Solar thermal systems produce hot water whether the system is installed in Sweden, Germany, India, Tunisia or South America. The annual yield depends on the application (domestic hot water, pool heating, space heating), the local climatic conditions and system dimensioning (high or low solar fraction). The annual collector yield per square metre of collector area lies around 250 kWh/m2 for unglazed pool heating systems, 400 kWh/m2 for solar combi systems for hot water production and space heating in northern regions, and up to 700 kWh/m2 for installations in southern European regions used only for hot water preparation.
Flat plat collectors are made of metal, glass, insulating and joining materials. Typically copper, steel or aluminium is used for the absorber configuration. The sides and bottom of the collector are usually metal and insulated with mineral wool to minimize heat loss. The glass top is made of special glass to resist facture and maximise transmission of energy. In the future, a variety of materials and combinations of materials including plastics may be used to improve cost benefits ratios, higher temperature ranges and systems performance.
Vacuum tubes collectors are made of a borosilicate glass. Mostly the absorber layer is coated on the inner tube and no metal is required. But there are also tubes with an inner metal fin absorber.
For swimming pool heating, plastic or rubber are used to make low-temperature absorber plates.
The solar collector is usually mounted on the roof and is connected to a circuit containing water with propylene glycol anti-freeze added. The tank is also made of metal, partly stainless steel, partly enamelled steel or copper.
There is a wide variety of applications for solar thermal technology. The most common application is the heating of pool water, the heating of domestic hot water and space heating. Not very wide spread yet are solar cooling systems, because of the complexity of the technology and the high initial investment costs. Also, process heat applications such as in breweries or car washes, as well as in the food and textile industries, are still in their infancy. You can search for all these different kinds of applications in the filter section market sectors on the right hand side of the page.
What is the difference between vacuum tube collectors and flat plate collectors? With flat plate glazed collectors the absorbers are fitted in a box closed by a pane of glass (90 % market share in 2009 in Europe). Vacuum tube collectors – which are the dominating technology in China (96 % market share in 2008) – have the absorber coating on the outside of the inner tube in placed within an evacuated glass tube. Generally speaking, the advantage of vacuum tubes is a higher efficiency (less space required for the collector on the roof) and higher temperatures (necessary for process heat and some solar cooling technologies).
The disadvantage: The vacuum tubes produced in Europe are more expensive than the flat plate collectors but in some incentive schemes like in Germany they receive the same grants as the flat plate collectors. In China, some locally produced vacuum tube collectors have a poor quality performance, flat plate collectors are seen as high-quality products.
“Replacing imported fuels with local jobs”, this slogan of the European Solar Thermal Industry Federation (ESTIF) sums up perfectly the advantages of solar thermal technology for a national economy. The six biggest solar thermal markets in Europe – Germany, Austria, Italy, Spain, Greece and France – already exceeded 34,000 full time jobs in 2007 (check related article here). With an annual average growth rate of 20 % that is 6,800 jobs more each year. In the boom year 2008 in Europe this calculation results in 116,000 full-time jobs.
Furthermore solar thermal technology is an export trigger. In mature markets solar thermal industry is reaching high export rates. In 2007, Austria produced four times as many collectors as were newly installed in the country. In Greece, for the first time in 2008, the export will exceed local sales. Further Information: “Solar Thermal Action Plan for Europe” by the European Solar Thermal Industry Federation (ESTIF) http://www.estif.org/policies/st_action_plan/
The ambitious scenario of the European Solar Thermal Industry Federation (ESTIF) expects Europe will reach 0.7 kWth (1 m2 of collector area) per European in 2020, equivalent to a total capacity in operation in the EU by then of 320 GWth. To reach this target, a suitable support framework will be required and solar will then be widely used for both cooling and supplying process heat, though the majority of this capacity will still supply domestic hot water and space heating. The average yearly growth rate of the EU market necessary to reach this target is 31 % – less than the rate achieved in 2006 and only 7 % above the 2002 to 2006 average. This scenario requires – supposing a linear growth – an installation of 12.2 GWth (17 million m2) in the year 2020, six times more than in 2007, when 2.1 GWth (3 million m2) were newly installed in Europe as a whole. Further Information: “Solar Thermal Action Plan for Europe” by the European Solar Thermal Industry Federation (ESTIF) http://www.estif.org/policies/st_action_plan/
You have fast-growing independent producers here which focus on the production of solar thermal components only. Some of these companies are more than 30 years old, like the German Wagner & Co, the Israeli Chromagen and the US-American Sun-Earth. But the global market leaders today are newer firms like Greenonetec in Austria, the biggest flat-plate collector manufacturer in the world, which was founded in 1991 (turnover 2008: 117 million Euro). Find the ranking of the biggest flat-plate collector manufacturers here.
The giants of the European heating industry discovered the advantages of heating with the sun only ten years ago. Today all of them offer solar thermal systems and most of them have started producing their own collectors, e.g. Viessmann, Bosch Thermotechnik, the MTS Group or the Vaillant Group. Check the biggest European heating companies here.
The big players in China are the manufactures of the vacuum tubes for vacuum tube collectors; the three biggest among them are Linuo New Materials, Himin and Sangle.
Another sector which is gaining strength is the coatings industry, providing absorber sheets with a certain coating which guarantees very high absorptivity and very little emissivity. The two biggest players worldwide are the German companies Alanod-Solar GmbH & Co. KG and Bluetec GmbH & Co. KG. In the next few years, façade and roof specialists are likely to enter the market in Europe. Additionally, a few more national heating manufacturers will start selling and producing solar thermal systems.
Further information:www.greenonetec.com,www.sunearthinc, www.chromagen.biz, www.alanod-sunselect.de, www.bluetec-germany.de, http://www.bosch-thermotechnik.de/,www.vaillant-group.com ,www.viessmann.com,www.mtsgroup.com, www.wagner-solartechnik.de, www.lnxcl.com/ (Linuo New Materials), www.himin.com and www.sangle.com