Iycee Charles de Gaulle Summary Solar Energy 2 Essay Research Paper Presentation

Solar Energy 2 Essay Research Paper Presentation

Solar Energy 2 Essay, Research Paper

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SOLAR ENERGY. All life on Earth depends on energy from the Sun. Solar

energy is the beginning of energy for photosynthesis. It provides the heat

necessary for workss and animate beings to last. The heat from the Sun causes

H2O on the Earth & # 8217 ; s surface to vaporize and organize clouds that finally

supply fresh rainwater.

Solar energy is the consequence of thermonuclear merger reactions deep

within the Sun. These reactions produce so much energy that they keep the

surface temperature of the Sun at about 10,300B0F ( 5,700B0C ) . Even though


energy is the largest beginning of energy received by the Earth, its strength

at the Earth & # 8217 ; s surface is really really low due to the big distance between

the Earth and the Sun and the fact that the Earth & # 8217 ; s atmosphere absorbs and

spreads some of the radiation. Even on a clear twenty-four hours with the Sun straight

operating expense, the energy that reaches the Earth & # 8217 ; s surface is reduced about 30

per centum by the ambiance. When the Sun is near the skyline and the sky is

cloudiness, the solar energy at land degree can be negligible. It besides varies

from one point to another on the Earth & # 8217 ; s surface.

However, in the twentieth century, the Sun & # 8217 ; s energy has become an

progressively attractive beginning for little sums of direct power to run into

human needs. A figure of devices for roll uping solar energy and change overing

it into electricity have been developed, and solar energy is used in a

assortment of ways. Solar energy is used to heat houses, and in many states

specially designed solar ovens are used for cooking. The Sun besides supplies

energy to electric generators that provide power for conditions and

communications orbiters and for wireless and telecasting equipment.

Because the strength of the Sun & # 8217 ; s radiation at the surface of the

Earth is so low, aggregators designed to capture solar energy must be big.

In the sunniest parts of the Continental United States, for illustration, in order

for a aggregator to garner adequate energy to function one individual for one twenty-four hours, the

country of the aggregator & # 8217 ; s surface must be about 430 square pess ( 40 square

metres ) . The existent energy that can be used depends on the efficiency of the

aggregator and of the device that converts the radiation into useable energy.

Flat-plate aggregators. The most common flat-plate aggregators consist

of a dark metal home base, covered with one or two sheets of glass, that absorbs

heat. The heat is transferred to air or H2O, called bearer fluids, that

flows past the dorsum of the home base. This heat may be used straight or it may be

transferred to another medium. Flat-plate aggregators are used for place and

hot-water warming. Flat-plate aggregators typically heat bearer fluids to

temperatures runing from 150B0 to 200B0F ( 66B0 to 93B0C ) . The efficiency of such

aggregators varies from 20 to 80 per centum.

Concentrating aggregators. When higher temperatures are required, a

concentrating aggregator is used. These aggregators reflect and concentrate

sunshine from a broad country. One such device, called a solar furnace, was

installed in the Pyrenees in France and has several estates of mirrors focused

on a individual mark. The energy concentrated at the mark is 3,000 times that

received by any individual mirror, and the unit produces temperatures of up to

3,630B0F ( 2,000B0C ) . Another construction, the alleged & # 8220 ; power tower & # 8221 ; works near

Barstow, Calif. , generates 10,000 kW of electricity. Here, the furnace

Acts of the Apostless as a boiler and generates steam for a steam turbine-electric generator

power works.

In sophisticated concentrating aggregators such as the California

tower, each mirror is rotated by a heliostat that directs the Sun & # 8217 ; s beams from

the mirror to the mark. Positioning motors, thrusts, and accountants make

such systems expensive. Less dearly-won aggregators can bring forth temperatures lower

than those of more advanced concentrating aggregators but higher than those of

flat-plate aggregators. For illustration, parabolic reflectors that concentrate

sunshine on black pipes can bring forth unstable temperatures of approximately 400B0 to 550B0F

( 200B0 to 290B0C ) and can concentrate the solar energy up to 50 times its

original strength.

Small Stand-Alone DC System

The little stand-alone system is an first-class replacing for propane

or kerosene visible radiations in a distant cabin, a recreational vehicle or a boat. The

size of the photovoltaic ( PV ) array and battery will depend upon single

demands. The existent size methods are discussed elsewhere. The PV arra


charges the battery during daylight hours and the battery supplies power to

the tonss as needed. The charge regulator terminates the charging when the

battery reaches full charge. The burden centre may incorporate metres to supervise

system operation and fuses to protect wiring in the event of malfunction or

short circuit in the house.

