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Copyright
©Denis Lenardic
2001-2010
All Rights Reserved
Friday
12th Mar, 2010
05:12
This page was last time updated on
30th Dec, 2007
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Springerville generating station solar system
"There are only two ways to live your life. One is as though nothing is a miracle.
The other is as though everything is a miracle."
(Albert Einstein)
SGSSS plant in 2003 and 2004
(courtesy: picture 1
Global Solar Inc., picture 2
Tucson Electric Power).
Where are you: Home > World's largest PV plants > SGSSS
The Solar System located at the Springerville Generating Station (SGSSS) was designed to
be built in phases with a fully completed continuous generating capacity of 8,000 AC kW.
The system was designed around installation of 64 building block systems with a nominal
size of 125 AC kW per system. Blocks were configured in two different sizes to accommodate
PV modules of different efficiencies. While the fully completed system will use 88 acres
of ground, the initial leveling was 38 acres, for 24 unit blocks. A second phase of ground
preparation in 2003 developed an additional 20 block locations on 20 acres. Leveling was
performed in a manner to barely disturb the ground to leave as much native vegetation in
place as possible. A water permeable dust/erosion control agent was placed on the soil
after leveling to promote growth of the native grasses. Growth of weeds is being
controlled by manual removal until such time as the native grasses reestablish themselves
as the dominant species. The native grasses generally reach a full growth height of about
8 inches and the lower edge of the PV modules are placed 8 inches above the ground.
The modules are fixed, south facing with a tilt of 34 degrees from the horizontal.
While the area is fenced to keep out cattle, lizards and small mammals have moved back
into the area and use the PV modules for shade.
Text and pictures provided by Tom Hansen, Tucson Electric Power (last update, January 2006).
Other topics:
World's largest PV plants
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Springerville Generating Station Solar System - Fact Sheet
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System Information
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Total Array Coverage Area
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44 acres
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Number of PV Arrays - Fixed at 34 Degrees Tilt
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34 arrays
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Fixed Array Azimuth Direction
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180 Degrees - South
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Total Number of PV Modules
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34,980 modules
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Total PV DC Array Capacity Rating (STC)
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4,590 kW
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Total Inverter AC Capacity Rating
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5,100 kW
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Total System AC PVUSA Rating
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3,812 kW
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System Actual AC Output - 1 Minute Rating
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5,113 kW (Dec 6th) *
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System Actual AC Output - 15 Minute Rating
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4,644 kW *
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Actual 2005 Annual Net AC Energy Production
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7,532.42 MWh
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Expected 2006 Annual Net AC Energy Production
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7,650 MWh
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Average Annual Energy Production Site Rating
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1,730 kWh / kW DC
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Reliability 2003/2004/2005
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99.78% / 99.72% / 99.81%
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Inverter Information
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Inverter Type
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Xantrex PV-150
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Rated Capacity
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157 kVA
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Operating Power Factor
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0.99
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Total Harmonic Distortion
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Less than 3.0%
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Inverter Efficiency - Average Daily Cycle
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96%
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Inverter Reliability 2003/2004/2005
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99.917% / 99.87% / 99.92%
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Array Information
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Parameter
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ASE
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First Solar
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BP Solarex
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Number of Arrays
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26
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4
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4
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Module Type
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300 DG/50
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FS-45 & FS-50
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MST-43
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Modules per Array
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450
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2688 to 3024
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3000
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Modules per String
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9
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5
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Strings per Row
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2
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16 to 18
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20
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Power per String STC
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2700 W
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300 W
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215 W
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Design String VOC
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595 V
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580 V
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545 V
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String Operating DC Volts
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380 - 430 V
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300 - 360 V
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300 - 310 V
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Design Array Power STC
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135 kW
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134,4 kW
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129 kW
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Module Failure Rate 2004
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0.009 %
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Pre-Commercial
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0.092 %
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All SGSSS Oil Filled Transformers use oil derived from seeds, EnviroTemp fluid, which is
readily biodegradable and is non-bioaccumulating. Because it is a seed-oil based fluid it
can be differentiated from mineral oil regulation. And, the transformers achieve 99.2%
energy conversion efficiency.
* = Cloud Enhanced Power Output.
Springerville generating station solar system - SGSSS.
