Sun & Wind Energy 8/2011

Helmut Zangl, Managing Director of EuroSun Vacuum-Solar-Systems talks about its single-glass tubes at Intersolar. Photos (2): Wilhelm Breuer

OptimisedManufacturers of vacuum tube

collectors did not have much new to

put on show this year. Currently, the

focus is on improving the collectors’

appearance.

optics

87

Most of the vacuum tube collectors on the global market have double-walled glass tubes. The evacuated space between the

tubes insulates the absorber inside, the way a Thermos does. The tubes are produced in China. Chinese manufacturers have recently improved their absorber coatings. Along with the traditional alumini-um and aluminium nitride coatings, more and more tubes with additional coats of copper and stainless steel are on the market (see also article on page 80). European man ufacturers are increasingly using these tubes too (see table on page 90).

Kt Solar, the collector brand of Italy’s Turco Group S.r.l., also uses such tubes. The company has devel-oped a new collector series called the Sky Pro 1800. Kt formerly used 1,500 mm long tubes, but the Sky

Solar thermalVacuum tubeS

88

Solar thermal Vacuum tubeS

groundwater. In summer, groundwater cools the building. AMK built itself a generous headquarters. Along with 1,800 m2 of office space, the building has 2,500 m2 for storage and production. Initially, the company will lease a further 7,500 m2. If AMK grows as planned, in 10 years it will be using 10,000 m2 for production and storage.

Another new development at AMK is the SRCC test for its OWR collectors, which do not have CPC re-flectors. In addition, the company now offers collec-tors with black frames which blend in better with rooftops. Sales Manager Uwe Karl has announced the launch of a completely new collector for next year.

FK Solartechnik GmbH of Germany will also launch an improved vacuum tube collector next year. This

Sun & Wind Energy 8/2011

The new Sky Pro from Kt Solar is equipped with 1,800 m long tubes. Photo: Kt Solar

Pro is equipped with 1,800 mm tubes. This increases the stagnation temperature of the new design over its predecessor, the Sky CPC, from 249 to 259 °C.

Polish manufacturer Watt Sp. z.o.o. also offers something new. Last November, the company set up a new semi-automated line for vacuum tube CPC collectors.

In June, Switzerland’s AMK-Collectra AG moved from the town of Sevelen, near the Liechtenstein bor-der, to the town of Buchs, a few kilometres to the north. AMK’s building was built in accordance with the Swiss energy label Minergie. It has an active con-crete core combined with a heat pump, backed up by AMK collectors which extract thermal energy from

Sun & Wind Energy 8/2011

FK Solartechnik’s Sales Man-ager Michael Jaster explains the design of the heat pipes in the Solinas 3 collector. Photo: Jens-Peter Meyer

Hejia Solar covers its vacuum tubes with a glass plate. Photo: Jens-Peter Meyer

year, the company has added a feature to improve the visual appearance of the FK Solinas 3 heat pipe col-lector. A new cover fitted between adjacent collectors creates a uniform appearance when several collectors are connected to form a single field. Special insulat-ing elements for the interface between the collectors also reduce thermal losses. Like most manufacturers, FK Solartechnik uses mineral wool insulation in its collectors. What sets FK’s insulation apart, however, is a highly temperature-resistant pressed mineral wool with a 35 % better U-value than the insulation in a typical flat plate collector.

Chinese manufacturer Hejia Solar Energy Co., Ltd. also presented a new idea at Intersolar Europe. The vac-uum tubes in its collectors are placed behind a glass

Sun & Wind Energy 8/201190

Solar thermal Vacuum tubeS

Double glass tubes

Single glass tubes

Dies ist die Überschrift zu Tab in Datei:

st_jpm_Marktü_Vakuumr_double glass.xls

Manufacturer Product name Kind of tubes Number of tubes

Tube diameter [mm]

Tube length [mm]

Thickness inner tube [mm]

Thickness outer tube [mm]

Kind of glass τ [%]Absorption layer α [%] ε [%] Tube material

Manifold material

Manifold insulation

Thermal con-duction sheet

Reflector material

Testing norm μ0 1 a1 [W/m²·K] 1

a2 [W/m²·K²] 1

Stagnation temperature [°C]

Warranty[years]

