September 2011 - I-Micronews

S E P T E M B E R 2 0 1 1 I S S U E N ° 1 3
“Compared to the
more established
flat plate PV
technology, HCPV
likely has much
more headroom
for improving
efficiency
and cost,”
says Milan Rosina,
Yole Développement.
throw at the work. Garboushian ticks off potential
ways to gain a few percentage points improvement
across almost all the various components in the
systems - from better multijunction cell efficiency, to
better pitch angles and more accurate facets in the
Fresnel lenses, up through more accurate alignment
in the balance of systems, which could together
perhaps add up to as much as 50% improvement
overall.
Key to much of this improvement is the growth and
increasing maturity of the supply chain. “While the
solar supply chain continues to mature, there has
been no shortage of innovation,” he says, noting that
the optics and components are constantly improving.
On the cell side, Garboushian notes that the best
cells are already 5% to 10% better than those
from some other suppliers, and spectral tuning for
particular locations can add up to another 5% to 10%
improvement in energy generation. But going beyond
three junction cells won’t be an easy step for the
optics and the rest of the system.
Garboushian and Amonix have been making
concentrating solar for some 20 years, and were
among the pioneers of the big move from silicon to
compound semiconductor triple junction cells for the
boost in efficiency that did much to help create a viable
HCPV market not so very long ago. The company’s
early 7.8 MW-scale HCPV project with Guascor
Foton in Spain in 2006-2008 used silicon cells, and
depended on European government subsidies to be
economic. Working with Emcore and Spectrolab to
stabilize the process, prove the cell reliability, and
redesign the rest of the system took a year, but it cut
costs roughly in half and enabled output to jump from
25kW to 37kW.
SolFocus permitting 30MW project, plans
to double production capacity to 100MW
SolFocus is stepping up to tens-of-megawatt projects
as well, with a 30MW power supply agreement
from San Diego Gas & Electric now in the permitting
process, which may be ready to start installation later
this year. Nancy Hartsoch, VP of marketing, says the
company also plans to increase its production capacity
from the current 50MW to 100MW this year, by adding
a second $10 million robotic assembly cell at its
assembly facilities in China.
The San Jose, California, company has installed
projects in a dozen countries, most so far relatively
small, essentially to test the HCPV performance
under various conditions at different sites around the
world. Recent larger US installations include the 1MW
Victor Valley College project, the 1MW Nichols Farm
pistachio processing plant, and the ~0.5MW Coachilla
water reclamation plant, the latter two particularly
significant because they were put together by heavy
weight project managers Bechtel and Johnson
Controls, suggesting these big companies think it
worthwhile to learn the HCPV business on these
relatively small installations for its future potential.
Another big step: the first performance warranty
insurance for HCPV from Munich Re.
Though the utility market will be the bigger one,
Hartsoch also sees a strong market for HCPV in this
type of distributed generation, for the educational,
agricultural processing, and water treatment markets,
all users that tend to have big electrical bills, extra
land already, and renewable energy goals.
Like most of the other companies in this young
technology, SolFocus designed and originally made
not only its own components, but even much of its
custom production equipment, but as volume has
increased, it has outsourced all production. The
company’s founders decided from the beginning to
focus on proven glass, aluminum and steel materials,
and on designing for manufacturability as the best
way to create a low cost product. Major parabolic
dish glass supplier Flabeg makes the mirrors, using
SolFocus-designed equipment to slump a square
mirror. One of the big electronics assembly houses
assembles the receiver units and optical cones, and
an assembly company in China puts together the final
systems, using a monster press to stamp out the
backpan in one piece, and a three-robot cell designed
to SolFocus specifications by a company from the
automotive assembly industry.
Hartsoch argues that the company’s unique optics
design may add complexity, with its third non-imaging
optic that focuses the light down through a prism to
more evenly illuminate the cell, the unusually wide
1.6° acceptance angle allows more margin for some
misalignment in assembly, installation and tracking.
“You can lose a lot of energy for every 0.25° smaller
acceptance angle,” she argues.
The new generation systems just introduced swap out
the cells for the next generation of more efficient ones,
to boost panel efficiency to 29%, and redesign the
modules for easier field assembly to reportedly reduce
installation costs by cutting field installation time by
half. The new modules add more panels per tracker,
for fewer total trackers, and pre-assemble more panels
into units, for fewer units per tracker to install, and no
need for alignment in the field. The electronics are also
now premounted on the tracker head, so no electronics
assembly is required in the field. Hartsoch says that cut
field assembly time in half. “And that’s with engineers,”
she quips. “In the field with construction people it
should be more than a 50% reduction in assembly
time.” The relatively light dish units can be installed
with cranes or scaffold forklifts, and can go on spread
foundations or steel piers instead of concrete and in
problematic soils like sand or landfills.
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