Solar heating

From Wikipedia, the free encyclopedia

Solar heating is the usage of solar energy to provide process, space or water heating. See also Solar thermal energy. The heating of water is covered in solar hot water. Solar heating design is divided into two groups:

  • Passive solar heating does not require electrical or mechanical equipment, and may rely on the design and structure of the house to collect, store and distribute heat throughout the building (passive solar building design).

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[edit] History

The very first solar heating factory in the world was built by Jewish immigrants, from South Africa, in Ashqelon Israel in 1952. In 1980 law was passed in Israel making solar heating mandatory.

[edit] How solar heating works

A household solar heating system consists of a solar panel (or solar collector) with a heat transfer fluid flowing through it to transport the heat energy collected to somewhere useful, usually a hot water tank or household radiators. The solar panel is located somewhere with good light levels throughout the day, often on the roof of the building. A pump pushes the heat transfer liquid (often just treated water) through the panel. The heat is thus taken from the panel and transferred to a storage cylinder.

[edit] Other uses

Solar heating also refers to the heating of any objects, including buildings, cars, through solar radiation. Solar heating depends on the solar radiation, surface area, surface reflectance, surface emissivity, ambient temperature, and thermal convection from wind. With most all objects on Earth, solar heating reaches a state of temperature equilibrium as the heat imparted by the sun is offset by the heat given off through reflection, radiation, and convection. White objects stay dramatically cooler than other objects because the most important variables are characteristics of the surface, reflectance, emissivity, convection and surface area. Silvery objects get hot even though they are excellent reflectors because they are very poor in heat emission. Human skin, and many other living surfaces, like tree leaves, have near perfect emissivity (~1.0), and so stay pretty cool. A perfect sunscreen is a dye that perfectly absorbs, with high emissivity, or perfectly reflects, ultraviolet and infrared while being transparent in visible light.

It is worth noting that it is impossible for any material to be a good absorber of a given frequency and at the same time a poor emitter of the same frequency ( or the other way around). The difference in absorption and emission arises because the radiation emitted by a relatively cold object like a human, has much lower frequency than the radiation emitted by a hot object like the sun. Materials which have high emissivity for low frequencies but high absorption at higher frequencies will therefore stay much cooler than materials which have high absorption of high frequencies and low emission of low frequencies.

[edit] Worldwide

Solar Hot Water Installed Capacity 2005[1]
Country million m2 GWth
China 79.3 55.5
EU 16.0 11.2
Turkey 8.1 5.7
Japan 7.2 5.0
Israel 4.7 3.3
Brazil 2.3 1.6
United States 2.3 1.6
Australia 1.7 1.2
India 1.5 1.1
World 125 88

[edit] Solar heating in Europe

Solar heating systems with glazed collectors* (kWth)[2]
Total (2006) Added in 2006 Added in 2005 Added in 2004
Germany 5 637 800 1 050 000 665 000 525 000
Greece 2 301 040 168 000 154 350 150 500
Austria 1 828 139 204 868 163 429 127 816
Italy 598 661 130 200 88 941 68 417
Spain 491 516 122 500 74 760 63 000
France 430 920 154 000 85 050 36 400
Cyprus 392 140 42 000 35 000 21 000
Switzerland 310 484 36 304 27 392 21 812
Denmark 253 596 17 710 14 875 14 000
Netherlands 222 909 10 280 14 174 18 410
UK 175 644 37 800 19 600 17 500
Sweden 165 850 19 977 15 835 14 041
Portugal 126 665 14 000 11 200 7 000
Poland 117 264 28 980 19 390 20 230
Slovenia 76 510 4 830 3 360 1 260
Czech Republic 74 711 15 421 10 885 8 575
Belgium 72 883 24 945 14 164 10 290
Slovakia 50 925 5 950 5 250 3 850
Romania 48 370 280 280 280
Bulgaria 17 570 1 540 1 400 1 260
Malta 16 702 3 150 2 800 2 951
Finland 11 545 2 380 1 668 1 141
Luxembourg 11 130 1 750 1 330 1 190
Ireland 11 053 3 500 2 450 1 400
Hungary 4 375 700 700 1 050
Latvia 2 695 840 700 350
Lithuania 1 925 420 350 350
Estonia 784 210 175 175
Total (GWth) 13.45 2.10 1.43 1.14
* The relation between collector area and capacity is 1 m2 = 0.7 kWthermal

[edit] See also

energy Portal

[edit] References

  1. ^ 2005: Record year for investments in renewable energy REN21: Renewables Global Status Report 2006 Update, 18.7.2006, p. 21.
  2. ^ Solar Thermal Markets in Europe, Trends and market statistics 2006 European Solar Thermal Industry Federation ESTIF, June 2007, p. 4.

[edit] External links