Available in which countries

Calpak, Greece VTN U-type with CPC reflector

10 up to 16 47 1,500 1.6 1.6 borosilicate >90.1 3 layers >92.2 <7.5 copper copperglass wool and polyurethane

aluminium aluminium EN12975 3,4 0.665 0.700 0.036 227 10 worldwide

Camel Solar LTD, Macedonia

Vacuum ST-15

U-type without CPC reflector

10 / 15 58 1,800 1.7 1.7 borosilicate 91.5 3 layers95 up to 96

4 up to 5 copper aluminium rock wool aluminium - EN12975 6 n/a n/a n/a n/a 10 Serbia, Macedonia

Consolar, Germany

Tubo 12 CIU-type with CPC reflector

6 47 1,803 1.5 1.7 borosilicate 92 SC-coating93 up to 94

5 up to 6 Cu-Ni copper air aluminium aluminium EN12975 3 0.620 0.395 0.020 250 10 Europe

GREENoneTEC, Austria

VRK 10U-type with CPC reflector

10 / 14 47 1,520 1.6 1.6 borosilicate >91 Al-N 96 6 copper copper rock wool aluminium aluminium EN12975 3 0.605 0.85 0.01 286 5 worldwide

Hiramrut, IndiaSun-Ray water in glass 12 up to 37 47 1,800 1.6 1.6 borosilicate >92 Cu-S-Al n/a n/a glass n/a polyurethane - n/a MNRE 5 >0.45 1.760 2.120 200 15

IndiaSun-Ray water in glass 27 70 2,100 1.6 1.6 borosilicate >92 Cu-S-Al n/a n/a glass n/a polyurethane - n/a MNRE 5 >0.45 1.130 3.620 200 15

Huayang New Energy, China

hpheat pipe without CPC reflector

12 58 1,800 1.6 1.8 borosilicate 94 AL-SS-CO 94 n/a n/a n/a n/aaluminium alloy

rock wool EN12975 3,4,7 n/a n/a n/a 200 5 worldwide

Kt Solar, Italy Sky Pro 1800

U-type with reflector

10/12/14/16/18/20

58 1,800 1.6 1.7 borosilicate n/a AINx/Cu >94.5 <6.5 copper copper mineral wool n/a aluminium EN12975 3 0.718 1.051 0.004 259 10worldwide

Sky CPC 58U-type with reflector

8 /10/12/14/16/21

58 1,500 1.6 1.7 borosilicate n/a AINx/Cu >94.5 <6.5 copper copper mineral wool n/a aluminium EN12975 3 0.718 0.974 0.005 249 10

Ritter Solar, Germany

CPC 6/12/18 INOX

U-type with CPC reflector

6/12/18 47 1,500 1.6 1.6 borosilicate 91 AlN >94 < 6 stainless steelstainless steel /copper

rock wool aluminium aluminium EN12975 3,4 0.642 0.890 0.001 272 10worldwide

CPC 16/20 w INOX

U-type with CPC reflector

16/20 47 1,800 1.6 1.6 borosilicate 91 AlN >94 < 6 stainless steelstainless steel /copper

rock wool aluminium aluminium EN12975 3,4 0.644 0.749 0.005 301 10

Sunshore, China

Non pressure collector

water in glass 30 58 1,800 1.6 1.6 borosilicate ≥91 AlN/Al ≥86 ≤8 glass n/a polyurethane - aluminium EN12975 3 0.752 1.613 0.000 230 3 worldwide

Thermics, Italy 10 DTH-CPCcoaxial copper pipe with CPC reflector

10 58 1,800 1.6 2.2 borosilicate 91 Cr-AlN/Cu 95 5 copper aluminium rock wool aluminium aluminium EN12975 3 0.675 1.540 0.003 313 10 Europe

Unasol, Brazil 2AP30

heat pipe without CPC

30 58 1,800 1.8 1.6 borosilicate n/a AlN/Al >92 <8 copper aluminium glass wool aluminium - EN12975 3 0.687 1.505 0.011 245 10Brazil

AP20heat pipe without CPC

20 58 1,800 1.8 1.6 borosilicate n/a AlN/Al >93 <9 copper aluminium glass wool aluminium - EN12975 3 0.687 1.505 0.011 245 10

