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Frequently Asked Questions - and Answers!
General Customer 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.
What does “quiet” mean?
Because of the vertical axis design, sound levels are about 5 decibels above ambient, rendering it virtually inaudible.
How Much Does a Windspire Cost?
In the US, a complete Windspire wind turbine typically costs between
$9,000 and $12,000, fully installed. After rebates, the costs can be as
low as $3,800.
Are There Tax Credits Available?
The U.S. government provides a 30% tax credit for the total cost of the
unit including installation. Local municipalities also offer rebates as
do local power companies.
Where are the Windspires Made?
Made in the USA. Windspires are manufactured in Manistee, Michigan at Mastech Manufacturing.
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.
What Does the Windspire Come With?
The Windspire comes complete with a high efficiency generator,
integrated inverter, hinged monopole, and wireless performance monitor
for easy installation and seamless operation. The unit can be
dealer-installed in less than four hours after a 2’ x 6’ concrete
foundation has set.
Is the Windspire a Grid-Tie or Off-Grid Product?
The currently available Windspire 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.
What Is the Maintenance?
The Windspire has zero maintenance as ball bearings are greased for
life. Durable construction enables it to produce power for 20+ years. A
dual layer paint coat, rust proof spray, and zinc plating are applied
for weather protection.
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 consumed 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, although in reality it
cuts in a little lower - closer to 3 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.
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 110V 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.
Does the Grid-Tie Windspire need to be connected to its own fuse?
Yes. It requires its own 20 amp fuse.
Can I make 3 Phase power using 3 separate Windspires?
Yes. We are developing a 3-phase optimized Windspire, but in the mean time you can use 3 Windspire to create 3 phase power.
Economics
How Much does the Windspire Cost?
In the US, a complete Windspire wind turbine typically costs
between $9,000 and $12,000, fully installed. After rebates, the costs
can be as low as $3,800, with a limited 5-year warranty. Shipping costs
vary the price.
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 is 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?How is Overheating Prevented?
Yes, the rotor speed is limited by a brake that is applied if
it runs at 410 rpm for more than 30 seconds, or if it reaches 430 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.
How is Overheating Prevented?
A specialized inductor that combines high efficiency with
limited damping helps keep temperatures down. A finned design also
helps to dissipate heat. There is also a temperature monitor inside the
generator housing that triggers the controller to limit rotation speeds
if temperatures do move past the threshold.
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.
Can the Windspire With stand 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. We also
recommend the use of stainless steel fasteners for salty coastal
conditions, although this costs a little more.
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. Unfortunately there are no
performance or rating standards in place yet for small wind. The
American Wind Energy Association (AWEA) is currently leading the
process for developing a set of standards and a certification process
but it is not likely to be implemented until 2010. 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 should buyers beware of?
Exaggerated claims: There are no standards in place yet in the USA for testing small wind turbines and reporting on performance. Unfortunately, this leads some less-than reputable companies to make exaggerated claims about their products, and leads to a buyer beware environment. Ask specifically how a turbine is rated, and how it is tested. If you get vague or inadequate answers, it is probably a red flag.
Ratings associated with extremely high wind speeds: The emerging industry standard is to use 25 mph for the power rating, and average wind speeds of 12 mph for energy ratings. If you see far higher numbers, beware - they lose meaning in the real world.
Lack of real-world, independent testing: Was the turbine actually tested outside in the real world at a fully-equipped test site, or was it put on the back of a truck to produce artificial wind conditions - or worse still, was it "tested" in a wind tunnel (very artificial conditions), or even worse than that - was it not tested at all? A report of small wind turbine manufacturers in 2004 showed that only half of them did any performance testing at all, and only a quarter did independent testing.
Why does the Windspire appear to turn more slowly than a propeller turbine?
The Windspire’s airfoils are at a constant and small radius from the axis, so every part of the airfoils moves at the same speed, about 2 times the speed of the wind. In contrast, the blades of a propeller are rigid, so the area near the hub moves slowly, while the tips move really fast (about 7 times the speed of the wind) around a larger circumference. A good analogy for how a propeller turns is the way a parade line turns a corner - the inside moves very slowly while the outer people almost run. In fact, the hub of the Windspire rotates faster than some propeller-style wind turbines.
Why does the Windspire appear to wobble in low winds?
The appearance of wobble in the rotor is normal. The low end wobble is inherent in a Vertical axis system and clears up at 80-90 RPMS. Some of it appears to be the type of wind it is receiving. When you look at the top of the unit you see the wobble and none at the bottom. That is because the only fixed point on the VAT Shaft is at the bearing on the bottom and that is the way it is designed. It can be compared to a top spinning at low speeds. Once the centripital acceleration is the same from the top to the bottom of the airfoils the wobble goes away.
What happens when the wind changes directions or is turbulent?
When the winds change directions with the Windspire or other VAT's the turbine will still pick up the wind and give more constant energy production. A horizontal axis wind turbine (HAWT) the turbine may stop as the blades or tail seek the wind. A consierable amount of energy will go into starting the turbine up again. This may happen several times a day even though the winds seem good for wind.
Wind Industry
What is the definition of “Small Wind”?
“Small wind” generally refers to wind turbines under 100 kW of
rated power, although definitions vary. “Micro Wind” is generally for
turbines under 10 kW, but often the term small wind is used for this
category. There are no hard boundaries on these definitions.
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