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At a Glance
Rated Capacity: 1.8
KW Rotor: 12 feet / 3.72 meters; 50–325
RPM Alternator: Gearless, permanent magnet
brushless Voltage Output: 240 VAC
(Optional 277 VAC) Estimated Energy
Production: 400 KWh per month at 12 MPH (5.4
m/s) Weight: 154
pounds Tower: Towers from 35-110 feet are
available; height is dependent by
site Technical Specifications: Skystream 3.7 Spec
Sheet (PDF) Warranty: Five year
limited Availability: October
2006 Skystream is initially available primarily for
North American grid configuration (220V/60HZ). Additional
international configurations (50HZ) will be available in late
2006, along with marine and battery charging versions.
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Behold the Winds of
Change
The Skystream 3.7™ is a new
generation residential wind generator that hooks up to your your
home to reduce or eliminate your monthly electrical bill. It’s the
first all-inclusive wind generator (with controls and inverter built
in) designed to provide quiet, clean electricity in very low winds.
This makes Skystream ideal for residential homes and small
businesses.
A residential wind generator from Southwest Windpower,the Skystream 3.7, is
a fully integrated wind generator designed specifically for the
grid-connected residential market. The turbine incorporates a
combination of new technologies, developed in collaboration with the
U.S. Department of Energy’s National Renewable Energy Laboratory
(NREL). According to Michael Elliot, Director of Sales for Latin
America and Africa at Southwest Windpower, the unit has a peak
working-coefficient-of-power (Cp) rating of approximately 0.4 (40%),
while the theoretical maximum of an ideal wind turbine would be 0.59
(59%). The Cp rating is the energy-harvesting efficiency of a wind
turbine.
With no batteries, the Skystream 3.7 connects directly to the
home’s electrical system to supply power. When the wind is not
blowing, the home is powered by the electric utility. Depending on
the local utility, excess electricity generated by the turbine can
be sold back to the utility or used at a later date.
The design uses a 3-phase slotless permanent-magnet (PM)
brushless alternator. The ac power from the alternator is rectified
and fed to a UL 1741-compliant inverter. Paul Thomas, Electrical
Design Engineer at Southwest, stated the resulting dc input voltage
can range from 60 Vdc to 360 Vdc, and the inverter’s split-phase
output is 240 Vac at 60 Hz for U.S. grid-tie compatibility. However,
the inverter is capable of providing an output voltage from 120 Vac
to 250 Vac at 50 Hz to 60 Hz.
The inverter was independently designed for Southwest by Ed Hall.
It is housed within the nacelle of the turbine. Elliot stated that
this is the first inverter optimized for widely varying inputs,
which are characteristic of the energy profile of wind energy. This
is accomplished through a fast-responding control algorithm, making
it different from solar inverters, which receive power that changes
on a much slower time scale.
The SkyStream 3.7 integrates a specially
designed inverter within the nacelle of the turbine.
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The Skystream consumes 5 W, supplied by the home’s electrical
system, to power the control electronics. As part of UL 1741, the
inverter is required to fail open in the absence of power on the
grid.
The turbine is equipped with a 2-way wireless control link that
provides data for gridline voltage, RPM, and output power. The
latter function can be monitored by a PC to maintain a running total
of energy production. Within the next six months, Southwest will
deploy the capability for these turbines to provide data logging of
system parameters directly to the internet, eliminating the need for
a standby computer.
“This new technology is an important step forward for small
wind,” said Robert Thresher, director of NREL’s National Wind
Technology Center (www.nrel.gov/wind). “As
technology becomes more efficient at harnessing energy at low wind
speeds, small-scale users will become more and more able to take
advantage of wind power.”
See if Skystream is right for your
site.
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