SOLAR THERMAL quality - Sun & Wind Energy THERMAL 29 a question of quality and aesthetics A lmost everywhere in the world, making use of solar heat means installing systems which are

S O L A R T H E R M A L

a question of qualityGravity systems worldwide:

Street sales in TurkeyPhoto: Auraset

Worldwide, more than 90 % of all solar systems for domestic

water heating are based on the thermosiphon principle. But none-

theless these systems vary widely from region to region.

Export worldwide: a thermo-siphon system of Chromagen in Guatemala Photos (2): Chromagen

Aesthetically designed system with flat, integrated tanks.Photo: Dagsan

Sun & Wind Energy 1/2006


29

a question of quality

and aesthetics

Almost everywhere in the world, making use of solar heat means installing systems which are based on gravity circulation. In January of this year, Sun & Wind Energy sent a questionnaire to more than 60 com-panies all over the world. Of the replies, 31 met our criteria for inclusion in this survey:

The companies had to conduct their own production and to export thermosiphon systems. As expected, the strongest feedback came from Europe and included no less than nine Turkish and eight Greek companies. On the other hand, no replies were received from Italy and France and only one from Spain and one from Portugal – a result which mirrors the signifi cance of solar heating in these countries. China, the global leader in this tech-nology, is represented by three companies which to-gether cover about 13 % of the market. This is a low re-sponse which is partly infl uenced by the fact that, to date, the Chinese have given little attention to export.

Figure 2 shows the 20 companies in the survey with the highest turnover. The Australian manufacturer Sola-hart leads the turnover league, followed by Chromagen from Israel and Jiangsu Sunrain Solar Water Heater from China. All the manufacturers belong to the category of small to medium-sized businesses and are chiefl y active in the solar sector. Two exceptions here are Schüco, a large German manufacturer of building facades, win-dows and doors, and Gamesa, the Spanish manufac-turer of wind turbines.

In 2005, all the respondent companies reported a good growth in turnover. The most positive business developments were experienced by Austrian manufac-turers with an average plus of 31 %, in Turkey with a plus of 28 % and in China with a plus of 27 %. Average double-fi gure growth was also reported in Australia and in Israel. At the lower end of the scale came Greece (+ 8 %) and Brazil (+ 7.5 %). All companies expect even stronger growth for the current year.

In all countries, the export sector is gaining in impor-tance: In addition to an upturn in solar thermal energy in the southern European countries, the companies’ sales

experts also expect booming markets in the Middle East and North Africa. Calpak, for instance, is active in Mo-rocco, Tunisia, Yemen and Lebanon. The Greeks have their sights on Saudi Arabia as an important future mar-ket. »We expect a positive market trend in Europe and

North Africa«, says Panayis Konstantinidis, Managing Director of Calpak. Eraslan is strongly active in the re-gions bordering on Turkey: to the south in Syria and Iraq, to the east in Iran, Afghanistan, Pakistan and Georgia, and to the west in Rumania, Bulgaria and the Balkan states.

But prices are under pressure everywhere due to the rising costs of raw materials (copper, steel and plastics) (Fig. 1). In 2005, more than half of the surveyed compa-nies introduced a moderate price rise of up to 5 %, while almost a third raised their prices by up to 10 %. The ma-jority of the respondents expect a similar trend for the coming year. But there is one exception: the Turkish market is currently experiencing above-average price increases of up to 20 %. However, in the medium term, prices should fall, with almost all companies expecting lower prices in fi ve years’ time. Only Solahart is more cautious in its forecast and expects a stable price level.

The majority of the companies manufacture both the collector and the storage tank themselves and mar-ket the systems both under their own brand names and as OEM products. The Central European producers and Gamesa manufacture only the collectors and purchase the tanks from specialists. The Turkish company Kodsan, on the other hand, is a pure storage tank specialist which obtains its collectors from several Turkish manufactur-ers. Table 2 on page 38/39 sets out the technical product details for all 31 companies.

