SOLAR ENERGYSolar energy, radiantlightandheatfrom thesun, is
harnessed using a range of ever-evolving technologies such assolar
heating,solar photovoltaics,solar thermal electricity,solar
architectureandartificial photosynthesis.[1][2]Solar technologies
are broadly characterized as eitherpassive solaroractive
solardepending on the way they capture, convert and distribute
solar energy. Active solar techniques include the use of
photovoltaic panels andsolar thermalcollectors to harness the
energy. Passive solar techniques include orienting a building to
the Sun, selecting materials with favorablethermal massor light
dispersing properties, and designing spaces thatnaturally circulate
air.In 2011, theInternational Energy Agencysaid that "the
development of affordable, inexhaustible and clean solar energy
technologies will have huge longer-term benefits. It will increase
countries energy security through reliance on an indigenous,
inexhaustible and mostly import-independent resource,
enhancesustainability, reduce pollution, lower the costs of
mitigatingclimate change, and keepfossil fuelprices lower than
otherwise. These advantages are global. Hence the additional costs
of the incentives for early deployment should be considered
learning investments; they must be wisely spent and need to be
widely shared".http://en.wikipedia.org/wiki/Solar_energy
SOLAR HEATINGAsolar thermal
collectorcollectsheatbyabsorbingsunlight. A collector is a device
for capturing solar radiation. Solar radiation is energy in the
form ofelectromagnetic radiationfrom theinfrared(long) to
theultraviolet(short) wavelengths. The quantity of solar energy
striking the Earth's surface averages about 1,000 watts per square
meter under clear skies, depending upon weather conditions,
location and orientation.The term "solar collector" commonly refers
tosolar hot water panels, but may refer to installations such
assolar parabolic troughsandsolar towers; or basic installations
such assolar air heaters.Solar powerplants usually use the more
complex collectors to generateelectricityby heating a fluid to
drive aturbineconnected to anelectrical generator. Simple
collectors are typically used in residential and commercial
buildings for space
heating.http://en.wikipedia.org/wiki/Solar_heating
SOLAR PHOTOVOLTAICSPhotovoltaics is the direct conversion of
light into electricity at the atomic level. Some materials exhibit
a property known as the photoelectric effect that causes them to
absorb photons of light and release electrons. When these free
electrons are captured, an electric current results that can be
used as electricity.The photoelectric effect was first noted by a
French physicist, Edmund Bequerel, in 1839, who found that certain
materials would produce small amounts of electric current when
exposed to light. In 1905, Albert Einstein described the nature of
light and the photoelectric effect on which photovoltaic technology
is based, for which he later won a Nobel prize in physics. The
first photovoltaic module was built by Bell Laboratories in 1954.
It was billed as a solar battery and was mostly just a curiosity as
it was too expensive to gain widespread use. In the 1960s, the
space industry began to make the first serious use of the
technology to provide power aboard spacecraft. Through the space
programs, the technology advanced, its reliability was established,
and the cost began to decline. During the energy crisis in the
1970s, photovoltaic technology gained recognition as a source of
power for non-space applications.
Solar cells convert sunlight directly into electricity. Solar
cells are often used to power calculators and watches. They are
made of semiconducting materials similar to those used in computer
chips. When sunlight is absorbed by these materials, the solar
energy knocks electrons loose from their atoms, allowing the
electrons to flow through the material to produce electricity. This
process of converting light (photons) to electricity (voltage) is
called the photovoltaic (PV) effect.Solar cells are typically
combined into modules that hold about 40 cells; a number of these
modules are mounted in PV arrays that can measure up to several
meters on a side. These flat-plate PV arrays can be mounted at a
fixed angle facing south, or they can be mounted on a tracking
device that follows the sun, allowing them to capture the most
sunlight over the course of a day. Several connected PV arrays can
provide enough power for a household; for large electric utility or
industrial applications, hundreds of arrays can be interconnected
to form a single, large PV system.Thin film solar cells use layers
of semiconductor materials only a few micrometers thick. Thin film
technology has made it possible for solar cells to now double as
rooftop shingles, roof tiles, building facades, or the glazing for
skylights or atria. The solar cell version of items such as
shingles offer the same protection and durability as ordinary
asphalt
shingles.http://science1.nasa.gov/science-news/science-at-nasa/2002/solarcells/http://www.renewableenergyworld.com/rea/tech/solar-energy/solarpv
SOLAR THERMAL ELECTRICITYMany power plants today use fossil
fuels as a heat source to boil water. The steam from the boiling
water rotates a large turbine, which activates a generator that
produces electricity. However, a new generation of power plants,
with concentrating solar power systems, uses the sun as a heat
source. There are three main types of concentrating solar power
systems:parabolic-trough,dish/engine, andpower
tower.Parabolic-trough systems concentrate the sun's energy through
long rectangular, curved (U-shaped) mirrors. The mirrors are tilted
toward the sun, focusing sunlight on a pipe that runs down the
center of the trough. This heats the oil flowing through the pipe.
