A mini wind turbine sounds like a clever addition to the solar system on the roof. But consumer advocates are dampening expectations: in residential areas, electricity yield often falls far short of what manufacturers promise. We show what yields you can realistically expect, what the limits are and for whom a small wind turbine can still be worthwhile.
Given the high energy prices and increasing climate awareness, more and more people are relying on green electricity and an energy supply that is as independent as possible. Solar energy in particular has experienced a boom at private household level in recent years.
First and foremost are compact balcony power plants that are easy to install and deliver energy quickly. Small wind turbines are also increasingly coming into focus, as wind power is seen as a supplement to solar energy, especially in times when there is little sun.
But the actual benefits of mini wind turbines for your own home are controversial. The consumer advice center has compiled what interested parties should pay attention to before purchasing and provides assistance on topics such as the suitable location, realistic yield expectations, costs and legal framework.
How much electricity does a mini wind turbine really deliver?
While photovoltaics is now considered a relatively mature technology, small wind turbines for domestic use still face practical and economic hurdles in many places. Electricity yields depend heavily on local wind conditions, which are often inadequate in densely built-up residential areas.
In contrast to solar systems, which can reliably supply energy even on small areas such as balconies, the efficiency of mini wind turbines remains limited in many cases. Because their performance depends extremely heavily on wind speed.
Since the output of a wind turbine does not increase linearly, but rather with the cube of the wind speed, there is a strong dependence on the respective location. Even small differences in wind supply can therefore mean the difference between high yields and economic disappointment. For example, if the wind doubles, the yield increases eightfold. However, if the wind halves, only an eighth remains.
An example calculation from the consumer advice center shows how limited the yield of small wind turbines often is. Under optimistic conditions, a system with a rotor diameter of one meter generates around 96 kilowatt hours of electricity per year. If this electricity is used entirely in your own household, this corresponds to a value of around 35 euros.
Although the yield can quadruple if the diameter is doubled, the economic benefit remains mostly manageable, according to the consumer advice center. In practice, the yield is often even lower, depending on the location and system quality.
In comparison, a photovoltaic system with a comparable area would in most cases generate a similar amount or even more electricity. This would also have the advantage that electricity production would take place with greater reliability throughout the year.
Registration, insurance, compensation: What you need to consider
Wind measurement can also be used to make a decision about the suitability of a location. However, in most cases this does not make sense because the costs are usually uneconomical in relation to the expected yield of a system.
Similar to balcony power plants, small wind turbines also have to be registered with the electricity grid operator and the Federal Network Agency. It should also be checked whether the system can be included in building and liability insurance to cover possible damage.
The remuneration for wind power fed in from a small wind turbine is between around eight and twelve cents per kilowatt hour. Similar to balcony power plants, self-consumption also makes more sense with mini wind turbines for the home.
However, those interested have to make compromises when it comes to the service life – especially in comparison to photovoltaic modules. While the lifespan of a PV system is now 20 or more years, this is uncertain and probably significantly lower for wind turbines.
Overall, the consumer advice center’s conclusion suggests that mini wind turbines are rather unsuitable for residential buildings. However, under ideal site conditions, they could be useful in special areas such as on boats or in remote cabins.
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