(picture source:
Tom Hansen, Tucson Electric Power)
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Detailed description
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PV array blocks located on the east side of the field are built on a footprint of 300 feet
north to south by 140 feet east to west, and will accommodate PV modules with efficiency of
10% or more. Today, twenty-six (26) of these blocks have been completed, all of them using
crystal silicon PV modules of type 300 DG/50 from RWE Schott. Each unit uses 450 of the
modules for an STC DC power rating of 135 kW.
Blocks located on the west side of the field are built on a footprint of 300 feet north to
south and 250 feet east to west, and will accommodate PV modules with efficiency of 5.5% or
more. Four (4) of these blocks have been completed each with 2,688+ Cad-Tel First Solar
FS-50 PV modules for an STC DC rating of 134.4+ kW. Four (4) others units are completed
each with 3000 a-Si BP Solarex MST-43 PV modules. These units have an STC DC rating of
129 kW.
All units use a Xantrex PV-150 inverter to convert the variable 300 to 600 volt DC power
to 208 volt 3 phase AC power. The inverters have a maximum rating of 157 kVA, at which
point they will limit output or come off line, followed by an automatic restart. Each unit
has a DC disconnect, 208 to 480 volt step-up/isolation high efficiency transformer, revenue
meter and AC disconnect. Because of the high conversion efficiency and fast response time
of the inverters, in April 2005 the maximum inverter power level allowed was limited in
software to 92% of rated capacity to prevent overloading the system AC grid components
during cloud enhanced solar insolation conditions.
Groups of four (4) units are connected in parallel to each of eleven 500 kVA 480 volt to
34,500 volt high efficiency step up transformers. Each transformer has a continuous
rating of 500 kVA and can accommodate up to 650 kVA for brief intervals. The high voltage
sides of the transformers are connected in parallel in a daisy chain configuration to a
34.5 kV underground distribution line which connects to the overhead 34.5 kV distribution
line which feeds the well field pumps of the Springerville Generating Station.
The pumps operate continuously with an average load of about 10,000 kW.
The SGS Solar System is a customer based distributed generation system providing power
to the pumps. As the distribution line is connected to the main switchyard at SGS,
any excess energy produced will flow through the switchyard to the grid.
The system produces the most power capacity during the cooler months of the year when the
sun is near latitude angle. This typically occurs in March and April. Solar insolation at
the 6650 foot elevation site has been measured at over 1,500 watts per sq-meter in these
months for short periods and at over 1,300 for one minute averages. These events occur
during cloud passage which creates strong sunsplash conditions. The actual AC output of
the units during severe sunsplash have been measured at 157 kW for 10 second averages.
Consequently, the short term power output rating of the system with 34 units installed
is an actual 5,113 kW measured for a one minute average on December 6th, 2004. The revenue
meters measure 15 minute power output. Actual measured 15 minute average unit AC energy
outputs in 2004 total 4,644 kW for the full system. Thus we are rating the total 15 minute
AC system output at 4,644 AC kW. However, while these system output conditions must be
taken into account during system design, they are not an indication of long term energy
output.
The annual net AC energy production in 2005 was 7,532,420 kWh. Based on experience with
the installations to date, we expect the annual net AC energy production from the 34 units
to be just over 7,650,000 kWh in 2006. Energy production reliability of the inverters was
99.92% and reliability of the entire PV system was 99.81% in 2005.
Continued expansion plans are currently on hold while module prices awaiting a reduction
in module prices to below pre 2004 levels. Future plans are to install 125 AC kW units on
ten (10) prepared pads in 2007 and to prepare land and power distribution infrastructure
in 2007 for the final 20 units. The type of PV modules to be installed in that final
phase will be in large part determined by actual energy production of existing systems as
well as installed cost data bid for PV equipment.
The system operates as an unmanned site and is monitored continuously via an Internet
based communications channel. Nearly all operational functions can be performed by remote
control, including inverter reconfiguration. Alarms are logged. Data is taken from each
of the 34 inverters and the revenue meters on 10 second scan cycles and averaged for one
minute archiving. Performance information is developed from the raw data and reviewed in
Excel spreadsheet and graphical chart form daily. Spare parts are maintained on site and
local based service personnel dispatched to site to perform repairs in response to alarms.
Near real time performance is available on the Internet at GreenWatts pages.
If the need exists, there is sufficient room to place another 8,000 kW block south of the
systems currently being installed. The distribution line is capable of supporting 36 MW of
distributed generation.
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SGSSS On-line
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Springerville Solar Array Output -
electricity production and other interesting data available on-line.
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