The hot oil then is used to boil water in a conventional steam
generator to produce electricity.A dish/engine system uses a
mirrored dish (similar to a very large satellite dish). The
dish-shaped surface collects and concentrates the sun's heat onto a
receiver, which absorbs the heat and transfers it to fluid within
the engine. The heat causes the fluid to expand against a piston or
turbine to produce mechanical power. The mechanical power is then
used to run a generator or alternator to produce
electricity.http://www.renewableenergyworld.com/rea/tech/solar-energy/solarconcentrating
SOLAR ARCHITECTURESolar architectureis the integration ofsolar
paneltechnology with modern building techniques. The use of
flexible thin filmphotovoltaic modulesprovides fluid integration
with steelroofingprofiles that enhances the building's design.
Orienting a building to the Sun, selecting materials with favorable
thermal mass or light dispersing properties, and designing spaces
that naturally circulate air also constitute as solar
architecture.Initial development of solar architecture has been
limited by the rigidity and weight of standard solar power panels.
The continued development of photovoltaic (PV) thin film solar has
provided a lightweight yet robust vehicle to harnesssolar energyto
reduce a building's impact on the
environment.http://en.wikipedia.org/wiki/Solar_architecture
ARTIFICIAL PHOTOSYNTHESISArtificial photosynthesisis achemical
processthat replicates the natural process ofphotosynthesis, a
process that convertssunlight,water, andcarbon
dioxideintocarbohydratesandoxygen. The term is commonly used to
refer to any scheme for capturing and storing the energy from
sunlight in the chemical bonds of a fuel (asolar
fuel).Photocatalytic water splittingconverts water intoprotons(and
eventuallyhydrogen) and oxygen, and is a main research area in
artificial photosynthesis.Light-driven carbon dioxide reductionis
another studied process, replicating naturalcarbon
fixation.Research developed in this field encompasses design and
assembly of devices (and their components) for the direct
production of solar fuels,photoelectrochemistryand its application
in fuel cells, and engineering
ofenzymesandphotoautotrophicmicroorganismsfor
microbialbiofuelandbiohydrogenproduction from sunlight. Many, if
not most, of the artificial approaches are bio-inspired, i.e., they
rely
onbiomimetics.http://en.wikipedia.org/wiki/Artificial_photosynthesis
CONCENTRATED SOLAR POWERCompanies can choose between two types
of concentrated solar technology. Concentrated photovoltaics, or
CPV, uses mirrors or lenses to focus sunlight onto a small area of
solar cells, creating electricity. Concentrated solar power, or
CSP, on the other hand, uses mirrors to direct sunlight, or solar
thermal energy, onto a small receiver.CPVCPV uses parabolic
concentrators, reflectors or lenses to focus large amounts of light
onto a small photocell. An influx of more photons lets cells
generate more power. Reflective or mirrored surfaces can be
expensive, so design efforts have focused on finding inexpensive
reflective surfaces that can withstand environmental conditions
such as rain.CSPCSP is positioned to become a major source of
renewable electricity generation in the United States, according to
NREL. The largest CSP project in the world is under construction in
Arizona. Once completed, the 280-MW Solana facility will use
parabolic trough technology and thermal storage using molten salts.
