POWER December 2012 - 28

TOP PLANTS
Alamosa Solar Project,
San Luis Valley, Colorado
Owner/operator: Cogentrix of Alamosa LLC
As the largest solar plant of its type in the world, the 30-MW Alamosa Solar
Project is currently enjoying its place in the sun. The innovative project consists
of 504 concentrating photovoltaic (CPV) solar trackers, each featuring a CPV solar
cell panel assembly mounted on a support column. The modular design of
the assembly allows the project to easily accommodate future improvements
in cell technology.
By Angela Neville, JD
Courtesy: Daniel O'Connor Photography
T
he Alamosa Solar Project's site on 225
acres in southern Colorado's San Luis
Valley was chosen specifically for its
outstanding sunlight characteristics, which
are necessary for concentrating photovoltaic
(CPV) technologies. Among the positive attributes
of the location are its high elevation
(7,800 feet above sea level)-which means
there is less atmosphere for the rays to pass
through and, hence, greater insolation-and
the presence of an existing 115-kV transmission
line for interconnection.
The Alamosa Solar Project consists of 504
dual-axis, pedestal-mounted trackers supporting
modules that produce approximately
60 kW each, providing enough power for
about 6,500 Colorado homes. The facility,
commissioned in May, provides electricity to
customers of Xcel Energy's subsidiary, Public
Service Company of Colorado.
The project is projected to generate approximately
76,000 MWh per year, which
displaces approximately 249 million cubic
feet of natural gas that would have been used
by a comparable conventional natural gas-
26
fired power plant. This eliminates the generation
of approximately 43,250 tons per year
of carbon dioxide (CO2) emissions, based on
the U.S. Environmental Protection Agency's
estimate of 1,135 pounds of CO2 generated
per MWh. In addition, the CPV facility has
very minimal water needs.
Facility Overview
J.E. (Jef) Freeman, Jr., vice president of development
at Cogentrix Energy Power Management,
the project's developer, told POWER
in September that a hydraulic system rotates
and tilts the assemblies throughout the day so
the surface of each panel maintains an optimal
angle with the sun.
" Another functional benefit of this design
is that the CPV system makes efficient use
of the available land, " Freeman said. " One
MW of rated capacity is installed on 7 acres,
compared to the approximately 8 to 10 acres
typically needed for other solar technologies.
The CPV technology is also easier to permit
and install, with no special grading, water
use, or other site treatment, minimizing the
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impact on the local natural environment. "
The CPV solar trackers are Amonix 7700
models, each featuring the company's proprietary
module assembly mounted on a support
column, Each tracker assembly is 70
feet wide by 50 feet high and contains 7,560
Fresnel lenses that concentrate sunlight approximately
500 times onto multi-junction
solar cells manufactured by Boeing-Spectrolab.
A hydraulic system supplied by Hawe
Hydraulics North America rotates and tilts
the assembly throughout the day so the surface
of each panel maintains an optimal angle
with the sun. Each tracker has its own inverter
(manufactured by Solectria Renewables)
that converts DC power output from the solar
cells to AC power. As an added bonus, the assembly's
modular design will easily accommodate
future cell technology updates.
Major contractors for the project were
Mortenson Construction (general contractor/construction
manager), Stantec (lead
design firm), and Ampirical Solutions
(electrical switchyard engineering, procurement,
and construction contractor).
POWER | December 2012
http://www.powermag.com
POWER December 2012

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