Fig. 1: Price development of thermosiphonic domestic water heaters in 2005 and forecast for 2005.Source: Manufacturer‘s instructions

Architectonic solution for a single family home in IsraelPhoto: Chromagen

Fig. 1: Price development

0 10 20 30 40 50 60 70 80

the prices decreaseup to 10 %

the prices increaseup to 5 %

the prices increaseabout 6 up to 10%

the prices increaseabout 11 up to 20 %

the prices increaseabout 20 %

2006

2005

%

Future solutions: quality and aesthetics gain in importance also in TurkeyPhoto: Ezinc



Eastern Mediterranean region traditionally strong

Besides China, the eastern Mediterranean region is tra-ditionally the area with the greatest prevalence of ther-mosiphon solar domestic water heating systems (Fig. 3). In 2004 in Israel, for instance, some 380,000 m2 of collector area (266 MW) was installed. This gives the nation almost the highest pro capita density of such systems anywhere in the world. It is outdone only by Cyprus: on this Mediterranean island more than 90 % of households have a solar thermal system. Turkey achieved the strongest growth in the region in 2004, with 480,000 m2 (336 MW), while Greece, too, is a ma-jor solar heating player with 215,000 m2 of installed col-lector area (151 MW).

»On the Mediterranean coast of Turkey, 80 % of the installed solar hot water units are atmospheric open-loop systems, while in central Turkey, 80 % of the sys-tems sold are atmospheric closed-loop systems«, com-ments Utku Tansug (Export Director of Auraset). The company concentrates on export and produces about

50 % closed-loop pressurised systems; it also supplies pumped solar units which to date form a niche product in Turkey.

Eraslan Solar produces closed-loop systems only. At-mospheric systems account for more than three-quar-ters of production (180,000 solar collectors per year). The company‘s major hit, with a share of 45 %, is the Sunlight system in which the storage tank is installed vertically. This is followed by the Moonlight system which features an additional cold water tank. The Daylight sys-

Tuma, BrazilSammler,Greece

Solimpeks, TurkeyAuraset, Turkey

Enalter, BrazilDimas, Greece

Kodsan, TurkeyCalpak, Greece

Kuzey Enerji, TurkeySunpower, ChinaGasokol, Austria

Nobel Xilinakis, GreeceStibetherm SA, Greece

Sun Master, AustriaEraslan, Turkey

Ezinc, TurkeyLinuo Paradigma, China

Jiangsu Sunrain Solar Water Heater, ChinaChromagen, IsraelSolahart, Australia 50.4 (170)

2 (30)

3 (100)4 (50)

4.6 (25)5 (70)

6 (40)10 (35)

14 (210)16 (700)

25 (50)32 (230)

4.6 (70)4.3 (53)

2.6 (26)2.5 (60)

1.7 (23)1.5 (15)1.4 (20)

0 5 10 15 20 25 30 35 40

Turnover 2005 in Mio. € (Employees)

13 (180)

Fig. 2: The top companies in terms of turnover with num-ber of employees in the solar business (in brackets). In each instance, the turnover in the solar sector is indicated, whereby most of the compa-nies are chiefl y active in the solar sector. Quoted amounts in US $, AUD and CAD were converted to Euro at the current rate. Gamesa Solar (Spain), Nimrod Industries (Israel), Sole S.A., as well as Intersolar (Greece) and Schüco (Ger many) provided no data on turnover and on the num-ber of employees. Source: Manufacturer’s instructions

Table 1: Price comparison of thermosiphon systems. This type of solar unit is cheapest in China. But prices are under pressure everywhere due to the rising costs of raw materials. Almost all of the surveyed companies raised their prices in 2005; the Turkish companies were the most strongly aff ected, with an increase of up to 20 %. The majority of the respon-dents expect a similar trend for the coming year. However, in the medium term, prices should fall, with almost all companies expecting lower prices in fi ve years’ time. Only Solahart is more cautious in its forecast and expects a stable price level.