Solana will use solar trackers with high-precision parabolic
mirrors that follow the suns path and concentrate its energy,
heating a fluid to more than 700F and using that heat to turn steam
turbines.There are four types of CSP technology, according
toNREL:Parabolic Trough Systems:Line- focus systems that use curved
mirrors to focus sunlight on a receiver.Linear Fresnel Reflector
Systems:Line-focus systems that use relaxed and flat mirrors
arranged to focus sunlight on a receiver.Power Tower
Systems:Point-focus systems that use heliostats to focus sunlight
on a tower-mounted receiver.Dish/Engine Systems:Point-focus systems
that use curved mirrors to focus sunlight on a receiver.The most
popular of these, parabolic trough solar technology, offers the
lowest cost solar electric option for large power plant
applications. A parabolic trough is a type of solar-thermal energy
collector. Sunlight is reflected by the mirror and concentrated on
the Dewar tube. One of the principle advantages of concentrated
solar thermal is that storage can be provided efficiently so
24-hour output can be provided, and output can be scheduled to meet
demand requirements.
http://www.solarpowerworldonline.com/2013/05/intro-to-concentrated-solar-power/CONCENTRATED
SOLAR GROWS IN THE USWith recent approval of Solar Reserves 200-MW,
two-towerSaguache Solar Energy Projectcomes a sense of excitement
for not onlySolar Reserve, but the industry as a whole. As Solana,
Ivanpah, Cresecent Dunes and Rice projects continue to be
constructed; this is the first announcement of a new CSP project,
showing that installed CSP capacity is increasing at steady rate in
2012.This is set to continue as more research has looked into a
CSP-PV mix to boost total output and smooth integration on the
grid. Under ideal conditions the delivery curve from PV does not
really match the demand curve for electricity: peak output tends to
happen around midday, whereas high demand in western countries can
extend well into the afternoon or even evening.This has become a
concern in places such as California, where the hope is that cheap
PV can significantly assist in meeting renewable energy and carbon
reduction targets.Currently, according to modelling done by Paul
Denholm and Mark Mehos of the US National Renewable Energy
Laboratory (NREL), at low levels of penetration (up to 10% of total
energy a year), PV displaces the highest-cost generation sources
and cuts the need for peaking capacity.However, they state: As the
amount of PV on the system increases, the need for operating
reserves also increases due to the uncertainty of the solar
resource, as well as its variability over multiple time scales.This
further emphasises CSPs value and importance of being able provide
dispatcahable power. As storage becomes more valued it is good news
for developers like Solar Reserve who develop plants that comprise
of storage technology making capacity more flexible and more
valuable.
http://www.solarpowerworldonline.com/2012/04/concentrated-solar-thermal-grows-in-u-s/
TRENDS AND CHALLENGES OF SOLAR THERMAL ENERGYSolar thermal
systems are a way to satisfy heating needs by capturing the thermal
energy of the sun for heating applications such as buildings, hot
water or swimming pools. Tremendous amounts of energy currently go
in to traditional heating applications that could be satisfied by
solar thermal power. In domestic situations, for example, heating
water accounts for approximately one-third of total energy use.
Using solar energy for domestic hot water could save significant
amounts of energy annually, meaning lower bills for homeowners and
fewer emissions from traditional hydrocarbon-based grid
power.Recent DevelopmentsDevelopments in solar thermal technology
have made these systems more reliable and more efficient and,
therefore, a more practical choice for prospective adopters.
Evacuated tube collectors can satisfy even large heating demands
and are used by customers seeking more sustainable and cost-saving
alternatives. Furthermore, off-grid sites can benefit from having
their own source of hot water from solar thermal power. New
technologies re-imagine solar thermal systems by incorporating
photovoltaic (PV) components. Example include PV thermal (PV/T)
systems that capture heat from a variety of sources including the
heat from PV modules and water heating that is powered directly by
PV-generated electricity.Emerging TrendsSolar thermal power faces
several challenges in the marketplace that currently stymie more
widespread adoption. Among these challenges is a shortage of
information and understanding among prospective customers regarding
the function and benefits of solar thermal systems. Also, the
initial cost of a solar thermal system is often considered too high
for consumers as a multitude of financing options, such as those
for PV, may not exist for thermal. Between these two major
obstacles, customers may be intimidated by solar thermal systems or
not quite understand the technology.Expected ChallengesThe onus is
on the solar industry as a whole and the professionals who work
within it to communicate the benefits of solar thermal power to
potential customers. As more people become aware of the features
and advantages of solar thermal technology and on-site heating
options, the demand for such systems will be much greater on all
scales. Solar thermal technology that is easier to use and can be
obtained at a lower cost to the customer will encourage more
widespread use. Reducing the points of failure or complexity of
solar thermal systems will make them more usable to the general
marketplace and will likely drive down overall cost in the
process.