Vermos, Czech Republic

VU10-CPCU-type with CPC reflector

10 47 1,500 1.6 2.2 borosilicate 91 AINx/Cu 95 5 copper copper Armaflex copper aluminium n/a 0.650 1.210 0.011 210 8Europe

VU16-AU-type without reflector

16 47 1,500 1.6 2.2 borosilicate 91 AINx/Cu 95 5 copper copper Armaflex copper - n/a 0.810 1.840 0.009 210 8

Watt, Poland CPC 9 plus

U-type with CPC reflector

9 47 1,800 1.6 1.6 borosilicate 89 AlN 95.5 5.5 glass copper glass wool n/a aluminium EN12975 3 0.611 0.840 0.005 303 10Europe

CPC 15U-type with CPC reflector

15 47 1,800 1.6 1.6 borosilicate 89 AlN 95.5 5.5 glass copper glass wool n/a aluminium EN12975 3 0.573 1.240 0.006 304 5

Manufacturer Product name Kind of tubesNumber of tubes

Tube diam-eter [mm]

Tube length [mm]

Thickness tube [mm]

Kind of glass τ [%]Absorber sheet

Absorber layer α [%] ε [%]

Tube material

Tube absorber sheet connection

Material manifold

Manifold insulation

Tested for conformity with which standard/norm μ0 1 a1 [W/m²·K] 1

a2 [W/m²·K²] 1

Stagnation temperature [°C]

Warranty [years]

Available in which countries

3U Solar / EuroSun 5,

Germany

HP 65/30 heat pipe 20 / 30 65 1,980 2 borosilicate n/a copper tinox >95 <5 n/a ultrasoniccopper and aluminium

mineral wool EN12975 6 0.826 2 1.62 2 0.001 2 290 5Europe

DF 120/6 8 direct flow 6 120 2,950 3.5 borosilicate n/a copper tinox >95 <5 n/a ultrasoniccopper and aluminium

mineral wool EN12975 6 0.841 1.360 0.002 290 5

AkoTec, Germany

OEM Vario 3000

direct flow 30 56 2,000 1.8 soda lime 96 copper tinox 95 5 copper ultrasonic copper Armaflex/Kaiflex EN12975 3,4 0.749 1.485 0.002 192 10worldwide

OEM Vario 3000-30 hp

heat pipe 30 56 2,000 1.8 soda lime 96 copper tinox 95 5 copper ultrasonic copper Armaflex/Kaiflex EN12975 3,4 0.683 1.489 0.000 160 10

Elco, GermanyAuron DF 15 / Auron DF 20

direct flow 15 / 20 70 1,790 n/a borosilicate n/a aluminiumhighly selective

n/a n/a copper clamp ring copper rock wool EN12975 3 0.821 10 2.824 10 0.0047 10 206 5 Europe

Hewalex, PolandKSR10 / 2xKSR10

direct flow 10 / 20 56 2,000 1.8 borosilicate 96 copper tinox 95 4 copperultrasonic welding

brass rock wool EN12975 3 0.78 1.27 0.0012 303 5 Europe

Kingspan Renewables, Northern Ireland

HP250 heat pipe 30 65 1,960 1.5 soda lime 92 copper tinox 95 5 copper ultrasonic copper melamine foam EN12975 3 0.755 1.060 0.008 217 20 9 worldwide

Varisol direct flow 1 up to 150 7 65 1,950 1.5 soda lime 92 copper tinox 95 5 copper ultrasonic PPS n/a EN12975 3 0.783 1.061 0.023 240 20 9worldwide except US

Sunda, ChinaSeido1-16AS heat pipe 8/16 100 2,000 2.8 borosilicate >90 aluminium

selective coating

>92 <8 copper pressed copper polyurethane EN12975 3 0.694 2.118 0.004 235 5worldwide

Seido2-16 direct flow 8/16 100 2,000 2.8 borosilicate >90 aluminiumselective coating

>92 <8 copper pressed copper polyurethane EN12975 3,4 0.798 0.994 0.010 276 5

1 relating to aperture, 2 manufactured under Apricus license; 3 Solar Keymark labeled; 4 SRCC labeled; 5 MNRE labeled; 6 Solar Keymark certification is in progress; 7 Golden Sun labels

