DUAL AXIS SOLAR TRACKING SYSTEM MAJOR PROJECT Submitted to Rajiv Gandhi Proudyogiki Vishwavidyalaya Vishwavidyalaya Towards Towards Partial Fulfillment of the Degree of B!"#$%R %F #&G'&##R'&G (#le)tri)al * #le)troni)s #ngineering+
GUIDED BY Md. Firoz
SUBMITTED BY Ashish Vr!" Chho#$"$ S"h% D&"' K%!"r Rohi# P"(d) S*"&(i$ So('%s"r
ELECTRICAL + ELECTRONICS ENGINEERING DEPARTMENT INSTITUTE OF ENGINEERING + SCIENCE IPS ACADEMY INDORE ,-/01
ELECTRICAL + ELECTRONICS ENGINEERING DEPARTMENT INSTITUTE OF ENGINEERING + SCIENCE
IPS ACADEMY INDORE
CERTIFICATE ,e are -leased to )ertify that the major -roje)t entitled 2DUAL AXIS SOLAR TRACKING SYSTEM3 submitted by following is a))e-ted. Ashish Vr!" Chho#$"$ S"h% D&"' K%!"r Rohi# P"(d) S*"&(i$ So('%s"r
-4-4EX--4-4EX-/ -4-4EX-1 -4-4EX-/5 -4-4EX-16
INTERNAL EXAMINER
EXTERNAL EXAMINER
Date/
Date/
A7'(o*$d8!(# 't is our great -leasure to e0-ress our -rofound gratitude to our esteemed guide Md.Firoz1 ssistant Professor1 #le)tri)al and #le)troni)s #ngg. De-t.1 '#S 'PS )ademy 'ndore for their valuable ins-iration1 able guidan)e and untiring hel-1 whi)h enabled us to do this -roje)t. ,e are grateful to Mr. B. N. Ph"d'1 Professor and De-artment "ead of #le)tri)al and #le)troni)s #ngineering1 '#S 'PS )ademy 'ndore1 for his keenness towards this work and efforts -ut in1 and also for sharing his valuable time to our -roblems and -roviding useful solutions. t this jun)ture we also take this o--ortunity to e 0-ress our dee- gratitude to all the fa)ulties of #le)tri)al and #le)troni)s #ngineering De-artment1 for their a--re)iation and moral su--ort. ,e are also thankful to all our friends who hel-ed us dire)tly or indire)tly to bring the dissertation work to the -resent sha-e.
Date/
shish Verma !hhotelal Sahu Dee-ak 2umar Rohit Pandey Swa-nil Sonkusare
A9s#r"7# Solar energy is the most readily available energy available on earth. The energy of the sun is used sin)e an)ient times. ,ith fast growing environmental )on)erns over the )limate )hange risks asso)iated with -ower generation with non3renewable energy1 solar -ower has been the b est answer over the de)ades. "owever1 the out-ut -ower of the solar )ell -anel is highly affe)ted by the sunlight in)ident angle. By tra)king the dire)tion of solar -anel to the sun1 it )an always be -ointing at the o-timum angle to harvest the ma0imum solar energy throughout a day or a year. ,e -ro-osed a Dual a0is Solar Tra)king System in whi)h dual a0is solar -hotovoltai) -anel is )hara)teri4ed by the )a-ability to move in hori4ontal and verti)al dire)tions. The -ro-osed sun tra)king system will use 5 -hoto resistors1 whi)h will be mounted on the sides of the -hoto module. By these -hoto resistors the solar tra)king system will be)ome more sensitive and will allow determining a more a))urate lo)ation of the sun. This tra)king system will make the solar -hotovoltai) array more effi)ient by kee-ing the -anel6s fa)e -er-endi)ular to the sun and therefore e0tra)t ma0imum solar energy resulting into in)reased overall effi)ien)y.
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During the last few years the renewable energy sour)es like solar energy have gained mu)h im-ortan)e in all over the world. Different ty-es of renewable or green energy resour)es like hydro-ower1 wind -ower1 and biomass energy are )urrently being utili4ed for the su--ly of energy demand. mong the )onventional renewable energy sour)es1 solar energy is the most essential and -rereEuisite resour)e of sustainable energy H71 8I. Solar energy refers to the )onversion of the sun6s rays into useful forms of energy1 su)h as ele)tri)ity or heat. -hotovoltai) )ell1 )ommonly )alled a solar )ell or PV1 is the te)hnology used to )onvert solar energy dire)tly into ele)tri)al -ower. The -hysi)s of the PV )ell (solar )ell+ is very similar to the )lassi)al -3n jun)tion diode. Sunlight is )om-osed of -hotons or -arti)les of solar energy. Semi)ondu)tor materials within the PV )ell absorb sunlight whi)h kno)ks ele)trons from their atoms1 allowing ele)trons to flow through the material to -rodu)e ele)tri)ity H:1 5I. Be)ause of its )leanliness1 ubiEuity1 abundan)e1 and sustainability1 solar energy has be)ome well re)ogni4ed and widely utili4ed H9I. Different resear)hes estimate that )overing @.7;J of the land on earth with 7@J effi)ient solar )onversion systems would -rovide 8@ T, of -ower1 nearly twi)e the world6s )onsum-tion rate of fossil energy H;I. This -roves the -otential of solar energy whi)h in turn -oints out the ne)essity of tra)king me)hanism in solar systems. The tra)king me)hanism is an ele)trome)hani)al system that ensures solar radiation is always -er-endi)ular to the surfa)e of the -hotovoltai) )ells (solar )ells+ whi)h ma0imi4es energy harnessing H
H?I. But the earth follows a )om-le0 motion that )onsists of the daily motion and the annual motion. The daily motion )auses the sun to a--ear in the east to west dire)tion over the earth whereas the annual motion )auses the sun to tilt at a -arti)ular angle while moving along east to west dire)tion
[email protected] sun6s lo)ation in the sky relative to a lo)ation on the surfa)e of the earth )an be s-e)ified by two angles as shown in Figure 7.7. They are the solar altitude angle (C+ and the solar a4imuth angle (+. 4imuth angle is the angle between the sun6s -osition and the hori4ontal -lane of the earth6s surfa)e while ltitude angle s-e)ifies the angle between a verti)al -lane )ontaining the solar disk and a line running due south H77I.
