How big of a wind turbine do you need to power a house?
How do you size a wind turbine for your home?
Discover your solar saving potential
If you intend to use a wind turbine to power a house, most mid-sized homes can work well with a 10kW-20kW system. However, some homes could require up to a 100kW wind turbine. It depends heavily on the energy consumed.
The size of a wind turbine that you use in a home will depend on several factors. One of the most important factors is what you intend to use the wind turbine for.
Some homeowners may buy a wind turbine to power their water pump, or to power their entire house. The wind turbine can vary in size from 20 watts to 100 kilowatts depending on the intended application.
How does a home wind turbine work?
The principle of how wind turbines work is simple; they use the wind to make electricity. The wind is used to turn propeller-like blades, which turn a rotor that spins a generator, which creates electricity. The concept is quite similar to how a dynamo on a bicycle light works.
Wind is a type of solar energy, which is generated via a combination of three events:
-
The sun heating the atmosphere
-
Irregularity of the earth’s surface
-
The earth’s rotation
Due to a combination of these three events, wind flow speeds and patterns vary greatly from one area to another. Various factors like large bodies of water, vegetation, and differences in terrain all affect wind speed and direction.
Wind energy refers to the process via which wind is used to create mechanical power, which can then be converted into electric power. For many centuries, the mechanical power created by the wind was used to grind grain, and pump water. Its latest use is to create electric power.
To turn a wind turbine, the principle of aerodynamic force is applied. The blades act like a plane wing or helicopter blade in reverse. When the wind flows across the blade, it increases the air pressure on one side and lowers it on the other side. Differences in air pressures create drag and lift.
The force of lift is greater than drag, and it causes the rotor to spin. The spinning rotor is connected to a generator, directly or via a shaft, and gears, speed up rotation, allowing for a physically smaller generator. The transition of aerodynamic force into rotary motion is used to generate electricity.
What size wind turbine do I need calculator
The wind energy formula is:
P = 1/2 x ρ x A x v3
Where:
P = power in watts
ρ = air density
A = swept area of blades
V = velocity of the wind
Example of wind turbine power sizing:
What is the power, if the wind speed is 20m/s and the blades are 50 m long?
Solution:
P = 1/2 x ρ x A x v3
v = 20 m/s
Blade length = 50 m
Air density ρ = 1.23 kg/m
A = π × (502)
= 7850 m
P = 1/2 x 1.23 x 7850 x 203
P = 38642 kW
Wind turbine size chart
|
Wind Speed and Expected Power Output (kW) |
|||||||||
|
Wind speed (m/s) |
5 |
10 |
15 |
20 |
25 |
30 |
35 |
40 |
|
|
Power output (kW) |
604 |
4830 |
16302 |
38642 |
75472 |
130415 |
207095 |
309133 |
|
As the table shows, when velocity is doubled, the power increases by a factor of 8. When the velocity triples, the wind energy grows by a factor of 27. The reason for this is that the wind velocity is cubed.
Home wind turbine kits
When it comes to wind power, the consensus is that it is a green source of power. If your area is not suitable for other forms of green energy, you can still go green with a wind turbine. To set up a wind turbine, you will need some land, a high voltage battery bank, and some technical expertise.
You can expect to pay around $1 per watt of wind turbine capacity. As a result, if you buy a 1500W turbine, you can expect to pay around $1500 for it. A typical home needs a wind turbine with a 5 kW capacity to meet its energy needs.
To get to his point, you will need to install a wind turbine with a diameter of around 20 feet. It needs to be placed in an area with strong winds for most of the year. If you have wind speeds of less than 7 mph or winds that are over 90 mph, or if you live in a dense urban area, a wind turbine is not an optimal option.
1.5kw wind turbine characteristics
A 1.5kW wind turbine will not supply all of the energy needs of an average home. However, it is a great starting point when getting into wind turbines. This type of turbine will likely be roof-mounted and can generate enough power to subsidize the power you get from the utility.
It is designed to operate in areas with speeds of 7mph or great, and it can generate around 260kWh of power per month in areas with average wind speeds of 12 mph. its key characteristics are:
-
No scheduled maintenance
-
Simple installation
-
Quiet operation
-
Reliable construction
-
5+ years limited warranty
10kw wind turbine characteristics
A 10kW wind turbine can generate enough energy to power an average home. It has rotor blades of 8-10 meters. Most of these wind turbines come with advanced systems such as remote monitoring and safety systems.
