Selecting a site
Looking at nature itself is usually an excellent guide to finding a suitable wind turbine site. If there are trees and shrubs in the area, a good clue about the prevailing wind direction may be get.
Also, when moving along a rugged coastline it may be noticed that centuries of erosion have worked in one particular direction.
Meteorology data, ideally in terms of a wind rose calculated over 30 years is probably the best guide, but these data are rarely collected directly at the specific site and there are many reasons to be careful about the use of meteorology data, as will be explained in the next paragraph.
If there are already wind turbines in the area, their production results are an excellent guide to local wind conditions. In countries like Denmark and Germany where there is a large number of turbines scattered around the countryside, manufacturers can offer guaranteed production results on the basis of wind calculations made on the site.
Pitfalls in using meteorology datas
Meteorologists already collect wind data for weather forecasts and aviation and that information is often used to assess the general wind conditions for wind energy in an area. However, precision measurement of wind speeds, and thus wind energy is not nearly as important for weather forecasting as it is for wind energy planning.
Wind speeds are heavily influenced by the surface roughness of the surrounding area, of nearby obstacles (such as trees, lighthouses or other buildings) and by the contours of the local terrain. Unless calculations are made which compensate for the local conditions under which the meteorology measurements were made, it is difficult to estimate wind conditions at a nearby site. In most cases using meteorology data directly will underestimate the true wind energy potential in an area.
Additional considerations for site selection
The following considerations should be taken also into account when selecting a site:
Look for a view: As already shown in the previous pages, it is preferable to have as wide and open view as possible in the prevailing wind direction and also to have as few obstacles and as low a roughness as possible in that same direction. If you can find a rounded hill to place the turbines, you may even get a speed up effect in the bargain.
Grid connection: Obviously, large wind turbines have to be connected to the electrical grid.
For smaller projects, it is therefore essential to be reasonably close to a 10-30 kV power line if the costs of extending the electrical grid are not to be prohibitively high (it matters a lot who has to pay for the power line extension, of course).
The generators in large, modern wind turbines generally produce electricity at 690 V. A transformer located next to the turbine, or inside the turbine tower, converts the electricity to high voltage (usually 10-30 kV).
Grid Reinforcement: The electrical grid near the wind turbine(s) should be able to receive the electricity coming from the turbine. If there are already many turbines connected to the grid, the grid may need reinforcement, i.e. a larger cable, perhaps connected closer to a higher voltage transformer station. Read the page Power quality for further information.
Soil conditions: Both the feasibility of building foundations of the turbines and road construction to reach the site with heavy trucks must be taken into account with any wind turbine project.