Solar Cooling

  • USA: Solar Heating and Vacuum Tube Collectors are catching up

    The US-American domestic solar heating and cooling market grew by 31 % in 2007, after the rapid climb of 77 % in 2006. These are figures from the annual statistics of the Energy Information Administration (EIA), which publishes the official energy statistics of the U.S. Government. In total 150,000...
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  • Lisbon: Solar cooling system for office complex

    Solar thermal installation on top of this huge banking complex in Lisbon: The Portuguese state bank Caixa Geral de Depositos (CGD) commissioned the Austrian engineering company S.O.L.I.D. to design the solar cooling plant. Photo: S.O.L.I.D.

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  • IEA Study "Solar Heat Worldwide": Global Market Growth of 22 % in 2006

    2006 was an extremely satisfying year for the global solar thermal industry. According to the new study “Solar Heat Worldwide. Markets and contribution to the Energy Supply 2006” on behalf of IEA Solar Heating & Cooling Programme the new installations grew 22 % in 2006. The authors from...

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  • What are solar thermal systems made of?

    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.

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  • What can solar thermal technology be used for?

    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.

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  • What are the long-term future perspectives of the sector in Europe?

    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/

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  • Is solar thermal technology still a niche market?

    There are a number of mature markets like Israel, Austria, Barbados, China or Cyprus where solar thermal is used by a wide majority of people for heating the domestic hot water and sometimes for room heating.

    One factor that shows the market penetration of this technology in a certain country is the total capacity installed per capita. In Cyprus there were 0.65 kWth in operation per capita at the end of 2007 followed by Israel (0.5 kWth/head), Austria (0.23 kWth/head) and Barbados (0.2 kWth/head). You find niche markets when looking at market penetrations such as in the United States with only 0.006 kWth per capita or in sunny South Africa with so far not more than 0.0036 kWth per capita. Also, there is still quite a large untouched potential worldwide in using solar thermal technology for cooling and for supplying process heat.

    Further information: Solar Heat Worldwide, a study from the IEA Solar Heating & Cooling Programme, May 2009 (http://www.aee-intec.at/0uploads/dateien648.pdf)

    0.7 kWth nominal solar thermal power equals 1 m2 of collector area.

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  • Renewable Energy Technology Roadmap up to 2020

    Published in January 2007, by EREC (European Renewable Energy Council), the document shows the ambitions of the European Renewable Energy Industry to reach the EU targets for 2020 for different sectors, including electricity, heating & cooling, and biofuels.
    It provides roadmaps for each sector, predicting its development and the conditions under which progress can be made.

    Nowadays, in the EU-25, fossil fuels contribute to almost 80 % of the primary energy demand. The target of 20% renewable energy use by 2020 seems to be quite challenging, especially if the appropriate legal framework and incentives are not put in place.

    This EREC report estimates that the contribution to the total primary energy demand will only be roughly 8% in 2010, slightly more than 12% in 2020 and only 12% in 2030 which is very far away from any target set. As for the energy supply, scenarios are more positive: 21% in 2020 if the policy developments and instruments continue progressing.

    If different and specific targets were set, then it would be easier to achieve the given targets. According to EREC, the Renewable Energy roadmap should consist of an overall target for 2020, followed by targets for the different sectors (electricity, heating/cooling, biofuels). Setting up individual targets for the different sectors would fasten the process, given that not all sectors are in the same stage of development.

    As what regards the solar thermal market, this report estimates that more funding on R&D would enable a broader adoption of solar thermal solutions for heating, cooling and storage.

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  • Heat Measurement Technologies for Larger Solar Thermal Systems

    This report provides an overview of the state of the art of measuring heat delivery in larger solar systems, looking also at the costs and accuracy of the measuring systems. The present document was produced within the framework of the Intelligent Energy- Europe project Key Issues for...

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