Concentrated Solar Power (CSP): Millions in Losses With Wrong Components

By Flabeg Holding Gmbh, PRNE
Monday, February 28, 2011

NUREMBERG, Germany, March 1, 2011 - According to calculations by DLR (German Aerospace Center) the increase
in yield resulting from annealed parabolic mirrors over a period of 25 years
amounts to more than seven million Euros. This is based on independent
figures and on the company's practical experience with more than seven
million solar mirrors that have been installed in the field for 30 years

In the industry it is discussed whether CSP solar mirrors made from
tempered or annealed glass achieve a better overall performance.
Manufacturers of tempered mirrors advertise lower costs for mirror
replacement. This calculation fails to take account however of the higher
plant yield that solar mirrors made of annealed glass achieve owing to their
better precision collector interception.

The key parameters for the yield of a CSP plant are the bending
properties of the mirrors. The basis for assessing the bending properties of
a solar mirror is the focus deviation (FDx). This measures the frequency
distribution of the real focus deviation in transversal (x) direction of the
reflected beam from the ideal focul line of the collector parabola.
Consequently, the lower the FDx value, the higher the plant yield. According
to the calculations of the DLR each millimetre of decreased scattering loss
amounts to an additional plant yield of 11.25 million Euros[1] over a period
of 25 years.

Based on these data, FLABEG Holding GmbH, the market leader in the field
of glass finishing and the leading international manufacturer of solar
mirrors has made the following calculation:

Yield and cost summary for a 50 MW plant with 23,000 tubes and 200,000

                               Annealed             Tempered

    Additional yield due to    + 7,875.000 EUR[1]              0
    better precision
    collector interception
    Costs for mirror               - 650,000 EUR    - 42,500 EUR
    replacements due to
    glass breakage
    Costs for absorber tube         - 65,000 EUR               0
    replacements due to
    glass breakage
    Total                        + 7,160.000 EUR    - 42,500 EUR

    Additional yield of the plant with annealed solar mirrors after
    25 years:

    7,117,500 EUR

Bases of calculation:

Average mirror breakage rate: annealed 0.20 %[2], tempered 0.01 %[3]
Average absorber tube breakage rate: annealed 0.025 %[2], tempered 0 %[3]
Precision rate / focus deviation: annealed FDx < 8 mm[4], tempered FDx < 8.7

[1] Mean values according to calculations by the German Aerospace Center,
reference values: plant capacity 50 MW, period of observation 25 years,
nominal glass thickness 4 mm

[2] Average values according to KJC/Harper Lake, period of observation
10 years, nominal glass thickness 4 mm

[3] Tempered glass manufacturer's indications

[4] Current average focus deviation of FLABEG parabolic solar mirrors

The result shows that during long-term observation, the annealed solar
mirrors are markedly more profitable: More than seven million Euros of
additional plant yield is achieved over the period of 25 years.

Axel Buchholz, CEO of FLABEG Holding GmbH, is able to confirm this
calculation based on independent figures from his own practical experience:
"Competitors advertise with extrapolations. In contrast, our solar mirrors
have been in the field for 30 years already and have proven their durability
and constantly high performance".

Another item of practical experience to be borne in mind: "Glass breakage
generally arises only at the corners or edge of a mirror. Tempered glass
shatters into a thousand individual pieces in this case, which may result in
considerable damage to other components in the field. Our annealed mirrors on
the other hand continue to remain operational".

FLABEG, founded in 1882, is an independent company with 13 facilities in
Europe, America and Asia. FLABEG is active in the commercial sectors of
automotive mirrors, solar mirrors and technical glass; specializing in all
processes of glass finishing. As the pioneer of solar technology with a
worldwide network, FLABEG produces mirrors for all CSP-applications -
Parabolic Trough, Dishes, Tower and Linear Fresnel. Due to latest coating
technologies our solar mirrors are characterized by a reflectivity of more
than 95%. FLABEG sets technological standards in terms of the company's core
competencies - bending and coating.

    For further informations contact:

    Kerstin Kötter
    Head of Marketing & Communication
    FLABEG Holding GmbH
    Waldaustr. 13
    90441 Nürnberg
    Phone: +49-911-96456-0
    Fax: +49-911-96456-465

For further informations contact: Kerstin Kötter, Head of Marketing & Communication, FLABEG Holding GmbH, Waldaustr. 13, 90441 Nürnberg, Phone: +49-911-96456-0, Fax: +49-911-96456-465, kerstin.koetter at

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