Source: Manufacturer’s instructions

Table 1: Price comparison of thermosiphon systems.

Manufacturer End customer price [€]

Collector area [m2] / Tank size [l]

Intersolar, Greece 2,500 4 / 200

Gasokol, Austria 2,480 4.5 / 300

Sunmaster, Austria 1,532 2.1 / 150

Tuma, Brazil 1,300 6 / 600

Solar Construct, Uganda

1,000 n/a

Dimas, Greece 750 2.9 / 200

Istek, Turkey 650 n/a

Titansol, Greece 600 n/a

Enalter, Brazil 520 2 / 200

Jiangsu Sunrain Solar Water Heater, China

150 n/a

Rest of the world: 119Rest of Asia: 370

USA/Canada: 91

Germany:525

Greece: 151Austria: 128

Rest ofEurope: 317

Turkey: 336

Israel: 266

Japan: 186South America: 224

Australia: 154Africa: 98

China: 8,750

Fig. 3: Installed solar collector capacity in 2004 – calculated from the cited areas using the conversion factor of 0.7 kW/m2. Most collectors are in-stalled in systems which op-erate on the gravity principle. Pumped systems are in the majority only in Central and Northern Europe. In the USA, a developing country in solar thermal terms, the majority of the systems installed to date are uncovered solar ab-sorbers for swimming pools. Total capacity: 11,715 MWth. Source: Sustainability Study,

Solarenergie 2005, Sarasin Bank



tem with the typical horizontal tank takes up 15 % of the production. Pumped systems and vacuum tubes play a subordinate role, with 6 % respectively. The com-pany produces absorbers which are coated either with Solarlack or by a selective method. »Sales of selective absorbers are growing rapidly«, says the Managing Di-rector Kemal Eraslan. »Vacuum systems are growing as well.« Eraslan has ambitious plans: »We have invested almost 2 million € in state-of-the-art machinery, be-cause in a few years we aim to become the biggest so-lar thermal company in Europe.« The company produces about 40,000 complete sets of solar water heaters each year. »We are able to manufacture a collector in one minute. We think that we have one of the fastest process flows in the world«, adds the managing director.

Global potential

As in Turkey, the world’s biggest thermal market China is also dominated by atmospheric open-loop systems (see box on page 40). These inexpensive units are also the standard in Brazil. With a total installed collector ar-ea of 320,000 m2 (224 MW) in all of South America (2004), the market here still holds plenty of potential. Things don‘t look much better in the domestic market of the »grand old lady« of the solar thermal sector. Solahart has been producing solar collectors in Aus-tralia since 1953 and holds a market share of 55 % in this country. But with a total of some 220,000 m2 (154 MW), the market of this entire sun-blessed continent is not much bigger than that of the small Alpine republic of Austria. Tab. 3 sets out the national market shares and the year of entry into the solar thermal market of the cited companies.

The main reason why the Australian company takes pole position in Fig. 1 is because it is represented in 80 countries all over the world. Brian Morris (Interna-tional Manager at Solahart) identifies a gradual global trend to closed-loop systems. But at the moment: »All of our competitors mainly produce the open-loop sys-tem which is cheaper and easier to build.« Solahart pro-duces about 30,000 units with Solarlack (half of which are closed-loop and half of which are open-loop) and about 20,000 with black chrome absorbers, 100 % of which are closed-loop.

Besides the technical standards, another aspect also plays a major role: »Design is very important, as one of the biggest barriers to overcome is the look of the sys-tem on people's roof tops«, comments Morris. This is why the company tries to keep the tank as low as pos-sible and supplies coloured systems which are coordi-nated with the design of the roof. Aesthetics also play a decisive role for Hasan Hüseyin Dag (Managing Director of Dagsan, Turkey): »Don‘t let your roofs get changed into a scrapyard«, is his clear motto.

A Central European market?

