| Solar power is the technology of
| |
| | depths to generate power. These
|
| obtaining usable energy from the light of
| |
| | temperature differences are produced by
|
| the Sun. Solar energy has been used in
| |
| | sunlight.
|
| many traditional technologies for
| |
| | Fossil fuels are ultimately derived from
|
| centuries and has come into widespread
| |
| | solar energy captured by vegetation in
|
| use where other power supplies are
| |
| | the geological past.
|
| absent, such as in remote locations and
| |
| | In an indirect solar water heater the
|
| in space.
| |
| | fluid heated in the collector transfers
|
| Solar energy is currently used in a
| |
| | its heat through a heat exchanger to a
|
| number of applications:
| |
| | separate domestic water system.
|
| Heat (hot water, building heat, cooking)
| |
| | Sunlight reflected off a ceiling or other
|
| Electricity generation (photovoltaics,
| |
| | surface provides indirect lighting.
|
| heat engines)
| |
| | Passive or active
|
| Desalination of seawater.
| |
| | This distinction is made in the context
|
| Its application is spreading as the
| |
| | of building construction and building
|
| environmental costs and limited supply of
| |
| | services engineering.
|
| other power sources such as fossil fuels
| |
| | Passive solar systems use non-mechanical
|
| are realized.
| |
| | techniques of capturing, converting and
|
| Solar radiation reaches the Earth's upper
| |
| | distributing sunlight into useable
|
| atmosphere at a rate of 1366 watts per
| |
| | outputs such as heating, lighting or
|
| square meter (W/m2). The first map shows
| |
| | ventilation. These techniques include
|
| how the solar energy varies in different
| |
| | selecting materials with favorable
|
| latitudes.
| |
| | thermal properties, designing spaces that
|
| While traveling through the atmosphere 6%
| |
| | naturally circulate air and referencing
|
| of the incoming solar radiation
| |
| | the position of a building to the sun.
|
| (insolation) is reflected and 16% is
| |
| | Passive solar water heaters use a
|
| absorbed resulting in a peak irradiance
| |
| | thermosiphon to circulate fluid.
|
| at the equator of 1,020 W/m2. Average
| |
| | A Trombe wall circulates air by natural
|
| atmospheric conditions (clouds, dust,
| |
| | circulation and acts as a thermal mass
|
| pollutants) further reduce insolation by
| |
| | which absorbs heat during the day and
|
| 20% through reflection and 3% through
| |
| | radiates heat at night.
|
| absorption. Atmospheric conditions not
| |
| | Clerestory windows, light shelves,
|
| only reduce the quantity of insolation
| |
| | skylights and light tubes can be used
|
| reaching the earth's surface but also
| |
| | among other daylighting techniques to
|
| affect the quality of insolation by
| |
| | illuminate a building's interior.
|
| diffusing incoming light and altering its
| |
| | Passive solar water distillers may use
|
| spectrum.
| |
| | capillary action to pump water.
|
| The second map shows the average global
| |
| | Active solar systems use electrical and
|
| irradiance calculated from satellite data
| |
| | mechanical components such as
|
| collected from 1991 to 1993. For example,
| |
| | photovoltaic panels, pumps and fans to
|
| in North America the average insolation
| |
| | process sunlight into useable outputs.
|
| at ground level over an entire year
| |
| | Concentrating or non-concentrating
|
| (including nights and periods of cloudy
| |
| | Concentrating solar power (CSP) systems
|
| weather) lies between 125 and 375 W/m2 (3
| |
| | use lenses or mirrors and tracking
|
| to 9 kWh/m2/day).[4] This represents the
| |
| | systems to focus a large area of sunlight
|
| available power, and not the delivered
| |
| | into a small beam capable of producing
|
| power. At present, photovoltaic panels
| |
| | high temperatures and correspondingly
|
| typically convert about 15% of incident
| |
| | high thermodynamic efficiencies.
|
| sunlight into electricity; therefore, a
| |
| | Concentrating solar is generally
|
| solar panel in the contiguous United
| |
| | associated with solar thermal
|
| States on average delivers 19 to 56 W/m2
| |
| | applications but concentrating
|
| or .45 - 1.35 kWh/m2/day.
| |
| | photovoltaic (CPV) applications exist as
|
| The dark disks in the third map on the
| |
| | well and these technologies also exhibit
|
| right are an example of the land areas
| |
| | improved efficiencies. CSP systems
|
| that, if covered with 8% efficient solar
| |
| | require direct insolation to operate
|
| panels, would produce slightly more
| |
| | properly.
|
| energy in the form of electricity than
| |
| | Concentrating solar power systems vary in
|
| the total world primary energy supply in
| |
| | the way they track the sun and focus
|
| 2003.[6] While average insolation and
| |
| | light.
|
| power offer insight into solar power's
| |
| | Line focus/Single-axis
|
| potential on a regional scale, locally
| |
| | A solar trough consists of a linear
|
| relevant conditions are also important to
| |
| | parabolic reflector which concentrates
|
| the potential of a specific site.