PV & # 8211 ; Generator Combination

The PV & # 8211 ; Generator Combination system may be an economical

option to a big stand-alone PV system, because the PV array does non

hold to be sized big plenty for worst instance conditions conditions. A gasolene,

propane or Diesel generator combined with a battery courser can provide power

when the PV array falls abruptly. If the PV array is sized for norm

conditions, so during extended cloud-covered state of affairss or periods of increased

burden, the generator can be started. When batteries are low, the generator

will power the AC tonss in the house every bit good as a battery courser to assist

reload the batteries. If the PV array is sized much smaller than needed for

normal usage, the generator can power top out tonss such as making wash or

pumping H2O and at the same time run the battery courser to bear down the

battery bank. In add-on to leting for a smaller PV array, a back-up

bear downing system may besides let usage of a smaller battery bank. Generator and

battery bank size must be chosen carefully for dependable system operation. See

the system sizing subdivision for more inside informations on equipment pick.

Utility Intertie

The public-service corporation intertie system is besides used in a grid connected house.

Alternatively of hive awaying power in batteries, it is sold to the public-service corporation company. The

Utility Intertie System employs a particular type of inverter, which inverts DC

power from the PV array into low deformation AC, acceptable for purchase by

the local public-service corporation power company. Batteries are non required for storage. The

power is delivered through a kilowatt-hour ( kWh ) metre to the public-service corporation grid as

it is produced by the PV faculties. A 2nd kWh metre is used to mensurate the

power consumed by the tonss in the house. The user of this system will detect

no difference from any public-service corporation system, except lower public-service corporation measures or perchance

payments from the power company for extra electricity that is generated.

AC Photovoltaic Module Intertie

At last ordinary place proprietors can get down to cut down their dependance on

public-service corporation power for their electricity. This type of public-service corporation sellback system is

comprised of PV faculties with little inverters mounted on them. This allows the

end product of the inverter-module combinations to be connected straight to the AC

line. The public-service corporation may necessitate a 2nd metre and gulf. The installing

cost of this type of intertie system is much lower than that of a big

inverter system. A little system can be installed, and as fundss allow,

extra AC PV faculties can easy be added to the system.


Conservation plays an of import function in maintaining the cost of a

photovoltaic system down. The usage of energy efficient contraptions and illuming

every bit good as non-electric options wherever possible can do solar

electricity a cost competitory option to gasoline generators and in some

instances, public-service corporation power.

Cooking, Heating & A ; Cooling

Conventional electric

cookery, infinite warming and H2O warming

equipment usage a prohibitory sum of electricity. Electric ranges usage 1500

Watts or more per burner, so bottled propane or natural gas is a popular

alternate to electricity for cooking. A microwave oven has about the same

power draw, but since nutrient cooks more rapidly, the sum of kW hours

used may non be big. Propane and wood are better options for infinite

warming. Good inactive solar design and proper insularity can cut down the demand

for heat. Evaporative chilling is a more sensible burden, and in locations

with low humidness, the consequences are about as good. One asset for chilling & # 8211 ; the

largest sum of solar energy is normally available when the temperature is

the highest.


Lighting requires the most study since so many options exist in type,

size, electromotive force and arrangement. The type of illuming that is best for one system may non be right for another.

The first determination is whether your visible radiations will be run on low electromotive force

direct current ( DC ) or conventional 110 V jumping current ( AC ) . In a

little place, an RV, or a boat, low electromotive force DC lighting is normally the best. District of columbia

wiring tallies can be kept short leting the usage of reasonably little gage wire.

Since an inverter is non required, the system cost is lower. If an inverter

is portion of the system, the house will non be dark if the inverter fails if

the visible radiations are powered straight by the battery.

In add-on to conventional size medium base low electromotive force bulbs, the

user can take from a big choice of DC fluorescent visible radiations, which have 3

to 4 times the light end product per W of power used compared with incandescent

types. Halogen bulbs are 30 % more efficient and really seem about twice as

brilliantly as similar electrical power incandescent because of the spectrum of visible radiation they

green goods. Twelve and 24 volt replacing ballasts are available to change over AC

fluorescent visible radiations to DC.

In a really big installing or one with many visible radiations, the usage of an

inverter to provide AC power for conventional lighting is cost effectual. In a

big stand alone system with AC illuming, the user should hold a dorsum up

inverter or a few low electromotive force DC visible radiations in instance the primary inverter fails.

It is a good thought to hold a DC powered visible radiation in the room whrere the inverter

and batteries are in instance there is a job. AC light dimmers will non

map on AC power from inverters unless they have pure sine moving ridge end product.