http://www.solarpowerworldonline.com/2013/05/trends-and-challenges-of-solar-thermal-energy/
GAWA NI ELDRICHHISTORY of solar Energy
EARLY CIVILIZATIONSThe very first traceable use of the sun was
back in 7th century BC, when man used crystals to magnify the Sun's
rays for starting fires.
Around 300 BC, the Egyptians>used mirrors to reflect the
light from the Sun into their tombs to illuminate the way.>The
reflecting of the Sun's rays with mirrors was also used to light
torches.>They also used the sun to dry mummified bodies after
they had died,>built houses which trapped the Sun's heat,
allowing for lower day time and higher night time temperatures.>
It is believed that the Egyptians also used a form of passive solar
power to heat water.
In 20 AD ,Chinese>recorded using mirrors once again to light
torches for religious purposes.
100 and 400 AD , The Romans>began to build "bath houses" with
south facing windows between to let the Sun's warmth in.
around 600 AD by the Justinian Code>Sunrooms begin being
built on houses and public buildings, and become so popular that
"sun rights" are established by the Justinian Code around 600 AD to
ensure that all buildings have access to the sun.
Between 1000 AD and 1400 AD, Native Americans> built houses
on cliffs, positioned and designed to allow for trapping of heat
during the day and release at night.
INDUSTRIALthroughout the 18th and 19th century
>The very first recorded Solar Collector was made in 1767 by
Swiss inventorHorace de Soussare.>This is now known as
ahotboxand was used to test how much of the Sun's heat could be
trapped.>He made a rectangular box, which he insulated and
covered with glass. He placed two smaller boxes inside and put it
out in the Sun.>The bottom box heated to over 100 degrees C.
IMPORTANT PEOPLE IN THE CREATION OF THE MODERN SOLAR CELL
1839 -Alexandre Edmond Becquerelobserves thephotovoltaic
effectvia an electrode in a conductive solution exposed to light.
Thephotovoltaic effectis the creation of voltage or electric
current in a material upon exposure to light. >When the sunlight
or any other light is incident upon a material surface, the
electrons present in the valence band absorb energy and, being
excited, jump to the conduction band and become free. >These
highly excited, non-thermal electrons diffuse, and some reach a
junction where they are accelerated into a different material by a
built-in potential (Galvani potential). >This generates an
electromotive force, and thus some of the light energy is converted
into electric energy.
1887 -Heinrich Hertzinvestigates ultraviolet
lightphotoconductivityand discovers thephotoelectric
effectthephotoelectric effect, electrons are emitted from solids,
liquids or gases when they absorb energy from light. >Electrons
emitted in this manner may be calledphotoelectrons. *In the
photoelectric effect, by contrast, electrons are ejected from a
material's surface into vacuum, upon exposure to light. *The
photovoltaic effect differs in that the excited electrons pass
directly from one material to another, avoiding the difficult step
of passing through the vacuum in between.
1888-91 -Aleksandr Stoletovcreates thefirst solar cellbased on
theouter photoelectric effect Asolar cellakaphotovoltaic cell >
is an electrical device that converts the energy of light directly
into electricity by the photovoltaic effect. > It is a form
ofphotoelectriccell its electrical characteristicse.g. current,
voltage, or resistancevary when light is incident upon it > when
exposed to light, can generate and support an electric current
without being attached to any external voltage source.
**The operation of a photovoltaic (PV) cell requires 3 basic
attributes:
1 The absorption of light, generating either electron-hole pairs
or excitations. 2 The separation of charge carriers of opposite
types. 3 The separate extraction of those carriers to an external
circuit.