In Central and Northern Europe almost no simple gravi-ty solar systems have been installed so far. Sunset, one of the oldest solar suppliers in Germany, now aims to change this. The company recently brought the Sun-

The Managing Director of Gasokol, Robert Buchinger (left), presents the new thermo-siphon system. Photo: Gasokol

Army houses in Turkey: Ezinc installed 128 thermosiphon systems with a 200 litre tank each. Photo: Ezinc

Solar unit of a hotel in La Paz, Bolivia



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Sun & Wind Energy 1/2006 35

Vacuum tubes are dominant in China.Photo: Jiangsu Sunrain Solar Water Heater

Typical installation in BrazilPhoto: Tuma

Hotel unit in SicilyPhotos (2): Solahart

Gravity system for Germany. The tank is located inside in the attic.Figure: Sunset

Eraslan’s top-selling product: the Sunlight system with ver-tical tank Photo: Eraslan



silver system onto the market, manufactured by its Israeli joint-venture partner Chromagen.

In contrast to the systems in the sunny south, in the Sunset »solar unit for everyman« variant the

storage tank is not installed directly above the collec-tors in the open air. In chilly Germany this would lead to problems during strong frosty conditions. Instead the mechanic installs the tank under the roof, in the attic. This allows the collectors to be positioned lower on the roof and the water heated in them rises automatically to the water reservoir. The system can be used very eco-nomically and flexibly, especially when it is retrofitted in an existing heating system. The additional heating can be realised either by means of a continuous-flow water heater (electrically or gas operated) or conventi-onally by the burner via a heat exchanger in the tank. An already present hot water tank may also be used.

»Of course, it’s ideal if this can be incorporated in houses which have roof central heating«, explains Michael Fall (Sunset). In this case, it is important that the attic is insulated against frost. The solar loop is a closed loop in which a water-antifreeze mixture circu-lates and thus cannot freeze up. Sunset promises simple and fast installation – the installation components are pre-prepared.

1953 Solahart, Australia (55 %)1962 Chromagen, Israel (40 %)1970 Nimrod, Israel (25 %)1974 Sole, Greece (n/a)1975 Tuma, Brazil (10 %)1975 Sammler Solar, Greece (20 %)1976 Calpak, Greece (15 %)1979 Dimas Solar, Greece (20 %)1979 Solimpeks, Turkey (n/a)1979 Dagsan Solar, Turkey (n/a)1980 Enalter, Brazil (10 %)1980 Auraset Solar, Turkey (3 %)1982 Istek, Turkey (n/a)1984 Titansol, Greece (5 %)1984 Stibetherm, Greece (15 %)1985 Ezinc, Turkey (35 %)1988 Gasokol, Austria (n/a)1990 Nobel Xilinakis, Greece (n/a)1991 Intersolar, Greece (n/a)1994 Eraslan, Turkey (15 %)1995 Kodsan, Turkey (20 %)1998 Schüco, Germany (n/a)1998 Ao Sol, Portugal (40 %)1999 Jiangsu Sunrain, China (5 %)2001 Solar Construct, Uganda (70 %)2001 Sun Master, Austria (20 %)2001 Sunpower Solar, China (5 %)2001 Linuo Paradigma, China (3 %)2002 Kuzey Enerji, Turkey (5 %)2003 Solareks, Turkey (n/a)2005 Gamesa Solar, Spain (n/a)

Start of solar thermal business at the companies. Most of the Greek enterprises started out in the mid-1970s, with the Turkish companies following suit from 1979 onwards. The share of the national solar thermal market is given in brackets. Apart from Sola-hart in Australia, Ao Sol in Portugal and Solar Con-struct in Uganda, none of the markets have a domi-nant market leader. Source: Manufacturer‘ s instructions

Manufacturer Country Type Year of launch

Collector dimension [m2]

Tank capacity [liter]

Tank insulation Electric heating element [kW]

Maximum pressure [bar]