| |
| | light on a receiver positioned along the
|
| After passing through the Earth's
| |
| | reflector's focal line. These systems use
|
| atmosphere, most of the sun's energy is
| |
| | single-axis tracking to follow the sun. A
|
| in the form of visible and Infrared
| |
| | working fluid (oil, water) flows through
|
| radiations. Plants use solar energy to
| |
| | the receiver and is heated up to 400 °C
|
| create chemical energy through
| |
| | before transferring its heat to a
|
| photosynthesis. Humans regularly use this
| |
| | distillation or power generation system.
|
| energy burning wood or fossil fuels, or
| |
| | Trough systems are the most developed CSP
|
| when simply eating the plants.
| |
| | technology. The Solar Electric Generating
|
| A recent concern is global dimming, an
| |
| | System (SEGS) plants in California and
|
| effect of pollution that is allowing less
| |
| | Plataforma Solar de Almería's SSPS-DCS
|
| sunlight to reach the Earth's surface. It
| |
| | plant in Spain are representatives of
|
| is intricately linked with pollution
| |
| | this technology.
|
| particles and global warming, and it is
| |
| | Point focus/Dual-axis
|
| mostly of concern for issues of global
| |
| | A power tower consists of an array of
|
| climate change, but is also of concern to
| |
| | flat reflectors (heliostats) which
|
| proponents of solar power because of the
| |
| | concentrate light on a central receiver
|
| existing and potential future decreases
| |
| | located on a tower. These systems use
|
| in available solar energy. The order of
| |
| | dual-axis tracking to follow the sun. A
|
| magnitude is about 4% less solar energy
| |
| | working fluid (air, water, molten salt)
|
| available at sea level over the timeframe
| |
| | flows through the receiver where it is
|
| 1961–90, mostly from increased
| |
| | heated up to 1000 °C before transferring
|
| reflection from clouds back into outer
| |
| | its heat to a power generation or energy
|
| space.
| |
| | storage system. Power towers are less
|
| Solar power technologies can be
| |
| | advanced than trough systems but they
|
| classified in a number of ways.
| |
| | offer higher efficiency and energy
|
| Direct or Indirect
| |
| | storage capability. The Solar Two in
|
| In general, direct solar power involves a
| |
| | Daggett, California and the Planta Solar
|
| single transformation of sunlight which
| |
| | 10 (PS10) in Sanlucar la Mayor, Spain are
|
| results in a useable form of energy.
| |
| | representatives of this technology.
|
| Sunlight hits a photovoltaic cell
| |
| | A parabolic dish or dish/engine system
|
| creating electricity.
| |
| | consists of a stand-alone parabolic
|
| Sunlight warms a thermal mass.
| |
| | reflector which concentrates light on a
|
| Sunlight strikes a solar sail on a space
| |
| | receiver positioned at the reflector's
|
| craft and is converted directly into a
| |
| | focal point. These systems use dual-axis
|
| force on the sail which causes motion of
| |
| | tracking to follow the sun. A working
|
| the craft.
| |
| | fluid (hydrogen, helium, air, water)
|
| Sunlight strikes a light mill and causes
| |
| | flows through the receiver where it is
|
| the vanes to rotate as mechanical energy,
| |
| | heated up to 1500 °C before transferring
|
| little practical application has yet been
| |
| | its heat to a sterling engine for power
|
| found for this effect.
| |
| | generation.[36][35] Parabolic dish
|
| In a direct solar water heater the water
| |
| | systems display the highest
|
| heated in the collector is used in the
| |
| | solar-to-electric efficiency among CSP
|
| domestic water system.
| |
| | technologies and their modular nature
|
| Sunlight which is not reflected provides
| |
| | offers scalability. The Stirling Energy
|
| direct lighting.
| |
| | Systems (SES) and Science Applications
|
| In general, indirect solar power involves
| |
| | International Corporation (SAIC) dishes
|
| multiple transformations of sunlight
| |
| | at UNLV and the Big Dish in Canberra,
|
| which result in a useable form of energy.
| |
| | Australia are representatives of this
|
| Vegetation uses photosynthesis to convert
| |
| | technology.
|
| solar energy to chemical energy. The
| |
| | Non-concentrating photovoltaic and solar
|
| resulting biomass may be burned directly
| |
| | thermal systems do not concentrate
|
| to produce heat and electricity or
| |
| | sunlight. While the maximum attainable
|
| processed into ethanol, methane, hydrogen
| |
| | temperatures (200 °C) and thermodynamic
|
| and other biofuels.
| |
| | efficiencies are lower, these systems
|
| Hydroelectric dams and wind turbines are
| |
| | offer simplicity of design a have the
|
| powered by solar energy through its
| |
| | ability to effectively utilize diffuse
|
| interaction with the Earth's atmosphere
| |
| | insolation. Flat-plate thermal and
|
| and the resulting weather phenomena.
| |
| | photovoltaic panels are representatives
|
| Ocean thermal energy production uses the
| |
| | of this technology.
|
| thermal gradients present across ocean
| |
| |
|
