Frequently Asked Questions - and Answers!

General Windspire Questions

What Size is the Windspire?
It is 30 feet tall and four feet wide, designed to come in under the typical 35 ft height restrictions of local municipalities. Base pole extension kits of 5, 10, and 20 feet are also available to raise it higher.

How much “swept area” does the Windspire have?
The Windspire has 80 sq/ft of swept area.

How heavy is a Windspire?
A Windspire is about 650lbs.

What does “quiet” mean?
Because of the vertical axis design, sound levels are about 5 decibels above ambient, rendering it virtually inaudible.

Where are the Windspires Made?
Made in the USA. Windspires are manufactured in Manistee, Michigan at MasTech Manufacturing.

What is the Windspire made of?
The Windspire is made 85% of steel (main structure). The remaining 15% is extruded aircraft grade aluminum (airfoils) and a small percentage of electrical parts in the inverter and generator.

Aside from being a “Green” appliance, is the Windspire made of recycled materials?
Yes. The Windspire® is made of 69% recycled materials. This can be broken down as follows: Steel (85% of product) is 69% recycled; Aluminum (10% of product) is 90% recycled; Electronic components (5% of product) are 35% recycled.

How Does the Windspire Work?
The Windspire wind turbine operates with three sets of tall, narrow airfoils that catch the wind while spinning around a vertical axis. As the rotor turns, a generator conditions the energy into electricity. The inverter then converts the electricity to an alternating current(AC) that can be used for buildings and homes.

Is the Windspire a Grid-Tie or Off-Grid Product?
The Windspire that is currently available is grid-tie, which requires that the Windspire be tied into the local utility’s grid. For safety reasons, the Windspire will not work if a connection cannot be made to the grid. Mariah Power has future plans for an off-grid version of the Windspire.

Are the fasteners for the Windspire metric or standard sizing?
The Windspire fasteners are all metric sizing.

Power And Energy

How Much Energy Will the Windspire Produce?
The 1.2kW Windspire will produce approximately 2000 kilowatt hours per year in 12 mile per hour average winds. This is approximately 1/3 to 1/5 of most homes in the US, about ½ the average European home, and several homes in developing countries.

What is the difference between Energy and Power?
At wind speeds greater than 8 mph, the Windspire will begin producing power, which is measured in Watts (W) or kilowatts (kW). Power output jumps up and down as quickly as the wind changes speed, so the industry measures output over time in kilowatt-hours (kWh) which is how many watts of power are produced over a full hour. Your electric company charges you for energy usage based on the rate/kWh. Over the course of a year, the 1.2kW Windspire will produce approximately 2000 kWh in 12 mph average winds to help offset the energy you require from your electric company. This is approximately a quarter of the energy usage of an average home.

What’s the difference between a kW (kilowatt) and a kWh (kilowatt-hour)?
A kilowatt is an instantaneous measure of power. At any moment, the power that is produced by a small wind turbine is measured in watts or kilowatts (1000 watts). A kilowatt-hour is a measure of energy production: how much energy is produced over one hour. For example, if you turn on a 60W (.06 kW) light bulb for one hour, you draw .06 kWh. If you keep it on for a full year, you will use .06 kW x 8766 hours = 526 kWh. Of course, you should never do this!

Where Do Power Curves Come From?
True power curves come from lots of data taken at a real-world test facility. Data is matched with wind speeds taken from anemometers (wind measuring devices) placed at the hub height (center of rotor), and then “binned” to get lots of data for each wind speed. From the many data points, a line of best fit becomes the power curve. The standard for power curves is to use sea-level air density, so sometimes power curves are then corrected for air density differences. There are also power curves derived from calculations, wind tunnel tests, back of vehicle tests – however because these don’t provide the true variability in wind speeds and quality, the results are often very unrealistic when compared with of real world installations.

What affects power output?
Power output is related to rotor size, air density, wind speed, and the efficiency of the wind turbine. The Windspire wind turbine has a comparable efficiency to most small propeller turbines.

At What Wind Speed does the Windspire Begin Producing Electricity?
We publish a cut-in speed of 4 m/s. However, the speed of cut-in is virtually irrelevant, because the amount of power produced at the bottom of the power curve is negligible. What is more important is how plump the power curve is, and the scale it reaches at higher wind speeds. This will contribute far more to the energy produced by a wind turbine.

What is the Peak Power Production of the Windspire? 
Peak power is around 1.6 kW at a wind speed of 30 mph wind. 