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Solar tra)king is best a)hieved when the tilt angle of the solar tra)king systems is syn)hroni4ed with the seasonal )hanges of the sun6s altitude. n ideal tra)ker would allow the solar modules to -oint towards the sun1 )om-ensating for both )hanges in the altitude ang le of the sun (throughout the day+ and latitudinal offset of the sun (during seasonal )hanges+. So the ma0imum effi)ien)y of the solar -anel is not being used by single a0is tra)king system whereas double a0is tra)king would ensure a )osine effe)tiveness of one.
'n a)tive tra)king or )ontinuous tra)king1 the -osition of the sun in the sky during the day is )ontinuously determined by sensors. The sensors will trigger the motor or a)tuator to move the mounting system so that the solar -anels will always fa)e the sun throughout the day. 'f the sunlight is not -er-endi)ular to the tra)ker1 then there will be a differen)e in light intensity on one light sensor )om-ared to another. This differen)e )an be used to determine in whi)h dire)tion the tra)ker has to be tilted in order to be -er-endi)ular to the sun. This method of sun tra)king is reasonably a))urate e0)e-t on very )loudy days when it is hard for the sensors to determine the -osition of the sun in the sky H78I. Passive tra)ker1 unlike an a)tive tra)ker whi)h determines the -osition of the sun in the sky1 moves in res-onse to an imbalan)e in -ressure between two -oints at both ends of the tra)ker. The imbalan)e is )aused by solar heat )reating gas -ressure on a Llow boiling -oint )om-ressed gas fluid that is1 driven to one side or the otherM whi)h then moves the stru)ture. "owever1 this method of sun tra)king is not a))urate H7:175I. )hronologi)al tra)ker is a time3based tra)king system where the stru)ture is moved at a fi0ed rate throughout the day as well for different months. Thus the motor or a)tuator is )ontrolled to rotate at a slow average rate of one revolution -er day (79 -er hour+. This method of sun tra)king is more energy effi)ient H79I. To tra)k the sun6s movement a))urately dual a0is tra)king system is ne)essary. The a)tiveK)ontinuous tra)king system tra)ks the sun for light intensity variation with -re)ision. "en)e1 the -ower gain from this system is very high H7;I. But to a)hieve this -ower gain the system uses two different motors )ontinuously for two different a0es. Finally the motivation of the -roje)t was to design and im-lement a dual a0is solar tra)king system. sim-le energy effi)ient and rugged tra)king model is -ro-osed in this -roje)t in order to build a dual a0is solar tra)ker. To tra)k the sun6s daily motion1 that is1 from east to west dire)tion1 a -air of light sensors is used and to tra)k the seasonal motion of the sun real time )lo)k (RT!+ is used to )reate the a))urate a4imuth angle from some -redetermined -arameters. The light intensity is )om-ared by mi)ro)ontroller and it generates the suitable )ontrol signals to move the motors in -ro-er dire)tion. So a driver )ir)uit is used to in)rease the voltage and )urrent level for the o-eration of the motors. Two geared D! motors are used for rotating the solar module in two different a0es whi)h ensures tra)king the -oint of ma0imum light intensity.