Open or closed loop

Solarglas Absorber Number of installed systems

website

Solahart Australia 1982 4 300 20 – 60 mm PU 2 – 4 10 both + black painted / black chrome

1,000,000 www.solahart.com

Gasokol Austria Save sol 300/2 2005 4.5 300 50 optional 3 closed + high selective n/a www.gasokol.com

Sun Master Austria 2006 2.1 / 4.2 150 / 300 50 mm rockwool optional 3 1 closed + high selective n/a www.sun-master.at

Enalter Brazil Simsol 2.0 V 2003 2 200 25 mm PU 3 0.4 open – black painted 60,000 www.enalter.com.br

Tuma Brazil Solarem 1975 6 600 35 mm PU 2.5 0.4 closed – black painted 15,000 www.tuma.ind.br

Changzhou Sunpower Solar

China 2001 2.3 2 250 55 mm PU 1.5 6 closed + high selective 300,000 www.sunpower-solar.com

Jiangsu Sunrain Solar Water Heater

China 2004 1 – 6 2 80 – 400 50 – 60 mm 1.5 6 both + high selective 600,000 www.lygtyy.com

Linuo Paradigma China 2004 2.5 2 150 50 – – open + high selective n/a www.linuo-paradigma.com

Schüco Germany Schüco Thermosiphon System 150/300

2006 2.1 / 4.1 150 / 300 50 mm PU 3 – 6 (optional)

6 closed +(4 mm)

high selective n/a www.schueco.com

Calpak – Cicero Hellas S.A. Greece Giga NS 200/4 GS 2003 4 200 50 mm PU 3.5 10 closed + high selective 12,000 www.calpak.gr

Intersolar Greece S-200S 1995 1.5/ 2 / 2.5 / 4 120 / 160 / 200 / 300 50 mm PU 2 10 closed + black painted n/a www.intersolar.gr

Dimas SA Solar Greece 200 2004 2.9 200 60 mm PU 1 12 closed + high selective 3,500 www.dimas-solar.gr

Nobel Xilinakis Greece SWHGL60 1990 3 160 PU 4 10 closed + n/a 15,000 www.nobel.com.gr

Titansol Greece n/a 1.8 / 2 / 2.8 120 / 160 / 200 PU 4 1 closed + black chrome 5,000 www.titansol.gr

Sammler Solar Greece M160 1986 2.2 145 PU 2 / 4 12 closed + high selective > 2,000 www.sammler.gr

Stibetherm Greece Sol150L 1984 2.3 150 50 mm 4 13 closed plexiglas black painted > 40,000 www.stibetherm.gr

Sole Greece Eurostar 150 1996 2.5 150 50 mm PU 4 30 closed + high selective / black painted / black chrome

22,000 Eurostar-solar.com

Chromagen (Sunset) Israel Sunsilver 2005 4.7 / 5.5 200 / 300 PU 60 mm / PU 50 mm – 6 closed + black chrome n/a www.chromagen.biz

Nimrod Israel n/a 2.1 / 2.3 / 2.5 300 PU 2.5 / 3 12 both + black painted / black chrome

n/a www.nimrod-solar.co.il

Ao Sol Portugal Ao Sol 190 / Ao Sol 350 n/a 2.4 190 / 350 50 mm 2 7 closed n/a high selective > 1,000 www.aosol.pt

Gamesa Solar Spain 2006 2.1 / 4.2 160 / 300 50 mm PU 1.5 2 3 closed + high selective n/a www.gamesa.es

Auraset Solar Turkey n/a 1.7 / 2.1 90 – 300 50 mm PU 2 8 closed + black painted n/a www.auraset.com

Dagsan Solar Turkey Solarsystem 1979 2.5 4 150 / 300 40 mm yes 10 closed + high selective / black chrome

200,000 www.dagsan.com.tr

Eraslan Solar Energy Systems

Turkey Skylight 1998 2.4 / 4.8 180 80 mm PU 2 9 closed + black painted n/a www.eraslan.com.tr

