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ALTERNATIVE ENERGY AT THE
HOMESTEAD
Being a remote wilderness lodge
in Silver Salmon Creek, Alaska,
(Tuxedni Bay area) definitely
has its logistical challenges as
there are no roads to drive to
the lodge. The main access is by
bush plane. Weather is always an
issue, especially in the winter
with the freezing temperatures
and snow conditions. In March of
2009 Mt. Redoubt erupted, which
is 35 miles north of us, gave us
more challenges dealing with the
ash. Producing sufficient power
for our energy needs to keep our
lodge operational is always on
going; something we pay
attention to at all times.
We produce our power with a 3000
watt Whisper Wind generator,
2000 watts of solar, and a 10 KW
Lister diesel generator, 3 KW
Lister diesel and 2 KW Honda gas
generators. If there is enough
wind or sun we don’t need the
diesel or gas generators, which
is what we prefer. We estimate
the wind generator makes between
45-50% of our power, the solar
panels produce 30 to 40% and the
gas and diesel generators
produce 10 to 15% of our power.
The wind generator has been the
biggest producer of power but
also by far the greatest
maintenance burden. It sits on a
110’ tower and we live in a
turbulent windy area, so it gets
lots of abuse. In 2007, the wind
machine was taken off and we
completely reinforced all the
weak areas, put bigger bearings
in, new blades and it’s been
running two years now without
problems. The solar panels are
great as there are no moving
parts on them.
We have three Trace Inventers to
convert 48 volts DC to 120 volt
AC. We recently purchased 4
Solar One 1690 amp hour, 12 volt
battery banks to store the
power, replacing the 16
Surrettes batteries we had for
approximately 10 years. We are
hoping with the new batteries,
we will run the fossil fuel
generators even less. Our goal
is to go “green” in all areas of
our operation. View the
operation first hand when
visiting the Alaska Homestead
Lodge. For additional questions,
please contact us: James &
Shelia Isaak at
james@alaskawildlife.com
or our Technical Advisor, Rick
Zuber with Solar Wind Energy at
(907) 260-3782 or email:
rickzuber@hotmail.com
Wind Turbine (Generator) for
additional information:
The wind turbine is a Whisper
series 3KW originally designed
by Elliot Bayly in Minnesota. It
is a third generation design,
preceded by the Whirlwind series
of turbines, designed in the
1980's which were an upwind two
blade design and governed the
rotor speed with the use of a
yaw drive' fan' connected to a
reducer which walked the machine
around a large turntable gear.
This allowed the machine to find
the wind and also turn out of
the wind at high wind speeds.
The second generation was the
first of the Whisper series but
this machine tilted up to govern
at high wind speeds and used the
weight of the tail to create the
proper tilt up point at the
desired wind speed. This design
had some unusual quirks. For
instance, the machines had a
tendency to spin around in
circles when tilted up in over
speed control mode. It would
also slam down rather abruptly
on occasion when the wind speed
dropped off. The former was not
a real problem, but the abrupt
drop would, on occasion, take
out a blade. Despite these
shortfalls, some of these
machines are still in service
and generating power after 15
years.
Seems Elliot is constantly at
work engineering a new design,
so inevitably a third generation
was born. This design was a
combination of a side tilt and a
vertical tilt up, called an
angle governor. It tilts up and
over at a 45 degree angle thus
avoiding some of the problems of
the previous tilt up design. A
cylindrical coil spring is used
to push the machine back into
the wind when the wind speed
drops below govern speed. Also a
pneumatic cylinder is used to
prevent the abrupt movements of
the yaw system that plagued
earlier models. Like its
predecessors, this 3 KW Whisper
series is also a two blade
design. The blades for this
model are 15 foot in diameter
and their composition has
evolved considerably. Currently
the blades are fiberglass
reinforced with a foam core.
Elliot sold the operations of
World Power Technologies of
Duluth, Minnesota to Southwest
Windpower in 2000. Along with it
came the Whisper line of wind
turbines.
There were design flaws with the
original blades and James took
it upon himself to make them
indestructible by adding a layer
of carbon fiber and a layer of
Kevlar. This increased the
weight considerably but it also
made them much more serviceable.
Due to turbulence in the area
from a mountain a few miles to
the North, the machine would get
kicked around pretty good when a
strong North wind comes through.
The high wind speeds combined
with the turbulence (even at 110
feet) wore the yaw drive
bearings out over the period of
about 18 months.
James completely rebuilt the yaw
drive system with much stouter
bearings of larger diameter and
stacked them to better
distribute the load. This has
been a very successful
modification.
The two blade design is more
efficient than a three blade
design as less turbulence is
created by two blades. The
magnets used are ceramic which
makes good use of the high speed
twin blade design. However, the
high speed of the blades creates
more wear on the bearings and on
the blade surfaces and also
creates greater centrifical
force which adds stress to the
yaw system when the machine
tilts out of the wind.
Most all current wind turbine
manufacturers have adopted the
use of rare earth Neodymium
magnets with a gauss rating far
exceeding the best ceramic
magnets. The increased densities
of magnetic lines of force make
power generation possible at
much slower rotor speeds. This
lends itself better to the use
of a three blade design, which
has more torque at lower RPM's
and better, smoother performance
in the over speed govern mode.
