No. 1 - what is the annual average wind speed?

Annual speed is near to 10 to 8mph i want to make this turbine for my house

2. What are the local power companies' criteria for microgeneration that feeds their network?

3. How high it is off the ground. The last thing you want are the blades hitting the ground.

its more than 12 feets.is there any formula to calculate dia. of turbine

At 8 m/s, a turbine receives about 314W/sqm.

Multiply by your turbine efficiency (usually ~30%, but often only about 25% for small units. Max theoretical is the Betz limit of 65%). Then compensate for your generator and control system efficiency.

Power varies with the cube of the wind speed.

You need to decide on horizontal or vertical axis wind turbine.

Vertical axis has simpler tower requirements but usually lower efficiency. Some designs need to be rotating before they can start to work and are not self starting. An exception is the Savonius type, but it has lower efficiency.

Small sizes are easy to make and can be quite cheap.

An advantage of the Savonius is that it is rotates comparatively slowly. Max peripheral speed is below max wind speed.

In larger sizes the Savonius is expensive because more material is used.

You can make a Savonius out of a 205L steel drum. Details can be looked up on the net.

Horizontal axis turbines are faster running and need to swivel to align to the wind. They tend to be more efficient than VAWT (I'm talking here of small units, not the large MW size ones).

A vane used to align the turbine to the wind can be swung to "feather" it in excessively windy conditions, removing the need for an overspeed brake.

You need to get some idea of the reliability of your local winds at the height at which you plan to mount the turbine.

A "wind rose" can be plotted giving direction, speed and percentage of time at that speed.

A weighted average speed can give you the potential output for your site.

The "dead" time per year and the maximum time of wind below generating speed in relation to your requirements tells what energy storage you need.

Clearly there is a lot of data collection and number crunching before you decide:

(a) Is wind power feasible for this site?

(b) What type of turbine should I use?

In addition, you need to find out whether you can use it to supplement the local supply, sell surplus to the local authority and buy to fill in your shortfalls or whether you become completely independent.

Sounds like you have some good fun ahead of you.