I'm designing a solar tracking module and i need to knwo which motor would allow me to slowly move a solar panel,and tilt it towards the sun's insolation.
Ideally i would have used a linear actuator but it needs 230V mains and also very expensive
So which motor is would suit this application,and also not too expensive DC,Servo or stepper motors.I dont wanna have to use gears to reduce the speed of the motor

 

you need to keep track of position or use sensors to find optimum position.
steppers are cheap, simple and hold position (can be driven blindly using predefined time table).

but what is the torque requirement? how big and heavy the panel is? what about wind? what is your budget? what is the voltage of available power source options?

 

I have available to me at most 5 volts,few stepper motors utilise such a low voltage,also the panel weighs about a kilogram and has dimensions of 180X292X17 mm.

 

You are going to need gearing just for strength against the wind (like Panic Mode said).

Just buy a cheap "DC gearmotor" from ebay or one of the hobby robot suppliers. These have gearing already built into the end of the motor, you can easily get 100:1 gearing, and a 12v motor will still work ok on 5v although it will be slower (which is what you want).

 

Worm gears are good, because the wind can't force the motor to turn like it can with normal gears.