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Domestic wind turbines: beware of overly enticing production promises

Infographic on the promises of domestic wind turbine power and actual production in kWh

Today, on many generalist marketplaces — Amazon, ManoMano, AliExpress, eBay, or others — domestic wind turbines are listed at 3000W, 4000W, 5000W, 6000W, 7000W, 8000W, 9000W, 10000W, or even 20000W.

Some advertisements also highlight productions such as: “up to 10,000 kWh per year”.

On paper, these figures may impress. But before buying a domestic wind turbine, one essential thing must be understood: the power announced in watts is not the actual production you will get at home.

A wind turbine does not produce its nominal power continuously. Its production depends on the actual wind, installation height, turbulence, obstacles, the diameter or swept area of the rotor, the type of generator, the regulator, the inverter, any batteries, and the wiring.

Watts and kWh: two concepts not to be confused

A wind turbine rated at 1000W, 3000W, or 10000W displays a maximum or nominal power, generally reached under specific wind conditions.

The kWh, on the other hand, corresponds to the energy actually produced over time.

Simple example:
a 1000W wind turbine that actually produces 1000W for 1 hour would produce 1 kWh. But in reality, it does not stay at 1000W all day. It can produce little, a lot, or nothing at all depending on the wind.

That's why an announcement that only indicates power in watts, without a power curve, without nominal wind speed, and without test conditions, is not enough to estimate annual production.

“Up to 10,000 kWh/year”: what does this figure represent?

10,000 kWh per year is approximately:

  • 27.4 kWh per day
  • 1.14 kW of average power 24/7, 365 days a year

To reach 10,000 kWh/year, it would be necessary to produce on average about 1,140 W continuously throughout the year.

  • Wind turbine rated at 3,000 W: it would need to produce 1,140 W on average, which is about 38% of the nominal power.
  • Wind turbine rated at 5,000 W: it would need to produce 1,140 W on average, which is about 23% of the nominal power.
  • Wind turbine rated at 10,000 W: it would need to produce 1,140 W on average, which is about 11% of the nominal power.
  • Wind turbine rated at 20,000 W: it would need to produce 1,140 W on average, which is about 6% of the nominal power.

This calculation does not prove that an announcement is false. It simply shows that an annual figure must always be justified by specific conditions: average wind speed, mast height, power curve, rotor diameter or area, system efficiency, and electrical losses.

Without this information, the promise remains difficult to verify.

Infographic explaining the difference between power in watts and annual production in kWh of a domestic wind turbine

The swept area: the detail many announcements forget

A wind turbine does not generate energy “by magic.” It captures a portion of the energy contained in the wind.

Production depends notably on:

  • the wind speed;
  • the area swept by the blades;
  • the aerodynamic efficiency;
  • the mechanical and electrical losses;
  • the regulation and the inverter.

The smaller the rotor, the less wind it intercepts. A compact vertical wind turbine, even if displayed with high power, should be viewed with caution if its actual area is small.

For horizontal wind turbines, rotor diameter is often discussed. For vertical wind turbines, the area swept by the useful height and diameter of the rotor is considered. In both cases, the smaller the area, the more significant wind is needed to achieve high production.

Vertical wind turbine: useful, but not miraculous

Vertical wind turbines have real advantages: more discreet design, possible operation with changing winds, sometimes simpler integration, often softer sound perception depending on the models.

But they are not automatically more productive. At comparable announced power, a vertical wind turbine often produces less than a well-placed horizontal wind turbine on a clear mast.

This does not mean that a vertical wind turbine is a bad choice. It means it should be chosen for the right use: design, discretion, energy supplement, battery charging, specific site... and not solely on a very high kWh/year promise.

Infographic on the importance of average wind, power curve, and measurement conditions of a wind turbine

Why marketplaces require particular vigilance

Large marketplaces bring together many third-party sellers. The issue is not the platform's name, but the quality of the information displayed in certain listings.

Before buying a domestic wind turbine, always check:

  1. The power curve: how much does the wind turbine produce at 5 m/s, 8 m/s, 10 m/s, etc.?
  2. The nominal wind speed: at what speed does it reach its announced power?
  3. The starting speed: from what wind does it actually start producing?
  4. The diameter or swept area: is the rotor size consistent with the announced power?
  5. The working voltage: 12V, 24V, or 48V?
  6. The type of output: three-phase AC, rectified current, battery charging, grid injection?
  7. The supplied regulator: is it well-suited for wind power?
  8. The inverter: is it compatible with wind power, and not only solar?
  9. The protections: braking, load shedding, dump load, grounding, disconnection.
  10. The warranty conditions: duration, covered parts, identifiable seller.

A serious product sheet should allow understanding how the wind turbine is used: battery charging, 230V self-consumption, isolated site, solar complement, etc.

Beware of simplified connections

A wind turbine is not connected like a solar panel.

It produces variable voltage and current depending on the wind. Many wind generators output in three-phase AC, with 3 wires, without +/- polarity. A regulator, rectifier, inverter, or suitable charging system is then needed.

