It is critical to test for turbulence at least as high as you envisage the tower will be. Some people recommend that you test at least as twice as high as tower because turbulence can cause trouble the top of the blades.

Trees and buildings when inland or at cliff faces when near the sea. Some claim 100 metres minimum distance from trees and buildings and 200 metres from “distinctly different” land form shapes to allow the turbulence to subside. Even over “flat” land many authorities on this recommend a 12 metre high tower as the minimum.

One of the best non technical methods is with a kite. You have streamers tied to the kite string and by taking careful note of how the streamers react you can easily judge how far you need to have the generator placed from the cause of the turbulence.

FAQ Wind Power

 

The vagaries of the wind in different areas, differing loads, land mass heights and potential structures that will cause wind turbulence are major considerations. The closer you are to the sea the greater likelihood of stronger winds. This has its own challenges with wind strengths that can destroy the generator. Turbulence must be considered.

Question 1 Why is wind power more difficult to calculate?

Question 2 How can I get a reasonable calculation on wind turbulence?

Question 3 What is the major cause of wind turbulence?

Question 4 What height should I test for wind turbulence?

No easy answer. In some cases it is the tower with guy wires not able to support the structure adequately. In turbulent areas bearings. Most modern wind generators do not have brushes, replacement of leading edge protective tape in sandy areas is common.

Question 5 What maintenance is required on wind generators?

This is best answered by the weather bureau in or nearest your area.

Question 6 When can I expect maximum wind speed?

This is normally done for you by the manufacturer. A rule of thumb given is for every 1M² of swept area the generator will supply about 230 watts maximum for a good system at a wind speed of 40 Km per hour at sea level.

Question 7 How can we calculate the size of the blades required?

Your wind generator will be about 10% less efficient at that height as the air is less dense. A poor (but well used) rule of thumb is a loss 10% for each 1000 metres ASL.

Question 8 On my property I am about 1000 metres above sea level will this
                   effect my wind generator substantially?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Question 9 I am in an area that only has light winds can I use a wind generator?

Payback on your outlay is the calculation required here to see if it is feasible. If you have say a consistent gentle to moderate breeze (13—16Kph) it may be suitable to have this supplement battery charging with a minimal outlay. It may prove ideal to use a cheaper system if it is only occasional use on the battery. It is not uncommon for the tower to exceed the cost of the actual generator. Make sure you do your sums.

Question 10 When should I have a combination of wind power and other sources?

Unless you have an exceptional site for wind power it is common to have a hybrid site with a combination of say wind, solar and diesel power.

Question 14 What is the best design of wind generator?

This is too hard for a brief answer. Some blade manufacturers spend millions designing the blades alone and it is a point of discussion that this has given the greatest efficiency increases. The type of gel coat and leading edge tape are brilliant. How they attach to the generator is the skill of others. The actual generator is another area that people focused on initially. Which one is finally chosen may simply depend on capital outlay. A choice of either aluminium or fiberglass blades may be a question of site location.

Question 16 What type of power inverter should I use?

Because wind power is unreliable (needs wind) it is unusual to have a wind generator operate by itself without back up. This should be designed into the system. Normally with wind power it is only there to supplement the charging of the batteries so this is not normally as critical as with other systems. If you are operating directly off the wind generator (extremely unusual) then allow for higher power surges as equipment starts up. Ie a 100 watt TV can draw nearly 400 watts on start up and may cause some 300 watt inverters to crash. Make sure that your inverter can handle the brief surges that come with appliances starting up. Make sure the inverter can handle this application.