It requires a professional installer and is usually a freestanding system. The system needs wind speeds of around 12 mph to operate efficiently. Some of its key characteristics are:
- Little maintenance
-
Relatively quiet
-
Reliable construction
-
Limited warranty
How to build a wind turbine for home use
Home wind turbine installation is governed by local building codes.
If you plan to install a wind turbine, you will need to consider various aspects. Some of the factors are:
-
Zoning Laws and Height Restrictions
Some zoning laws restrict the turbine height to 500 feet or less. They also need to be at a minimum height of 25 feet to be at their most efficient. In some instances, a wind turbine can be attached to the roof.
-
Wind Speed and Characteristics
An area has to receive enough wind for a wind turbine to be economically viable. However, a wind turbine cannot operate in areas with over 90mph of wind. That means areas that experience regular hurricanes and tornadoes are not right for wind turbines since winds can reach over 100 mph.
-
Turbine Blades
Wind turbines come with different types of blades. Three blades are the standard but wind turbines can have one blade, four blades, or more. The sweet spot is usually two blades.
-
Home Wind Turbine Energy Output
With the use of gears, it is possible to increase the energy output of a wind turbine, even with a small motor. Other factors can be used to augment the output. When buying the wind turbine, you need to check for the output, which is rated in watts. However, most wind turbines cannot operate at their maximum output, and their average efficiency is usually around 40%.
-
Weight
If you plan to mount the turbine on a roof, opt for a lighter model. However, if it is going to be a pole-mounted turbine, weight is not an issue. Modern wind turbines are made of composite materials that lower the weight, giving buyers more flexibility on where to install them.
Wind turbines will often come as a kit that includes everything needed to complete the process. Some kits come with mounting equipment, which includes the pole, while others require that it be purchased separately.
Some kits also come with a controller and provide remote access via any device. Others have been waterproofed, which means they can be installed offshore. Additionally, they will feature anti-corrosion features to ensure they can last a long time.
When building a wind turbine, some key components are needed. These are:
-
Installation tools
-
Blades
-
Motor
-
Central hub
-
Tail
-
Tower
-
Batteries
To begin the process, you will need the necessary tools such as the wire strippers, and soldering irons. You will then need to fix the wind blades to the generator. Once those are fixed in place, you will need to fix them on the pole to capture the wind. It needs to be facing the best wind direction, according to local wind maps of your area.
If you plan to use a wind turbine, you will also need to use a charge controller. It ensures the power getting to the batteries is controlled to prevent overcharging.
When it comes to the battery bank for your wind turbine, it does not need to be as big as for that a solar system. This is because the wind turbine is always running. As a result, there will only be short periods when you do not have wind energy. During those short periods, you can source power from the batteries.
Another important consideration when installing a wind turbine is an electromagnetic brake. This is made possible by shorting the alternator output leads. As a result, it becomes much harder to turn the rotor. It is an important safety consideration when you need to do some limited maintenance to the generator.
Alternatively, if you find it too difficult, you can contact a professional installer to handle everything.
Are domestic wind turbines worth it?
Under the right conditions, a home wind turbine is a practical solution for powering a home. However, it is important to conduct enough research before opting to install a wind turbine. Depending on various factors, including zoning laws, government incentives, and technical factors, other renewable forms of power such as solar energy make more sense.
Hybrid Solar-Wind Systems
An alternative to wind energy systems is a hybrid system. In most of the US, the wind speeds are low in the summer when the sun is brightest and longest. In the winter, wind speeds are high but the sun is at its dimmest with short periods of sunshine.
Due to these unique conditions in large areas of the US, a hybrid system makes a lot of sense. Most hybrid systems are designed for off-grid operation. That means power is sent to the batteries. It ensures that a homeowner can enjoy the full benefits of green energy in summer, and winter.
FAQ relating to home wind turbine sizing
How many wind turbines does it take to power a house?
A single wind turbine with enough capacity between 5kw and 10kw can power a home.
How many years does it take for a wind turbine to pay for itself?
A wind turbine can pay for itself in 5 to 10 years after installation. It depends on various factors such as wind speed and consistency.
How much does a 5kW wind turbine cost?
The average cost of a wind turbine is $1 per watt. A 5kW system can thus cost around $5000 or slightly more because of installation costs and site modifications.
How big is a 50kW wind turbine?
A modern 50kW turbine has rotor blades with an average length of 60 feet. Its pole mount can be 100-140 feet tall.
How big is a 1kw wind turbine?
A 1kW turbine is a relatively small installation. It has rotor blades of around 1 meter long. This type of turbine is relatively light, and can easily be mounted on the roof.
