Author: Pernille Manicus
There is a lot of attention towards mini and micro wind turbines at the moment, and below we have collected some points about this type of wind turbine. Nordic Folkecenter has actually tested mini wind turbines several times.
Mini wind turbines are basically built to charge batteries, and are therefore supplied as a starting point in 12, 24, 36 and 48 volt (DC) versions, depending on how many batteries are connected. Therefore, it requires an inverter, which will convert the battery voltage into 230 volt AC, which is what comes out of your socket.
Mini and micro wind turbines are primarily used in places where there is no access to the public electricity grid, e.g. in the maritime sector and at off-grid holiday homes. In addition, mini and micro wind turbines have not been developed for the many annual operating hours (approx. 6000 hours) unlike a Danish produced household wind turbine.
A test at Nordic Folkecenter
At Nordic Folkecenter we tested a 600 watt mini wind turbine with a rotor diameter of 1.5 meters placed on a 12 meter tower in Thy (very windy region). It produced 400 kWh in one year. This corresponds to 40 liters of oil or 85 kg of wood pellets.
Lifetime of the tested turbine: 2 years. After 2 years, the mill started making more noise. The magnets in the mill rusted and destroyed the mill. That in spite of the fact that the tested 600 watt turbine should be seen as a higher quality product, with a price of DKK 20,000 (approx 3,000 €).
The full investment on turbine + tower (because tower is power) + inverter + foundation (+ batteries) in a private setup will result in close to 50,000 kroner (approx. 7,000 €), and in this case it will be some very expensive kWh, when production is not higher.
If the owner of this mill is not able to carry out repairs and maintenance on the mill himself, the owner must estimate an expense for a service company, which can easily amount to DKK 1,000 (ca. 130 €) per hour, according to Danish rates.
The good advice
If you consider buying a mini or micro wind turbine, we advice you to consider the following:
Even if it is a mini or micro wind turbine, where the rules are more relaxed than for a household wind turbine – you must remember to apply for permission to set up from your municipality before you invest.
Regardless of the size of the wind turbine, the regulations apply on how much noise your wind turbine is allowed to emit, and this is measured by the landline. Since many mini and micro wind turbines do not have an accredited noise measurement, the municipality can at any time demand one to be carried out. Such a noise measurement can easily run up to DKK 30,000 (approx. 5,000 €). Therefore, choose a certified mini or micro wind turbine where an accredited noise measurement has been carried out.
Several previously tested micro and mini wind turbines at the Nordic Folkecenter are made of aluminium, and are put together in a way where they are almost impossible to take apart and repair. In addition, aluminum will rust and oxidize over time.
Of course, all these apply in urban and peri-urban surroundings. If you plan to use the wind turbine out in the wild (e.g. a small house in the fields, with a lot of space around) some of these problems may not apply. However, given the relatively short lifetime, the cost and the maintenance requirements, maybe you may be better off with a PV/battery system.
Remember: when investing in micro and mini wind turbines, make sure you invest with the right manufacturer/retailer. You can possibly see reviews of companies on Trustpilot.