Ezinc Metal Turkey 1985 2.3 / 4.6 / 6.9 85 / 170 / 300 50 mm PU 2 8 both + high selective / black painted / black chrome

40,000 www.ezincmetal.com

Istek Turkey 1982 1.8 / 2.4 160 – 1,000 PU n/a n/a both + high selective / black painted / black chrome

2,000 www.isteksolar.com.tr

Kodsan Turkey KS n/a 2 100 / 200 / 300 50 mm PU 2 10 both n/a n/a n/a www.kodsan.com.tr

Kuzey Enerji Turkey KS-24-160 2004 2.4 4 160 55 mm PU 2 8 open + high selective 6,400 www.kuzeysan.com

Solareks Turkey 2004 1.8 – 2.5 75 – 300 50 mm rockwool 2 8 both – black painted > 1,000 www.solareks.com

Solimpeks Turkey TER n/a 2.1 170 PU 2 10 closed + high selective 1,000 www.solimpeks.com

Solar Construct Uganda n/a 2001 2.2 170 / 300 / 1,000 n/a 1.2 / 3 / 6 / 9 8 both + black chrome n/a www.solarconstruct.com

1 closed circuit, 6 bar consumption circuit 2 vacuum tube collector 3 closed circuit, 13 bar consumption circuit



Manufacturer Country Type Year of launch

Collector dimension [m2]

Tank capacity [liter]

Tank insulation Electric heating element [kW]

Maximum pressure [bar]

Open or closed loop

Solarglas Absorber Number of installed systems

website

Solahart Australia 1982 4 300 20 – 60 mm PU 2 – 4 10 both + black painted / black chrome

1,000,000 www.solahart.com

Gasokol Austria Save sol 300/2 2005 4.5 300 50 optional 3 closed + high selective n/a www.gasokol.com

Sun Master Austria 2006 2.1 / 4.2 150 / 300 50 mm rockwool optional 3 1 closed + high selective n/a www.sun-master.at

Enalter Brazil Simsol 2.0 V 2003 2 200 25 mm PU 3 0.4 open – black painted 60,000 www.enalter.com.br

Tuma Brazil Solarem 1975 6 600 35 mm PU 2.5 0.4 closed – black painted 15,000 www.tuma.ind.br

Changzhou Sunpower Solar

China 2001 2.3 2 250 55 mm PU 1.5 6 closed + high selective 300,000 www.sunpower-solar.com

Jiangsu Sunrain Solar Water Heater

China 2004 1 – 6 2 80 – 400 50 – 60 mm 1.5 6 both + high selective 600,000 www.lygtyy.com

Linuo Paradigma China 2004 2.5 2 150 50 – – open + high selective n/a www.linuo-paradigma.com

Schüco Germany Schüco Thermosiphon System 150/300

2006 2.1 / 4.1 150 / 300 50 mm PU 3 – 6 (optional)

6 closed +(4 mm)

high selective n/a www.schueco.com

Calpak – Cicero Hellas S.A. Greece Giga NS 200/4 GS 2003 4 200 50 mm PU 3.5 10 closed + high selective 12,000 www.calpak.gr

Intersolar Greece S-200S 1995 1.5/ 2 / 2.5 / 4 120 / 160 / 200 / 300 50 mm PU 2 10 closed + black painted n/a www.intersolar.gr

Dimas SA Solar Greece 200 2004 2.9 200 60 mm PU 1 12 closed + high selective 3,500 www.dimas-solar.gr

Nobel Xilinakis Greece SWHGL60 1990 3 160 PU 4 10 closed + n/a 15,000 www.nobel.com.gr

Titansol Greece n/a 1.8 / 2 / 2.8 120 / 160 / 200 PU 4 1 closed + black chrome 5,000 www.titansol.gr

Sammler Solar Greece M160 1986 2.2 145 PU 2 / 4 12 closed + high selective > 2,000 www.sammler.gr