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from the )entre of the #arth to the )entre of the sun as shown in Figure 8.7. The de)lination is ma0imum (8:.59@+ on the summerKwinter (in 'ndia 87 Oune and 88 De)ember+ The de)lination angle (+ varies seasonally due to the tilt of the #arth on its a0is of rotation and the rotation of the #arth around the sun. 'f the #arth were not tilted on its a0is of rotation1 the de)lination would always be @. "owever1 the #arth is tilted by 8:.59 and the de)lination angle varies -lus or minus this amount. %nly at the s-ring and fall eEuino0es is the de)lination angle eEua l to @ H7?I. @o%r A(8$ 0 The "our ngle is the angular distan)e that the earth has rotated in a day. 't is
eEual to 79 degrees multi-lied by the number of hours from lo)al solar noon. This is based on the nominal time1 85 hours1 reEuired for the earth to rotate on)e i.e. :;@ degrees. Solar hour angle is
4ero when sun is straight over head1 negative before noon1 and -ositive after noon (here noon means 78.@@ hour+ H7?I. So$"r A$#i#%d C 0 The solar altitude is the verti)al angle between the hori4ontal and the line
)onne)ting to the sun as shown in Figure 7.7. t sunsetKsunrise altitude is @ and is ?@ degrees when the sun is at the 4enith. The altitude relates to the latitude of the sit1 the de)lination angle and the hour angle H8@I
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So$"r Azi!%#h 0The a4imuth angle is the angle within the hori4ontal -lane measured from
true South or &orth. The a4imuth angle is measured )lo)kwise from the 4ero a4imuth H8@I.
,., I(so$"#io( 'nsolation is a measure of solar radiation energy re)eived on a given surfa)e area and re)orded during a given time. 't is also )alled solar irradiation and e0-ressed as hourly irradiation if re)orded during an hour1 daily irradiation if re)orded during a day1 for e0am-le. The unit re)ommended by the ,orld >eteorologi)al %rgani4ation is >OKm8 (mega joules -er sEuare meter+ or OK)m8 (joules -er sEuare )entimeter+.Pra)titioners in the business of solar energy may use the unit ,hKm8 (watt3hours -er sEuare meter+. 'f this energy is divided by the re)ording time in hours1 it is then a density of -ower )alled irradian)e1 e0-ressed in ,Km 8 (watts -er sEuare meter+ H87I.
%ver the )ourse of a year the average solar radiation arriving at the to- of the #arthQs atmos-here at any -oint in time is roughly 7:;; watts -er sEuare meter. The SunQs rays are attenuated as they -ass through the atmos-here1 thus redu)ing the irradian)e at the #arthQs surfa)e to a--ro0imately 7@@@,Km8 for a surfa)e -er-endi)ular to the SunQs rays at sea level on a )lear day. The insolation of the sun )an also be e0-ressed in Suns1 where one Sun eEuals 7@@@ ,Km8
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,.> Pro?7#io( E::7# The insolation into a surfa)e is largest when the surfa)e dire)tly fa)es the Sun. s the angle in)reases between the dire)tion at a right angle to the surfa)e and the dire)tion of the rays of sunlight1 the insolation is redu)ed in -ro-ortion to )osine o f the angle as illustrated in Figure 8.:. This Q-roje)tion effe)tQ is the main reason why the Polar Regions are mu)h )older than eEuatorial regions on #arth. %n an annual average the -oles re)eive less insolation than does the eEuator1 be)ause at the -oles the #arthQs surfa)e are angled away from the Sun H8:I.
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,./ Pho#o;o$#"i7 Po*r Solar -anels are formed out of solar )ells that are )onne)ted in -arallel or series. ,hen )onne)ted in series1 there is an in)rease in the overall voltage1 )onne)ted in -arallel in)reases the overall )urrent. #a)h individual solar )ell is ty-i)ally made out of )rystalline sili)on1 although other ty-es su)h as ribbon and thin3film sili)one are gaining -o-ularity. Be)ause the PV )ells generate a )urrent1 )ellsK-anels )an be modeled as D! )urrent sour)es. The amount of )urrent a PV -anel -rodu)es has a dire)t )orrelation with the intensity of light the -anel is absorbing as illustration shown in Figure 8.5
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The normal to the )ell is -er-endi)ular to the )ell6s e0-osed fa)e. The sunlight )omes in and strikes the -anel at an angle. The angle of the sunlight to the normal is the angle of in)iden)e (+. ssuming the sunlight is staying at a )onstant intensity (+ the available sunlight to the solar )ell for -ower generation (,+ )an be )al)ulated as below/ , U )os(+
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"ere1 re-resents some limiting )onversion fa)tor in the design of the - anel be)ause they )annot )onvert 7@@J of the sunlight absorbed into ele)tri)al energy. By this )al)ulation1 the ma0imum -ower generated will be when the sunlight is hitting the PV )ell along its normal and no -ower will be generated when the sunlight is -er-endi)ular to the normal. ,ith a fi0ed solar -anel1 there is signifi)ant -ower lost during the day be)ause the -anel is not ke-t -er-endi)ular to the sun6s rays. tra)king system )an kee- the angle of in)iden)e within a )ertain margin and would be able to ma0imi4e the -ower generated H85I.
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-hotovoltai) )ell or -hotoele)tri) )ell is a semi)ondu)tor devi)e that )onverts light to ele)tri)al energy by -hotovoltai) effe)t. 'f the energy of -hoton of light is greater than the band ga- then the ele)tron is emitted and the flow of ele)trons )reates )urrent as shown in figure 8.9. "owever a -hotovoltai) )ell is different from a -hotodiode. 'n a -hotodiode light falls on n )hannel of the semi)ondu)tor jun)tion and gets )onverted into )urrent or voltage signal but a -hotovoltai) )ell is always forward biased .
