Wind turbine technology has become more efficient and affordable in recent years and a whole mess of new models has flooded the market. With so many options available, the purchasing decision can be daunting. This article identifies and defines the characteristics that will help you pick the right wind turbine for your situation.
Once you’ve explored these characteristics check out our list of the top five low wind speed turbines and this primer on the market, economics and uses for small wind turbines.
Wind Speed
Rotor diameter defines swept area, which is the major determining factor in how much power a turbine can generate. The larger the diameter, the more power will be generated. Small wind turbines generally run in the 8 to 56’ range.
When analyzing different models’ specs do not dwell on peak output since different manufacturers use different wind speeds to make their assessment, making it an unreliable gauge. Instead, focus on monthly energy output in kWh to estimate how much electricity you can expect a model to produce in a month.
Cut-in / Cut-out
Once you know the average wind speed for the site you have chosen, use that information to find a turbine that is right for you. If your site gets minimal wind, have a look at models designed to operate in low wind speeds and with a low cut-in (the wind speed that the turbine starts generating power at). If you’re blessed with lots of wind, pay particular attention to cut-out, (the maximum wind speed a turbine can handle — any additional increases in wind speed won’t yield higher power).
Upwind or Downwind
Most models on the market are upwind machines (blades on the windward side). There is no clear advantage between the two designs. Look at the specs of each individual model to accurately assess its performance.
Horizontal or Vertical Axis
Horizontal axis wind turbines (HAWT) are the dominant technology on the market because, in general, they are more efficient than vertical axis wind turbines (VAWT) — 35% to 30%. This is partly due to the VAWT’s less efficient design in regards to generating lift. Part of the reason also has to do with the extra stress that affects the interior of the turbine, the weakest part of a VAWT, which results in manufacturers increasing the strength (and weight) of their product. For HAWTs, the middle is its strongest point so needs no extra reinforcement.
Noise
Remember the NIMBY (not in my backyard) factor. You don’t want to go buy and install a turbine to have an irate neighbor come knocking at your door the next day demanding you to turn the volume down. Avoid the problem before it’s too late. If you are siting the turbine close to neighbors, have a look at the many models on the market that claim low noise operation.
Vibration
If you’re mounting your turbine on your roof, consider the vibration factor. This concern becomes particularly important if anyone in your home is a light sleeper. Once it’s up, it’s up. If you plan on selling your home and leaving the turbine behind, think about the impact a vibrating turbine will have on your sales price.
Warranty
Are you handy with repairs should the need arise? Do some research on the Internet and by asking the dealer how often the model breaks down or if it has a high return rate. Does the warranty cover parts and labor, and does it include crane costs, if that is necessary? How much do you feel like gambling that your model won’t break down? Once you’ve assessed all these factors you’ll have a better idea of how long a warranty you feel comfortable with.
Installation and Maintenance
Is this a DIY installation or would you need a professional installer to put it up? Flip through the operating manual to see how easily understandable it is. Will you be able to repair this on your own? Ask how easy it is to obtain spare parts now as well as years from now. Also, ask the dealer if they offer installation, maintenance, and tech support help to customers?
Foreign or Domestic?
If you find a foreign model that you like, consider the long-term implications of the purchase as you may not get support from your local importer years down the road. Though a problem may never arise, another possible alternative is that you may have to wait around a long time for parts when repairing your turbine or you may have issues communicating with the foreign manufacturer.
Other Considerations
Reliability: How long has this manufacturer been in operation? How long has this model been on the market? Are there many returns or repairs? Does the model perform up to spec?
Safety and protection: Does the turbine have a shutdown mechanism in the event of a severe storm? How about lightning protection?
Grid connection: Find out whether the model can be connected to the grid, if that is a concern to you.
Other Components
Ask the dealer if the following come as part of the package or if you need to buy them separately. Assess each component according to your individual needs:
- Tower: the higher the tower, the stronger wind your turbine can capture. A turbine raised high in the sky is also more likely to avoid turbulence caused by buildings and trees as well as the friction from rough land.
- Batteries: only necessary for storing electricity in off-grid or battery backup systems. If you just want electricity when the wind is blowing, batteries are not a concern.
- Inverter: essential component to convert the variable DC output from a turbine to useable AC.
- Wiring and conduit: transports the electricity from the turbine for conversion.
- Controller / electronics: controls battery charging or input to inverter.
- Meter: provides system management.