Small fluorescent visible radiations may non turn on with some & # 8220 ; load demand start & # 8221 ; type



Gas powered soaking up iceboxs are a good pick in little

systems if bottled gas is available. Modern soaking up iceboxs consume

5 to 10 gallons of LP gas per month. If an electric icebox will be used

in a stand-alone system, it should be a high efficiency type. SunFrost

iceboxs use 300 to 400 watt hours of electricity per twenty-four hours while

conventional AC iceboxs use 3000 to 4000 W hours of electricity per

twenty-four hours at a 70 degree mean air temperature. The higher cost of good quality

DC iceboxs is made up many times over by nest eggs in the figure of solar

faculties and batteries required.

Major Appliances

Standard AC electric motors in rinsing machines, larger store

machinery and tools, & # 8220 ; swamp ice chests & # 8221 ; , pumps etc. ( normally 1/4 to 3/4

HP ) require a big inverter. Often, a 2000 W or larger inverter

will be required. These electric motors are sometimes difficult to get down on

inverter power, they consume comparatively big sums of electricity, and

they are really uneconomical compared to high-efficiency motors, which use 50 % to

75 % less electricity. A standard lavation machine uses between 300 and 500

watt-hours per burden. If the contraption is used more than a few hours per hebdomad, it is frequently cheaper to pay more for a high-efficiency contraption ( if one

exists ) , instead than do your electrical system larger to back up a

low-efficiency burden. For many belt-driven tonss ( washers, drill imperativeness, etc. ) , their standard electric motor can frequently be easy replaced with a

high-efficiency type. These motors are available in either AC or DC, and come

as separate units or as motor-replacement kits.

Vacuum cleaners normally consume 600 to 1000 Watts, depending on how

powerful they are, about twice what a washer uses, but most vacuity cleaners

will run on inverters larger than 1000 Watts because they have low rush


Small Appliances

Many little contraptions such as chainss, wassailers and hair driers consume

a really big sum of power when they are used but by their nature necessitate

really short or infrequent usage periods, so if the system inverter and batteries

are big plenty, they may be useable. Electronic equipment, like stereos,

telecastings, VCR & # 8217 ; s and computing machines have a reasonably little power draw. Many of

these are available in low electromotive force DC every bit good as conventional AC versions,

and in general, DC theoretical accounts use less power than their AC opposite numbers. A

portable stereo & # 8220 ; roar box & # 8221 ; that runs on 8 or 10 & # 8220 ; D-cell & # 8221 ; batteries will

normally work on 12 Vs DC. Some have a DC input, or you can link wires

from the battery contacts to the 12 V system. This should be done by

person experienced in electronics fix.

In the 1950s scientists puttering with semiconducting materials found that by

presenting little, circumstantially controlled sums of certain drosss called

dopants to the semiconducting material matrix, the denseness of free negatrons could be

shepherded and controlled. The dopants, similar plenty in construction and

valency to suit into the matrix, have one negatron more or less than the

semiconducting material ; for illustration, doping with P, which has five valency

negatrons, produces a ( negative ) n-type semiconducting material, with an excess

negatron which can be dislodged easy. Aluminum, B, In, and

Ga have merely three valency negatrons, and so a semiconducting material doped with them is ( positive ) p-type, and has holes & # 8221 ; where the missing negatrons ought to be. These holes behave merely like negatrons, except that they have an opposite, positive charge. ( Holes are theoretical, but so are negatrons, and either or both may or may non be, but we know for certain that if one exists, they both do, because we can & # 8217 ; t make something out of nil in the physical universe. ) It

is of import to understand that, although slackly bonded or excess bearers

exist in a substance, it is still impersonal electrically, because each atom & # 8217 ; s

negatrons are matched one for one by protons in the karyon.

The merriment begins when the two semiconducting material types are closely united

in a pn-junction, and the bearers are free to roll. Being of opposite20

charge, they move toward each other, and may traverse the junction, consuming

the part they came from, and reassigning their charge to their new part


This produces an electric field, called gradient, which rapidly ranges

equilibrium with the force of attractive force of extra bearers. This field

becomes a lasting portion of the device, a sort of incline that makes bearers

be given to skid across the junction when they get close.

When light work stoppages a Photovoltaic cell, atoms are bombarded with

photons, and give up negatrons. When an negatron gets lopped off an atom, it

foliages behind a hole, which has an equal and opposite charge. Both the

negatron, with its negative charge, and the hole, with its positive charge,

get down a random walk by and large down the gradient. If either bearer wanders

across the junction, the field and the nature of the semiconducting material stuff

discourage it from recrossing. A proportion of bearers which cross this

junction can be harvested by finishing a circuit from a grid on the cell & # 8217 ; s

surface to a aggregator on the backplane. In the cell, the light pumps & # 8221 ;

negatrons out one side of the cell, through the circuit, and back to the

other side, stimulating any electrical devices found along the manner.