What Happens if my Windspire Produces More Power than I Use? For grid-tie units, your meter will literally spin backwards. For off-grid applications, the excess power will be dumped into heat. With the Smart Inverter incorporated into the Windspire, the firmware allows the rotor to slow down so as not to produce excess (waste) heat.7.

Why do you measure average energy output instead of daily or instantaneous?
Wind energy differs from solar because wind is much more variable than solar energy. If you think about it, when there is sun light, it is very consistent. The sun comes out at a set time of day and goes down at a set time. Wind fluctuates daily and seasonally so finding a daily output level is very difficult. Averages will help you evaluate your energy bill and give you a starting point when comparing different renewable energy systems.

Electricity and Electronics

How does the Windspire turn wind energy into electric power I can use in a home or building?
As the wind pushes the rotor around, the rotor turns a generator. The generator is basically a set of magnets that spin close to copper coils. The moving magnetic field from the magnets induces an electric current in the copper wire. This current then needs to be conditioned into an AC current by an inverter so that it is compatible with standard grid electricity. The generator and inverter are housed in the disc just below the rotor. The electricity then flows down a wire through the pole, and under the ground to connect with your home or building.

Is the Windspire a Grid-Tie or Off-Grid Product?
The currently available Windspire is grid-tie, which requires the unit to be tied to the local utility grid. In effect, the grid serves as the best, lowest cost battery there is. An off-grid version of the Windspire is in development and will be available soon.

Can I Sell Electricity Back to the Grid?
Many utilities offer net metering agreements that allow customers to receive credit for, or sell excess power back to the grid.

What is an Inverter?
An inverter is an electronic component that conditions the electricity for a specified type of output. For example, it needs to be consistent with 120V grid electricity in order to make it useful for grid-tie in North America. Our inverter consists of an electronic controller, and firmware - a computer program that is the brains behind the controller. The Firmware allows the inverter to be a lot smarter and adjust to changes in rotor speed and temperature, for example, than a simple electronic controller.

What if I want to use my own inverter for the Windspire? Can I do this?
No. The Windspire has been specially designed to operate the spinning speed, control energy output and integrates with the generator of the Windspire.

Does the Grid-Tie Windspire need to be connected to its own fuse?
Yes. It requires its own 20 amp fuse.

Can I link multiple Windspires together with the same electrical connection?
No. Due to National codes, each Windspire® must have its own grid connection.

How do I know if my Windspire is producing any electricity?
Mariah Power has developed their own software to wirelessly monitor the output of the Windspire. This software package is an additional package that can be purchased through your local dealer.

Economics

How Much does the Windspire Cost?
The Windspire is the most affordable renewable energy appliance in the 1 kilowatt range. The Windspire comes as a complete system that includes poles, rotor, generator, inverter, and wireless performance monitor, so there are no expensive extras to purchase. A 30% federal tax credit (available in the USA) and local rebates are available in some areas. The average payback is under 10 years.

Are There Tax Credits Available?
The Federal Government provides a 30 percent tax credit for the total cost of the unit, including installation. Many state and local municipalities also offer rebates, as do local power companies.

To what extent will a Windspire power my home?
This is difficult to answer, because electricity use varies widely by home size, age, construction, climate, and the occupant’s habits. Furthermore, the power you can expect depends entirely on your wind regime. The best place to start is with your electricity bill and a wind map of your area. In a true generalization, a Windspire can power about 1/3 to 1/5 of the average US home, about ½ the average European home, and several homes in developing countries.

Safety and Environment

Is it Safe for Birds and Bats?
The Windspire airfoils move at a lower speed than most wind turbines and are more visible to flying birds. So far, we have had no reports of collisions - and we have had one report of a nest built under an active unit. You should also be aware that collisions with small wind turbines in general are very rare – overall they account for less than 0.003% of human-caused bird death - although the media has tended to hype them. To put it in perspective, cats, windows, and automobiles kill over a billion birds a year in the USA.

Is There a Brake for High Winds?
Yes, the rotor speed is limited by a brake that is applied if it runs at 405 rpm for more than 30 seconds, or immediately if it exceeds 420 rpm at any instant. Once applied, the brake will stay in effect for five minutes. The purpose of the brake is to preserve the structural integrity of the Windspire in extremely high stress situations. The brake does not bring the unit to a complete stop, but it brings it down to a slow rotation. If you are expecting a wind storm of prevailing winds over 105 mph, you should lower your Windspire to the ground for the storm.