Stibetherm Greece Sol150L 1984 2.3 150 50 mm 4 13 closed plexiglas black painted > 40,000 www.stibetherm.gr

Sole Greece Eurostar 150 1996 2.5 150 50 mm PU 4 30 closed + high selective / black painted / black chrome

22,000 Eurostar-solar.com

Chromagen (Sunset) Israel Sunsilver 2005 4.7 / 5.5 200 / 300 PU 60 mm / PU 50 mm – 6 closed + black chrome n/a www.chromagen.biz

Nimrod Israel n/a 2.1 / 2.3 / 2.5 300 PU 2.5 / 3 12 both + black painted / black chrome

n/a www.nimrod-solar.co.il

Ao Sol Portugal Ao Sol 190 / Ao Sol 350 n/a 2.4 190 / 350 50 mm 2 7 closed n/a high selective > 1,000 www.aosol.pt

Gamesa Solar Spain 2006 2.1 / 4.2 160 / 300 50 mm PU 1.5 2 3 closed + high selective n/a www.gamesa.es

Auraset Solar Turkey n/a 1.7 / 2.1 90 – 300 50 mm PU 2 8 closed + black painted n/a www.auraset.com

Dagsan Solar Turkey Solarsystem 1979 2.5 4 150 / 300 40 mm yes 10 closed + high selective / black chrome

200,000 www.dagsan.com.tr

Eraslan Solar Energy Systems

Turkey Skylight 1998 2.4 / 4.8 180 80 mm PU 2 9 closed + black painted n/a www.eraslan.com.tr

Ezinc Metal Turkey 1985 2.3 / 4.6 / 6.9 85 / 170 / 300 50 mm PU 2 8 both + high selective / black painted / black chrome

40,000 www.ezincmetal.com

Istek Turkey 1982 1.8 / 2.4 160 – 1,000 PU n/a n/a both + high selective / black painted / black chrome

2,000 www.isteksolar.com.tr

Kodsan Turkey KS n/a 2 100 / 200 / 300 50 mm PU 2 10 both n/a n/a n/a www.kodsan.com.tr

Kuzey Enerji Turkey KS-24-160 2004 2.4 4 160 55 mm PU 2 8 open + high selective 6,400 www.kuzeysan.com

Solareks Turkey 2004 1.8 – 2.5 75 – 300 50 mm rockwool 2 8 both – black painted > 1,000 www.solareks.com

Solimpeks Turkey TER n/a 2.1 170 PU 2 10 closed + high selective 1,000 www.solimpeks.com

Solar Construct Uganda n/a 2001 2.2 170 / 300 / 1,000 n/a 1.2 / 3 / 6 / 9 8 both + black chrome n/a www.solarconstruct.com

Table 2: Technical details of the gravity systems. Informa-tion was requested for the top-selling product. However, many companies provided in-formation right across their product range.Source: Manufacturer’s instructions

4 fl at or vacuum tube collector



39

Focus on Spain

While Sunset is attempting to conquer the domestic market with the inexpensive »solar unit for everyman«, other Central European manufacturers have set their sights elsewhere. They are hoping to score with high-quality but also highly priced products in Southern Euro-pean regions (Tab. 2). »The interesting markets are the ones in Spain, Italy and Portugal. High-quality products are in demand there, and we want to serve the customer segment that is prepared to spend more on high-quality products«, explains Robert Buchinger (Managing Direc-tor of Gasokol, Dimbach). Peter Lietz (Sales Manager at Greenonetec) takes a similar view: »Quality will gain ac-

ceptance in Southern Europe as well.« The Austrian sec-tor leader among the European collector manufacturers has been producing thermosiphon systems since 2002 (described in S&WE 1/2004, page 28). However, at Green-onetec this technology plays only a subordinate role and thus has not undergone any further development since then. The product is not listed in Tab. 1 because as a pure OEM manufacturer, the company does not wish to reveal any details of customer specifi cations.