Despite the problems that have
occurred, the Whisper 3KW has
produced a lot of power for
James and Shelia over the years.
Between the 2KW solar array and
the 3KW wind turbine, there have
been periods of several months
where no diesel power was
required.
Rick Zuber
SolarWind Energy
Add link for Solar Power for
additional information:
SOLAR POWER and the MPPT
controller
One of the biggest breakthrough
technologies to occur in
photovoltaics is the Maximum
Power Point Tracking charge
controller, or MPPT charge
controller.
It has allowed us to get more
power out of solar panels over a
greater range of battery states
of charge.
The MPPT controller is basically
a DC to DC converter with a
tracking function that modulates
the input and output levels.
Taking the DC from the panels
and converting it to AC in the
several thousand KHZ range, then
rectifying and filtering that
AC, turning it back to DC at a
more efficient power transfer
point.
The energy coming from the
panels is constantly in flux.
The voltage and current levels
are always changing due to
variations in atmospherics,
shading and solar isolation.
Likewise the battery state of
charge is always in a state of
flux as are loads connected to
the battery.
The job of the MPPT controller
is to find the voltage and
current combination that allows
the most efficient transfer of
power from the solar array to
the battery bank.
The only way for the device to
know where the Maximum Power
Point is, is to sweep through a
range of possible voltage and
current combinations, most with
the aid of microprocessors, and
compare the level of power
transferred at each point along
the curve, as shown in figure 1.
Since power is a product of
voltage times current, maximum
power transfer can be achieved
by making a broad sweep across
the entire usable range of
possible combinations of voltage
and current. This could be
considered a broad sampling of
power transfer levels along a
curve. At one end of the
spectrum the voltage will be
relatively high and current
relatively low. At the opposite
end of the range the voltage
will be relatively low and the
current relatively high. The
controller notes a range of
current and voltage combinations
that produces the highest power
output. At some point in between
the extremes, there will be a
small window of maximum power
transfer.
The controller will make ever
changing minute adjustments
constantly seeking back and
forth in tiny increments to see
where power transfer rates drop
off, and then re-finding the
optimum center point.
Without this micro-sweeping back
and forth to identify power
transfer drop off, the device
would have no way to know where
maximum efficiency, or the ideal
center, is at that particular
time under those particular
conditions.
There are actually several
different ways to arrive at a
MPP so not all controllers use
the same circuit types or
approaches. There are different
algorithms, different sampling
methods, sampling rates, and
different circuit concepts.
 Figure
1
Another added benefit to the
MPPT controller is that for some
applications it allows us to run
higher DC voltages from the
panels to the batteries,
allowing for less voltage drop
in the wiring. This is where the
DC to DCV converter aspect comes
in handy. This is particularly
true for 12 and 24 volt systems
where voltage levels are
relatively low and current
levels are relatively high. With
a long run of cable there is a
very real possibility for
substantial voltage drop and an
unwanted loss of power.
Normally in a 12 volt system,
for instance, an array of 12
volt solar panels would have to
be wired in parallel, increasing
the power by increasing the
current. With high current
levels, power wasted in cables
becomes a very major
consideration and huge wire may
be needed to mitigate this loss.
With an MPPT controller though,
we can series several panels
together, effectively increasing
the voltage, and decreasing the
current running through the
transmission lead, allowing for
the use of smaller wire, longer
runs, and/or reducing loss in
the transmission lead.
This higher voltage is converted
back into current in the output
circuitry of the controller.
For instance let’s say we have a
24 volt battery system and three
175 watt solar panels rated at 5
amps at 35 volts for a total
array power of 525 watts.
5(Amps) X 35(Volts) = 175
(Watts)
3 panels X 175 Watts = 525 total
array Watts.
Wiring these panels in series we
would have approximately,
35(Volts) X 3 = 105 Volts at 5
Amps.
Still a total of 525 watts.
(105(Volts) X 5(Amps) = 525
watts)
At the output of the MPPT
controller where the battery
voltage is 24 volts the current
would be approximately 21.875
Amps instead of the original 5
Amps we started with. But since
the voltage is lower we still
end up with the same power level
(24(Volts) X 21.875(Amps) = 525
Watts.
Of course in the real world
there are some conversion losses
but typically these are
outweighed by the substantial
reduction in transmission lead
losses.
Most MPPT controllers for stand
alone battery systems can handle
DC voltages up to 150 ~ 200 VDC
peak open circuit voltage.
During the winter months
over-voltage can become a
problem, particularly in cold
climates like Alaska as solar
panels are more efficient in
colder temperatures and
consequently produce higher
voltages. Cold temperatures,
aided by reflection off of the
snow and a lack of dust and
pollen in the air, can make
series wiring schemes that were
fine for summer months, produce
dangerously high voltages in
winter. Particularly in the late
winter when days begin to get
longer and the angle to the Sun
becomes less acute.
At least one wind turbine
manufacturer has developed a
highly accurate voltage limiter
that allows their turbine to be
used with an MPPT controller,
limiting the voltage to exactly
149.5 VDC.
Rick Zuber
Solar Wind Energy
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