Purchasing all the individual components for a wind energy system is a big deal as well as a big investment. There are a lot of things to consider. Often when we are confronted with a situation we are unfamiliar with, the first action we take is to consult an expert in the field. The purchase of a wind system is no different except for one thing - there are few well rounded experts. You may live in an area where there happens to be a good assortment of turbines and experienced installers or you may have to have everything shipped to your site and you and your friends become the "expert installers".
Either way, a wind energy system is not an everyday purchase so it is advisable to know as much information as possible about the components you are considering. The same applies to it's future site location. There are several items that need to be addressed which can mean the difference between a marginal performing turbine and one that comes reasonabley close to expectations.
There are four main points for assessment before committing to that shiny new turbine. Though they seem basic enough there could always be a show-stopper lurking before you can even get off the ground.
This point seems like a reasonable question. Just how much wind will your wind turbine be exposed to and how big are the seasonal swings? For a wind site to be considered a "good" site, it must get enough wind but not too much at one time. Indeed too much wind at one time can be considered a "bad" thing. You may think one day at 0 mph and another day at 40 mph would be an average of 20 mph but there is more to it than that. A 20 mph wind is a nice breeze if it is somewhat steady but extreme high and low speeds will present problems.
So what amount of wind is considered adequate? You can find recommendations of what your average wind speed should be and it is typically in the 12 mph range. This is good information but in our opinion you will want to know more about how that average correlates into useable power. If the application is a grid tie then average wind speed may be more easily applied but for the off grid system there is much more to consider.
This is the one problem that will present itself if you live in a subdivision with lots under approximately one acre in size. To get a turbine out of turbulent air is necessary to its longevity and energy output. A taller tower will typically mean a correspondingly larger footprint. There are also noise and yes, asthetics to consider. A 10,000 square foot city lot would probably be a hard sell to neighbors who are not interested in a hulking monstrosity gawking down into their backyard. You will have to apply some common sense in this part of the planning.
Many communities have not yet had to deal with small wind turbines so there may or may not already be zoning or covenants addressing the issue. If there are no specific laws governing a wind system, look next at maximum building or tower height. This could be a problem if you are restricted to 40 feet or less since that would hardly provide adequate clearance anywhere except in a treeless, open field.
Even with a site survey, remember that wind patterns can change from year to year. We have personally observed substantial changes over time at each location we have lived at in Alaska. The patterns seem to repeat over the long term but one "windy" winter has not necessarily meant the next one will provide equal wind potiential. Counting on consistient wind is a nice thought but just be sure to have a backup plan!
Once you have given careful consideration to these four beginning steps, you will need to proceed to the next two steps to get a feel for the wind quality of your location and estimate just how tall of a tower will be required for your installation.
The next step would be to evaluate your site to verify that you have a viable wind site. After determining the location where the tower will be placed, this will allow you to measure the height of the surrounding objects to get an approximate minimum tower height. The section on Tower Height will offer some criteria for getting your wind turbine into smooth, turbulent free air.