Why is a dynamic brake applied to the generator? Wouldn’t you want the Windspire to spin as fast as possible?
A dynamic brake is applied to the generator in high winds to reduce stress and maintain the structural integrity of the equipment so that you can enjoy a 20 year plus life span on the unit. Be wary of any wind generators that are sold without a braking system in place.

How is Overheating Prevented? 
Internally there is a fan that cools the electronics. The inverter constantly monitors the temperature inside at 3 locations and if any of the sensors exceed safe operating limits the inverter will take action. If the wind in low to moderate, then the inverter will reduce the power output by applying the brake in an attempt to reduce the temperature. At high winds (RPM) or if it can't cool enough then it will shutdown for ½ hour to cool before restarting.  

Siting

Are There Specific Requirements for Potential Customers?
A Windspire site requires land with unobstructed wind and adequate space for installation. The Windspire also needs at least class two winds - ideally class three (an average of 12 mph). You should also select the Windspire model that is appropriate for your electricity needs (grid-tie, vs off-grid, voltage in your country, etc.)

How much wind do I need for Windspire to make sense?
In general, an average of 12 mph (5.5 m/s) or more, although in some circumstances it may make sense in lower wind regimes. Doubling the wind speed gives you eight times as much power from the wind. Wind turbines get most of their power from the time of day when the wind is really blowing.

What if I want to reach higher wind speeds above 30 feet? Do you have extensions that I can purchase for my Windspire?
Yes. We offer extension poles in 5’, 10’ and 20’ kits. Ask your local dealer about pricing and installation information.

How far apart do I need to place my Windspires from each other?
Depending on the direction of the prevailing wind, we have a chart for suggested minimum spacing.  

Do I need a crane to install a Windspire?
No, a certified Windspire dealer will install your wind turbines.  The Windspire is assembled horizontally on the ground and then raised via a hinge at the base plate of the unit. This makes raising and lowering the unit a simple task.

Can the Windspire Withstand Salt Air?
Coastal conditions are challenging. We currently take three measures to protect the steel structure from salt air: First, we etch the steel with phosphorous, second, we coat it in a zinc primer to protect the base metal, and third, we apply a top coat of industrial grade paint, the same kind as is used on steel bridges. If you are still worried about rust, we have a Marine Package available that replaces all fasteners with stainless steel and an enhanced rust proof coating. Ask your local dealer about the Marine Package

How big of a foundation does a Windspire require?
For a typical installation, the Windspire requires a 6ft deep x 2ft wide hole to be dug and filled with 1 ½ yards of concrete. Special soil conditions may have different requirements. Your Windspire dealer will take care of pouring the foundation.

Testing and Certification

Are There Standards for Testing and Performance Ratings?
Basic electric standards such as UL and IEEE ratings are required for small wind turbines. The American Wind Energy Association (AWEA) recently created a set of standards and a certification process for small wind turbines. In the next 12-18 months the Windspire will be tested to these standards. Until the new standards are adopted, we recommend focusing your search on independently tested wind turbines with UL certified inverters.

Is the Windspire Independently Tested and Certified?
The Windspire is independently tested at Windward Engineering in Spanish Fork, Utah. This testing allows customers to know what level of power production to expect from specific wind ranges. The Windspire received ETL certification in March of 2008 and has kept this certification up-to-date as we further improve electronic components. The ETL certification includes UL and IEEE testing for the US and Canada. The Windspire is also listed on the CEC's approved wind turbine list, a requirement for many rebates.

Comparing Wind Turbines from Different Manufacturers

What is “swept area” and why is it important when talking about wind turbines?
Swept area is a measurement used to evaluate how many square feet of wind a wind turbines’ rotors can catch. The traditional equation for finding swept area of a HAWT (horizontal axis wind turbine - or propeller style) is by using the equation for the area of the circle [Pi x (r squared)], since propellers create a flat plane. Since a vertical axis turbine has a different configuration, the equation is dxh, where d is the diameter and h is the height of the airfoils. Since the Windspire® has a diameter of 4ft and the airfoil height is 20ft, our total swept area is 80 sq/ft.

Our patented generator creates energy with torque from the spinning rotors. The more torque our Windspire® can produce, the more electricity it will generate. The smaller the swept area, the less torque a wind turbine generator will be able to produce. This equates into less electricity generation. Pay special attention to wind turbine companies claiming large output with low swept area. The physics of some of these designs just don’t add up.