A wind turbine should not be directly connected to:

  • a solar MPPT not designed for wind power;
  • a battery without a suitable regulator;
  • an energy station via a solar MC4 input;
  • an inverter not designed for a wind generator.

A reliable wind setup must include regulation, braking or shedding of excess energy, as well as suitable electrical protections.

Infographic for choosing a domestic wind turbine according to use, voltage, connection, and available wind

The actual wind is more important than the rated power

The best way to avoid mistakes is to measure or correctly estimate the wind at your site.

A wind turbine placed too low, behind a house, near trees, on a gable exposed to turbulence, or in a low-wind area will produce little, even if the sheet claims several kilowatts.

Conversely, a more reasonably powered wind turbine, installed in an open area on a suitable mast, can yield better results than a very powerful machine poorly placed.

Before a major purchase, it is advisable to check:

  • exposure to wind;
  • the presence of obstacles;
  • the possible height of the mast;
  • the prevailing winds;
  • local urban planning rules;
  • the interest of a solar complement.

You can use our simulator for a first estimate:
https://www.comptoireolien.fr/simulateur-eolien-production-rentabilite.html

For a wind + solar project:
https://www.comptoireolien.fr/simulateur-hybride-eolien-solaire.html

Regulation: do not forget the location

The installation of a domestic wind turbine must also consider local rules.

In general, under 12 meters of total height, there is no building permit required, but you must check the PLU, the subdivision regulations, protected areas, neighborhood constraints, and any local rules at the town hall.

To learn more:
https://www.comptoireolien.fr/demarches-administratives-pour-linstallation-dune-eolienne.html

Infographic on the regulations and installation of a domestic wind turbine before purchase

Our advice before buying

Do not choose a wind turbine just because it displays “5000W”, “10000W” or “up to 10,000 kWh/year”.

Choose it based on:

  • your actual usage;
  • the voltage of your installation;
  • your average wind;
  • the type of connection;
  • the available height;
  • the seriousness of the technical sheet;
  • the consistency between the rotor size and the stated power.

At Le Comptoir Éolien, we prefer to clearly state the limits: a domestic wind turbine can be an excellent solution to complement a solar installation or for an isolated site, but it must be chosen methodically.

In a future article, we will share production results observed on certain professional range models. This will allow for a more concrete comparison of the stated powers, actual wind conditions, and obtained productions.

To remember: a well-chosen domestic wind turbine can produce usefully. A promise too good, without a power curve or measurement conditions, must always be verified before purchase.

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Frequently Asked Questions

Does a wind turbine produce as soon as it turns?
Not necessarily. A wind turbine can turn with little wind but produce very little useful electricity. Production mainly depends on the actual wind speed, mast height, turbulence, obstacles, wiring, regulator, inverter, and any batteries.
Does a wind turbine continuously produce its rated power?
No. A wind turbine rated at 1000W, 3000W, or 10000W does not produce this power continuously. The indicated power generally corresponds to a maximum or rated power reached under specific wind conditions. Actual production varies greatly depending on the site and installation conditions.
What does a wind turbine announcement of up to 10,000 kWh per year mean?
An announced production of up to 10,000 kWh per year should always be verified with caution. This figure depends on the average wind, the swept area by the rotor, the height of the mast, the power curve, the system efficiency, and electrical losses. Without this information, it is difficult to assess the actual production.
What is the right wind speed for a domestic wind turbine?
An average wind speed around 18 to 25 km/h starts to be interesting for a small or medium wind turbine. Above 25 km/h, a more powerful wind turbine can be considered if the terrain is clear, the mast is suitable, and the installation is properly sized.
Should the wind be measured before buying a wind turbine?
Yes, it is strongly recommended. An anemometer allows you to measure the actual wind speed on the site, check if the wind is consistent, and avoid choosing a wind turbine that is too powerful, too weak, or poorly suited.
Can a wind turbine be installed on a roof or gable?
It is sometimes possible, but often discouraged. Roofs, walls, and gables create turbulence, can transmit vibrations, and impose significant mechanical stresses on the fixings. An independent mast in a clear area is generally preferable, subject to terrain constraints and local regulations.
Is a vertical wind turbine always more efficient than a horizontal wind turbine?
No. A vertical wind turbine can be interesting for its design, discretion, or certain sites with changing winds, but it is not automatically more productive. At comparable rated power, a well-placed horizontal wind turbine in a clear area is often more efficient.
Can a wind turbine complement solar panels?
Yes, wind power can complement solar, especially when the wind blows at night, in winter, or in cloudy weather. However, a regulator or inverter suitable for wind power must be used, and the system voltage must be respected: 12V, 24V, or 48V.
Can a wind turbine be directly connected to an MPPT solar regulator?
No, it is generally not recommended. A wind turbine produces variable voltage and current depending on the wind and requires a suitable wind regulator, with braking or load management. A standard MPPT solar regulator is not designed to directly manage a wind generator.
What should be checked before buying a domestic wind turbine?
Before purchasing, you should check the power curve, rated wind speed, start-up speed, diameter or swept area, working voltage, type of regulator, compatible inverter, electrical protections, and installation conditions.

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