| There are various technologies associated with solar | | | | heated by the heat absorbed in these plates. Passive |
| power, but all of them come under two major groups. | | | | solar heating like this uses the sun's thermal power to |
| The solar thermal technology--which includes passive | | | | heat the buildings. The south facing windows in the |
| solar heating and solar concentrator power systems-- | | | | northern hemisphere invite the sun's warm rays in, |
| use the sun to generate heat. Solar power technology, | | | | helped by building materials that absorb the sun's |
| the second group, converts solar radiation into | | | | thermal energy. |
| electricity through photovoltaics--a technology capable | | | | Another benefit of solar thermal technology, which isn't |
| of producing electricity when exposed to light. | | | | very apparent, and even seems oxymoronic, is its |
| Group 1: Solar Power Through Solar Thermal | | | | ability to cool buildings. This is done with |
| Technology Solar thermal technologies vary from | | | | absorption-cooling devices and desiccant cooling |
| small--in which a parabolic disk cooks food and boils | | | | systems. |
| water--to large, in which centralized solar power plants | | | | Group 2: Solar Power Through Photovoltaics |
| use many acres of mirrors to collect the sun's power, | | | | Photovoltaics is another way of collecting the sun's |
| focus it and heat water to steam that will power | | | | energy. Solar cells made of semi-conductors convert |
| generators. Solar concentrator power systems use | | | | the energy in sunlight into electricity. Sunlight, which is a |
| mirrors and lenses to concentrate sunlight onto a | | | | stream of energy particles known as photons, hits the |
| receiver, which converts the sunlight into heat. This | | | | semi-conductors and transfers its energy into them. |
| heat is used to heat fluid, which is led through pipes to | | | | These photons generate electricity as they hit the |
| a steam generator, where it is converted into | | | | silicon atoms in the solar cells. |
| electricity. | | | | Mirrored dishes and fresnel lenses, which consist of |
| Power plants with a capacity of 10 megawatts can | | | | concentric rings of segmental lenses, and are used to |
| power 10,000 households, and future power plants with | | | | help concentrate the sunlight onto a small area of |
| capacities ranging from 30 to 200 megawatts are | | | | photovoltaic cells. Concentrated photons cause a |
| possible. | | | | photoelectric effect as they hit one of the pairs of |
| Flat-plate solar collectors are large, flat boxes | | | | negatively charged plates and liberate the electrons. |
| dark-colored metal plates inside that absorb heat. This | | | | These liberated electrons are attracted to the other |
| system is great for providing heated water for | | | | negatively charged plate. This flowing of electrons |
| household use by passing water through pipes that are | | | | from one plate to the other is an electric current. |