1 relating to aperture, 2 data for 30 tube collectors; 3 Solar Keymark labeled; 4 SRCC labeled; 5 EuroSun is part of the 3U Group ; 6 Solar Keymark certification is in progress; 7 number of tubes is variable; 8 also tubes with 100 mm diameter available; 9 conditions apply; 10 data for 20 tube collectors

Sun & Wind Energy 8/2011 91

Source: company data

Manufacturer Product name Kind of tubes Number of tubes

Tube diameter [mm]

Tube length [mm]

Thickness inner tube [mm]

Thickness outer tube [mm]

Kind of glass τ [%]Absorption layer α [%] ε [%] Tube material

Manifold material

Manifold insulation

Thermal con-duction sheet

Reflector material

Testing norm μ0 1 a1 [W/m²·K] 1

a2 [W/m²·K²] 1

Stagnation temperature [°C]

Warranty[years]

Available in which countries

Calpak, Greece VTN U-type with CPC reflector

10 up to 16 47 1,500 1.6 1.6 borosilicate >90.1 3 layers >92.2 <7.5 copper copperglass wool and polyurethane

aluminium aluminium EN12975 3,4 0.665 0.700 0.036 227 10 worldwide

Camel Solar LTD, Macedonia

Vacuum ST-15

U-type without CPC reflector

10 / 15 58 1,800 1.7 1.7 borosilicate 91.5 3 layers95 up to 96

4 up to 5 copper aluminium rock wool aluminium - EN12975 6 n/a n/a n/a n/a 10 Serbia, Macedonia

Consolar, Germany

Tubo 12 CIU-type with CPC reflector

6 47 1,803 1.5 1.7 borosilicate 92 SC-coating93 up to 94

5 up to 6 Cu-Ni copper air aluminium aluminium EN12975 3 0.620 0.395 0.020 250 10 Europe

GREENoneTEC, Austria

VRK 10U-type with CPC reflector

10 / 14 47 1,520 1.6 1.6 borosilicate >91 Al-N 96 6 copper copper rock wool aluminium aluminium EN12975 3 0.605 0.85 0.01 286 5 worldwide

Hiramrut, IndiaSun-Ray water in glass 12 up to 37 47 1,800 1.6 1.6 borosilicate >92 Cu-S-Al n/a n/a glass n/a polyurethane - n/a MNRE 5 >0.45 1.760 2.120 200 15

IndiaSun-Ray water in glass 27 70 2,100 1.6 1.6 borosilicate >92 Cu-S-Al n/a n/a glass n/a polyurethane - n/a MNRE 5 >0.45 1.130 3.620 200 15

Huayang New Energy, China

hpheat pipe without CPC reflector

12 58 1,800 1.6 1.8 borosilicate 94 AL-SS-CO 94 n/a n/a n/a n/aaluminium alloy

rock wool EN12975 3,4,7 n/a n/a n/a 200 5 worldwide

Kt Solar, Italy Sky Pro 1800

U-type with reflector

10/12/14/16/18/20

58 1,800 1.6 1.7 borosilicate n/a AINx/Cu >94.5 <6.5 copper copper mineral wool n/a aluminium EN12975 3 0.718 1.051 0.004 259 10worldwide

Sky CPC 58U-type with reflector

8 /10/12/14/16/21

58 1,500 1.6 1.7 borosilicate n/a AINx/Cu >94.5 <6.5 copper copper mineral wool n/a aluminium EN12975 3 0.718 0.974 0.005 249 10

Ritter Solar, Germany

CPC 6/12/18 INOX

U-type with CPC reflector

6/12/18 47 1,500 1.6 1.6 borosilicate 91 AlN >94 < 6 stainless steelstainless steel /copper

rock wool aluminium aluminium EN12975 3,4 0.642 0.890 0.001 272 10worldwide

CPC 16/20 w INOX

U-type with CPC reflector

16/20 47 1,800 1.6 1.6 borosilicate 91 AlN >94 < 6 stainless steelstainless steel /copper

rock wool aluminium aluminium EN12975 3,4 0.644 0.749 0.005 301 10

Sunshore, China

Non pressure collector

water in glass 30 58 1,800 1.6 1.6 borosilicate ≥91 AlN/Al ≥86 ≤8 glass n/a polyurethane - aluminium EN12975 3 0.752 1.613 0.000 230 3 worldwide

