the thermal capacity of a room. For renovation, this provides a good alternative to new heavy walls, which would require additional struc- tural support (Hadorn, 2008).
In spite of the advances in PCM, concrete has certain advantages for thermal storage when a massive building design approach is used, as in many of the Mediterranean countries. In this approach, the concrete also serves as the structure of the building and is thus likely more cost effective than thermal storage without this added function.
For active solar heating and cooling, a number of different collector technologies and system approaches have been developed due to dif- ferent applications—including domestic hot water, heating, preheating and combined systems—and varying climatic conditions.
In some parts of the production process, such as selective coatings, large-scale industrial production levels have been attained. A number of different materials, including copper, aluminium and stainless steel, are applied and combined with different welding technologies to achieve a highly efficient heat-exchange process in the collector. The materi- als used for the cover glass are structured or flat, low-iron glass. The first antireflection coatings are coming onto the market on an industrial scale, leading to efficiency improvements of about 5%. In general, vacuum-tube collectors are well-suited for higher-temperature applications.The production of vacuum-tube collectors is currently dom- inated by the Chinese Dewar tubes, where a metallic heat exchanger is integrated to connect them with the conventional hot-water systems. In addition, some standard vacuum-tube collectors, with metallic heat absorbers, are on the market.
The largest exporters of solar water-heating systems are Australia, Greece and the USA.The majority of exports from Greece are to Cyprus and the near-Mediterranean area. France also sends a substantial number of systems to its overseas territories. The majority of US exports are to the Caribbean region. Australian companies export about 50% of production (mainly thermosyphon systems with external horizontal tanks) to most of the areas of the world that do not have hard-freeze conditions.
PV electricity generation is discussed under the areas of overall solar cell production, thin-film module production and polysilicon production. The development characteristic of the PV sector is much different than the traditional power sector, more closely resembling the semicon- ductor market, with annual growth rates between 40 to 50% and a high learning rate. Therefore, scientific and peer-reviewed papers can be several years behind the actual market developments due to the nature of statistical time delays and data consolidation. The only way to keep track of such a dynamic market is to use commercial market data. Global PV cell production2 reached more than 11.5 GW in 2009.
Solar cell production capacities mean the following: for wafer-silicon-based solar cells, only the cells; for thin films, the complete integrated module. Only those com- panies that actually produce the active circuit (solar cell) are counted; companies that purchase these circuits and then make modules are not counted.
Direct Solar Energy
Figure 3.11 plots the increase in production from 2000 through 2009, showing regional contributions (Jäger-Waldau, 2010a). The compound annual growth rate in production from 2003 to 2009 was more than 50%.
Annual PV Production [MW]
Rest of World United States China Europe Japan
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Figure 3.11 | Worldwide PV production from 2000 to 2009 (Jäger-Waldau, 2010b).
The announced production capacities—based on a survey of more than 300 companies worldwide—increased despite very difficult eco- nomic conditions in 2009 (Figure 3.12) (Jäger-Waldau, 2010b). Only published announcements from the respective companies, not third- party information, were used. April 2010 was the cut-off date for the information included. This method has the drawback that not all com- panies announce their capacity increases in advance; also, in times of financial tightening, announcements of scale-backs in expansion plans are often delayed to prevent upsetting financial markets.Therefore, the capacity figures provide a trend, but do not represent final numbers.
In 2008 and 2009, Chinese production capacity increased over- proportionally. In actual production, China surpassed all other countries,
Annual Production/Production Capacity [MW]
Figure 3.12 | Worldwide annual PV production in 2009 compared to the announced production capacities (Jäger-Waldau, 2010a).