EAST.
          THIS IS A RESET OF PROJECT*/
}
void loop()
{
readVal=analogRead(readPin);/*We have to read the analog voltage value at pin A0
                             whic is developed at pin 3 of 555 ic when light falls on LDR*/
V=(5./1023.)*readVal;  
Serial.print(V);
Serial.println("volts");
delay(500);

if(V>3.0)/* I have used a dark activated circuit,
             In my case when torch light falls on LDR
             the voltage at pin 3 of 555 ic is  3.61*/
{    
 pos = pos+5;  /*For each torch light on LDR, 
               servo rotates 5 degree towards WEST*/
 s1.write(pos);    
 delay(100);
 }
if(pos==180) /*This loop is to send back the shaft of servo again towards EAST
              after it has reached WEST*/
{
  delay(1500);
  s1.write(pos=160);   
  delay(500);
  s1.write(pos=140);   
  delay(500);
  s1.write(pos=120);   
  delay(500);
  s1.write(pos=100);   
  delay(500);
  s1.write(pos=80);   
  delay(500);
  s1.write(pos=60);   
  delay(500);
  s1.write(pos=40);   
  delay(500);
  s1.write(pos=20);   
  delay(500);
  s1.write(pos=0);   
  delay(500);
  } 
 delay(500);
}