Thermics, Italy 10 DTH-CPCcoaxial copper pipe with CPC reflector

10 58 1,800 1.6 2.2 borosilicate 91 Cr-AlN/Cu 95 5 copper aluminium rock wool aluminium aluminium EN12975 3 0.675 1.540 0.003 313 10 Europe

Unasol, Brazil 2AP30

heat pipe without CPC

30 58 1,800 1.8 1.6 borosilicate n/a AlN/Al >92 <8 copper aluminium glass wool aluminium - EN12975 3 0.687 1.505 0.011 245 10Brazil

AP20heat pipe without CPC

20 58 1,800 1.8 1.6 borosilicate n/a AlN/Al >93 <9 copper aluminium glass wool aluminium - EN12975 3 0.687 1.505 0.011 245 10

Vermos, Czech Republic

VU10-CPCU-type with CPC reflector

10 47 1,500 1.6 2.2 borosilicate 91 AINx/Cu 95 5 copper copper Armaflex copper aluminium n/a 0.650 1.210 0.011 210 8Europe

VU16-AU-type without reflector

16 47 1,500 1.6 2.2 borosilicate 91 AINx/Cu 95 5 copper copper Armaflex copper - n/a 0.810 1.840 0.009 210 8

Watt, Poland CPC 9 plus

U-type with CPC reflector

9 47 1,800 1.6 1.6 borosilicate 89 AlN 95.5 5.5 glass copper glass wool n/a aluminium EN12975 3 0.611 0.840 0.005 303 10Europe

CPC 15U-type with CPC reflector

15 47 1,800 1.6 1.6 borosilicate 89 AlN 95.5 5.5 glass copper glass wool n/a aluminium EN12975 3 0.573 1.240 0.006 304 5

Manufacturer Product name Kind of tubesNumber of tubes

Tube diam-eter [mm]

Tube length [mm]

Thickness tube [mm]

Kind of glass τ [%]Absorber sheet

Absorber layer α [%] ε [%]

Tube material

Tube absorber sheet connection

Material manifold

Manifold insulation

Tested for conformity with which standard/norm μ0 1 a1 [W/m²·K] 1

a2 [W/m²·K²] 1

Stagnation temperature [°C]

Warranty [years]

Available in which countries

3U Solar / EuroSun 5,

Germany

HP 65/30 heat pipe 20 / 30 65 1,980 2 borosilicate n/a copper tinox >95 <5 n/a ultrasoniccopper and aluminium

mineral wool EN12975 6 0.826 2 1.62 2 0.001 2 290 5Europe

DF 120/6 8 direct flow 6 120 2,950 3.5 borosilicate n/a copper tinox >95 <5 n/a ultrasoniccopper and aluminium

mineral wool EN12975 6 0.841 1.360 0.002 290 5

AkoTec, Germany

OEM Vario 3000

direct flow 30 56 2,000 1.8 soda lime 96 copper tinox 95 5 copper ultrasonic copper Armaflex/Kaiflex EN12975 3,4 0.749 1.485 0.002 192 10worldwide

OEM Vario 3000-30 hp

heat pipe 30 56 2,000 1.8 soda lime 96 copper tinox 95 5 copper ultrasonic copper Armaflex/Kaiflex EN12975 3,4 0.683 1.489 0.000 160 10

Elco, GermanyAuron DF 15 / Auron DF 20

direct flow 15 / 20 70 1,790 n/a borosilicate n/a aluminiumhighly selective

n/a n/a copper clamp ring copper rock wool EN12975 3 0.821 10 2.824 10 0.0047 10 206 5 Europe

Hewalex, PolandKSR10 / 2xKSR10

direct flow 10 / 20 56 2,000 1.8 borosilicate 96 copper tinox 95 4 copperultrasonic welding

brass rock wool EN12975 3 0.78 1.27 0.0012 303 5 Europe

Kingspan Renewables, Northern Ireland

HP250 heat pipe 30 65 1,960 1.5 soda lime 92 copper tinox 95 5 copper ultrasonic copper melamine foam EN12975 3 0.755 1.060 0.008 217 20 9 worldwide

Varisol direct flow 1 up to 150 7 65 1,950 1.5 soda lime 92 copper tinox 95 5 copper ultrasonic PPS n/a EN12975 3 0.783 1.061 0.023 240 20 9worldwide except US

