SCHOTT PTR®70 ReceiverThe Next Generation

new absorber coating – innovative glass-to-metal seal

patented bellow design – unique quality assurance system

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Energy in abundance.

How Parabolic Trough Power Plants work.Concentrated Solar Power (CSP) plants use steam to produce energy, in

a similar manner to conventional steam power plants. The key difference

is that CSP plants use emission-free, clean solar radiation to produce

heat instead of fossil or nuclear fuels. And unlike other CSP technologies,

parabolic trough power plants are proven and ready for use today. In

order to achieve the necessary temperatures, solar radiation is concentrat-

ed in parabolic trough arrays. These troughs are more than 400 meters

(1,300 feet) in length and are made of parabolical shaped mirror seg-

ments. The troughs track the sun over the course of the day and focus

the solar radiation along the focal point of the mirrors onto specially coat-

ed, evacuated receiver tubes that convert solar radiation into heat. A heat

transfer fluid, which is circulating through the receiver, is heated up to

400 °C (750 °F) and then used to generate steam.

SCHOTT Solar – Technology and Market Leader in Solar Receivers.The receiver, being the key component of a CSP plant, has a decisive

influence on the overall efficiency of the plant. It must show high solar

absorptance as well as low thermal emittance. In both respects, the

SCHOTT PTR®70 Receiver delivers outstanding results.

Introducing the next generation of the

SCHOTT PTR®70 Receiver with new absorber coating.New absorber coating with emittance 10% and absorptance 95%

Crucial for the performance of the collector field are the optical properties

of the absorber coating. SCHOTT Solar has developed and patented a new

absorber coating with remarkable optical values and long-term thermal

stability. Heat loss measurements by NREL (US National Renewable Energy

Laboratory) have confirmed emittance values of 10% at working temper -

ature (400 °C/750 °F), thus corresponding to a heat loss of only ~ 250 W/m,

in comparison to 350–450 W/m for other receivers. This contributes signif-

icantly to lower levelized costs of electricity and maximized output.

Innovative glass-to-metal seal

To minimize heat conduction losses, the absorber is usually insulated with

vacuum enclosed by a glass tube. The durability of the vacuum depends

on the mechanical strength and temperature resistance of the glass-to-

metal seal. Due to the combination of materials with matching coefficients

of thermal expansion, the glass-to-metal seal of the SCHOTT PTR®70

Receiver can handle dramatic temperature changes and ensures vacuum

stability. For maximum quality assurance, every single glass-to-metal seal

at SCHOTT Solar undergoes a thermal shock test.

Quality without compromise.The certified state-of-the-art productionfacilities for SCHOTT Solar® receivers in Germany, Spain and the USA have a globally installed capacity of 1 GW per year. Due to a unique quality assur-ance system with specially developed and complex measuring technology, SCHOTT Solar can provide products of consistently high quality across all production facilities.

Solarfield

Storage

Steam

Turbine

Condenser

Receivers

Parabolic mirrors

Heat Transfer Fluid

Generator

Cooling tower

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High-quality glass with anti-reflective coatings

The glass tubes of the receivers are usually coated with anti-reflective

(AR) films for improved solar transmittance. However, the weak point of

most AR-coatings is their low adhesion to the borosilicate glass. Due to a

patented production process, SCHOTT Solar has been able to introduce

a composition of the AR-layer with maximum adhesion and long-term

abrasion resistance, achieving transmittance values of more than 96%.

Improved bellow design

The patented bellow design by SCHOTT Solar increases the active aperture

area of the receiver to more than 96% of the total area, which is at least

2% more compared to other designs. Furthermore, by integrating the

getter material in the bellow and thus the coolest position of the receiver,

the full getter capacity can be utilized. This increases the lifetime of the

receiver up to 30% in comparison to other designs where the getter is

positioned on the absorber tube.

Technical specification – SCHOTT PTR®70 with new absorber

coating

Components Specification

Dimension •length:4,060mmat20°Cambienttemperature(159.8in.at68°F)•aperturelength:96% of the bulk length

at working temperature (300 °C/572 °F)

Absorber •outerdiameter:70mm/2.75in.•steeltype:DIN1.4541orsimilar•solarabsorptance: ISO 95%; ASTM 95.3%

•thermalemittance(atapprox.400°C/approx.752°F): 10%

Glass envelope •borosilicateglass•outerdiameter:125mm/4.9in.•antireflectivecoating•solartransmittance: 0.96

Vacuum •gaspressure10–3 mbar

Operating pressure •40 bar (absolute)

Durable glass-to-metal seal material combination with matching coefficients of thermal expansion

AR-coated glass tube ensures high transmittance and high abrasion resistance

Vacuum insulation minimized heat conduction losses

A well-established & quality- oriented partner.As a fully owned subsidiary of the global SCHOTT group, SCHOTT Solar builds on solid know-how and a strong financial backing, giving all customers the security to deal with a well-established, quality-oriented company. Whatever the future holds™.

New absorber coating achieves emittance <_10% and absorptance >_95%

Improved bellow design increases the aperture length to more than 96%

SCHOTT Solar CSP GmbH

Erich-Schott-Str. 14

95666 Mitterteich, Germany

Phone: +49 (0) 9633 80-291

Fax: +49 (0) 3641 2888-9231

csp@schottsolar.com

www.schottsolar.com

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