1905 -Albert Einsteinpublishes a paper explaining
thephotoelectric effecton a quantum basis. published a paper that
explained experimental data from the photoelectric effect as being
the result of light energy being carried in discrete quantized
packets. This discovery led to the quantum revolution. Einstein was
awarded the Nobel Prize in1921for "his discovery of the law of the
photoelectric effect"
http://www.solarpowerstore.co.za/articles/history-of-solar-energy.html
http://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Photovoltaic_effecthttp://en.wikipedia.org/wiki/Photoelectric_effecthttp://en.wikipedia.org/wiki/Timeline_of_solar_cells
GAWA NI FLORESSolar power is the conversion of sunlight into
electricity, either directly using photovoltaics (PV), or
indirectly using concentrated solar power (CSP). Concentrated solar
power systems use lenses or mirrors and tracking systems to focus a
large area of sunlight into a small beam. Photovoltaics convert
light into electric current using the photoelectric effect. Solar
Energy is the light and heat energy produced by the sun(radiant
energy).
Solar energy in vehicles-Some vehicles use solar panels for
auxiliary power, such as for air conditioning, to keep the interior
cool, thus reducing fuel consumption.Vehicles running purely or
mostly on Solar Energy are not sold as practical day-to-day
transportation devices at present, but are primarily demonstration
vehicles and engineering exercises, often sponsored by government
agencies. However, indirectly solar-charged vehicles are
widespread.Solar thermal Energy- is a technology for harnessing
solar energy for thermal energy.Low-temperature collectors are flat
plates generally used to heat swimming pools. Medium-temperature
collectors are also usually flat plates but are used for heating
water or air for residential and commercial use. High-temperature
collectors concentrate sunlight using mirrors or lenses and are
generally used for electric power production. STE is different from
and much more efficient than photovoltaics.cooking-Solar cookers
use sunlight for cooking, drying and pasteurization. They can be
grouped into three broad categories: box cookers-is an insulated
container with a transparent lid. panel cookers-use a reflective
panel to direct sunlight onto an insulated container reflector
cookers-uses various concentrating geometries (dish, trough,
Fresnel mirrors) to focus light on a cooking container.Electricity
productionConcentrating Solar Power (CSP)- CSP systems can absorb
sunlight and change it into heat that can be used to power a
steam-driven generatorphotovoltaic cell (PV)-PV systems change
sunlight directly into electricity.Both can be used to generate
utility-scale electricity in place of non-renewable energy sources
like fossil fuel(coal, natural gas and oil) or nuclear-fueled power
plant.
JOMS ADDITIONAL INFO
New TechnologiesBased on the photon-enhanced thermionic emission
(PETE) process, a new solar-energy device is about 100 times more
efficient than its previous design.Scientists working at the
Stanford Institute for Materials and Energy Sciences (SIMES) have
improved an innovative solar-energy device to be about 100 times
more efficient than its previous design in converting the suns
light and heat into electricity.The new device is based on the
photon-enhanced thermionic emission (PETE) process first
demonstrated in 2010 by a group led by Melosh and SIMES colleague
Zhi-Xun Shen, who is SLACs advisor for science and technology. In a
report last week in Nature Communications, the group described how
they improved the devices efficiency from a few hundredths of a
percent to nearly 2 percent, and said they expect to achieve at
least another 10-fold gain in the future.
http://scitechdaily.com/new-solar-energy-device-is-100-times-more-efficient-than-previous-design/
The international space station is powered by solar
energyTheelectrical system of the International Space Stationis a
critical resource for theInternational Space Station(ISS) because
it allows the crew to live comfortably, to safely operate the
station, and to perform scientific experiments. The ISS electrical
system usessolar cellsto directly convert sunlight toelectricity.
Large numbers of cells are assembled in arrays to produce high
power levels. This method of harnessingsolar poweris
calledphotovoltaics.The process of collecting sunlight, converting
it to electricity, and managing and distributing this electricity
builds up excess heat that can damage spacecraft equipment. This
heat must be eliminated for reliable operation of thespace
stationin orbit. The ISS power system usesradiatorsto dissipate the
heat away from the spacecraft. The radiators are shaded from
sunlight and aligned toward the cold void of deep
space.http://en.wikipedia.org/wiki/Electrical_system_of_the_International_Space_Station