Sunda, ChinaSeido1-16AS heat pipe 8/16 100 2,000 2.8 borosilicate >90 aluminium

selective coating

>92 <8 copper pressed copper polyurethane EN12975 3 0.694 2.118 0.004 235 5worldwide

Seido2-16 direct flow 8/16 100 2,000 2.8 borosilicate >90 aluminiumselective coating

>92 <8 copper pressed copper polyurethane EN12975 3,4 0.798 0.994 0.010 276 5

1 relating to aperture, 2 manufactured under Apricus license; 3 Solar Keymark labeled; 4 SRCC labeled; 5 MNRE labeled; 6 Solar Keymark certification is in progress; 7 Golden Sun labels

Vacuum tubeS

The roof-integrated collector from AkoTec also takes advantage of reflected light striking the back side of the absorber.

Sun & Wind Energy 8/2011

cover. The company did not reveal how it intends to ap-ply this system, but one possible use could be on the façades of tall buildings, where a cover could offer in-creased protection against high winds.

Wind resistant: flat roof installation for harsh conditions

There are also some new developments in single glass tube collectors. In these tubes, the absorber is inside of a single-walled vacuum tube. Such tubes therefore require a glass-metal transition.

Germany’s AkoTec has developed a roof-integrat-ed version of its vacuum tube collector. An aluminium sheet behind the tubes stands in for roof tiles, en-abling the collectors to be installed in the same plane as the roofing and ensuring harmonious integration of the collectors into the roof. Collectors with a back wall are already part of AkoTec’s product range. This is due to a unique characteristic of the Narva tubes used by AkoTec: their absorbers can be coated on both sides. This enables the vacuum tubes to absorb sunlight on their back sides as well. The back wall of the AkoTec roof-integrated collectors also contributes to this ef-

Sun & Wind Energy 8/2011 93

The direct flow, single-glass collector Varisol presented last year by Kingspan is made of individually assembled tubes on the roof only. Photo: Kingspan

fect. According to Sales Manager Katrin Müller, mea-surement data shows that the collectors are capable of up to 20 % greater yield.

Another innovation from AkoTec is an installation system for flat roofs optimised for high winds. Lateral spoilers ensure that the collector is pressed down on-to the flat roof in high winds. This eliminates the need for weights to keep collectors in place on the roof. This is important, of course, in locations subject to high winds, such as buildings more than 25 m high.

Jens-Peter Meyer

Further information:3U Solar Systemhandel AG : www.3usolar.de AkoTec Produktionsgesellschaft mbH: www.akotec.euAMK Collectra AG: www.amk-collectra.ch

Market leader in Europe.

Industrially manufacturedtop quality products.

Distribution exclusively to OEM partners.

www.ritter-gruppe.com

Ritter Energie- und Umwelttechnik GmbH & Co. KGKuchenäcker 2 · 72135 Dettenhausen · GermanyTel. +49 7157 5359 1200 · info@ritter-gruppe.com

Leading manufacturer ofevacuated tube collectors

Beijing Sunda Solar Energy Technology Co., Ltd.: www.sundasolar.comCalpak-Cicero Hellas S.A.: www.calpak.grCamel Solar LTD: v_ristov@hotmail.com (website in construction)Consolar Solare Energiesysteme GmbH: www.consolar.deElco (Ariston Thermo S.p.A. ): www.elco.netEuroSun Vacuum-Solar-Systems GmbH: www.euro-sun-solar.deFK Solartechnik GmbH: www.fksolar.deGREENoneTEC Solarindustrie GmbH: www.greenonetec.comHejia Solar Energy Co., Ltd.: www.hjsolar.comHewalex: www.hewalex.plHiramrut Energies Pvt.Ltd: www.sunray.co.inKingspan Renewables Ltd.: www.kingspansolar.comKt Solar (Turco Group S.r.l.): www.ktsolar.comRitter Energie- und Umwelttechnik GmbH & Co. KG: www.ritter-gruppe.comSunshore Solar Energy Co.,Ltd :www.sunshore.cnThermics srl: www.thermics.itUnasol: www.unasol.com.brVermos s.r.o.: www.vermos.czWatt Sp. z o.o.: www.watt.pl