The Sunmaster product is brand new. »We have just sold the fi rst models,« says Maria Radner (responsible for sales at Sunmaster). The German collector manufacturer Schüco has also recently developed a thermosiphon unit with built-in return fl ow pipe in the collector. The build-ing facade company, which is active worldwide, aims to open up new markets in the south. In this case, the product developers need not only to invent the solar unit by themselves. »The development of the appropri-ate roof anchoring was very important as well,« reports Roland Sillmann (Solar Technology Manager at Schüco). This is because typical southern roof shingles have a pro-nounced profi le and are extremely diverse. For Schüco, it was an inevitable decision to produce only closed-loop systems: The company has no control over the water quality and the corresponding danger of corrosion.

Gamesa, the Spanish manufacturer of wind turbines, is a new player in the solar thermal sector. Some time ago the company had already started up a solar division with photovoltaic energy, and now collector production is a declared strategic target of the group. The focus here is on large-scale systems, but the Spanish company also provides a thermosiphon system for domestic purposes.

As with Schüco, the challenge for Gamesa Solar is now to win over manufacturers of heating systems. And this is a twofold objective: fi rstly for solar thermal ener-gy in gen eral and secondly for its own product. Com-pared with other Mediterranean countries, solar thermal energy in Spain has so far remained in the shadows. In 2004, no more than 93,000 m2 (equalling 65 MW) was installed1, which is roughly a tenth of the area of Germa-ny, for instance. But Adolfo Gonzalez (Product Manager at Gamesa) is convinced that the market will experience an upturn: »The deployment of domestic systems (solar thermal in general) is still low in Spain. You can be sure it will be very diff erent in the future, as the new Building Technical Code enforces the installation of solar systems in new constructions.«

Like the German and Austrian manufacturers, Game-sa, too, is putting the emphasis on a high-quality prod-uct. In this case, the solar loop of the closed-loop system operates without pressure. »An expansion vessel is not necessary because, after the system has been fi lled with the fl uid, the heat exchanger provides enough space for fl uid expansion«, explains Gonzalez. One can only hope that other rich countries, such as Italy and France, will follow suit and, like the people in many much poorer regions, start to utilise the most environment-friendly of all existing water heating techniques. ✹

Jens-Peter Meyer

1 All fi gures for installed collector areas from: Sustainability Study, Solar Power 2005, Sarasin Bank, Switzerland. The thermal capacity of the areas is calculated with a conversion factor of 0.7 kW/m2.

Thermosiphon systems at the glance

Schüco‘s new thermosiphon system fea-tures a closed loop. Photo: Schüco

Typical atmospheric system with two tanks. Photo: Eraslan Solar



Atmospheric systems: In regions where the water supply is not constantly assured, customers prefer systems with an atmo-spheric, i.e. non-pressurized, domestic wa-ter circuit. In these systems, a second stor-age tank containing cold water is installed above the hot water tank. This cold water storage tank contains a break pressure valve. When the user taps hot water, gravi-ty causes water to fl ow down and replen-ishes the solar system automatically. Atmo-spheric systems are available in open-loop and closed-loop confi gurations.

Closed-loop systems are divided by a heat exchanger in the tank (usually dou-ble-shelled) into a domestic water circuit and a solar circuit. These systems can work with a water-antifreeze mixture and are thus preferred in regions where the tem-perature sometimes falls below freezing point. Moreover, in regions with corrosive domestic water the solar loop is protected from the aggressive water.

Open-loop systems do not have a sepa-rate solar loop. The water for domestic use is heated directly in the collector. This is the cheapest of the available system types.

Thermosiphon systems are solar domestic water heating systems in which the solar loop is driven solely by the automatic ris-ing of the heated water from the collector into the hot water tank installed above it. They dispense with a solar pump and solar controller.

In thermosiphon systems, the storage tank is installed above the collector. Photo: Enalter

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