Energy Analysis on 300W SP Solar Photovoltaic (PV) Generator

Transcription

1 Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator KYAW WYN HUN - Ph.D Student (Mechanical Engineering), Yangon echnological Univerity, Yangon, Myanmar. lamin029@gmail.com Abtract: he main objective of thi paper i to gain inight into the energy achievement of 300W/12V SP photovoltaic generator with the whole year. he amount of photovoltaic energy achievement i baed on output power and unhine hour. he output power of PV i baed on olar inolation. o get the maximum output power, the PV panel mut be received the maximum olar inolation. When the PV panel i with the bet tilt angle, it will be received the maximum inolation. he other factor concerned with PV output power i cell temperature that i connected with ambient temperature. he location on analyi i nein ( latitude = º N, longitude = º E ), Yangon. Analyi reult are preented here and compared with experiment. Key Word: energy, SP photovoltaic, tilt angle, power, nein. 1. NRODUCON: Energy conumption i one of the indice in determining the level of development of a nation. herefore, availability of energy upply to all ector of life in any country i crucial for it development. All kind of energy, particularly electricity which i eriouly needed for economic development. Electricity from the un i ued in rural area to meet baic electricity need of a rural community. oday electricity upply in εyanmar i generated by fuel generator and hydroelectric power plant. However, far-flung area which are away from National Grid cannot enjoy the electricity generated by thee ource. Since Myanmar i a land of plentiful unhine, epecially in central and outhern region of the country, the olar energy could hopefully become the final olution to it energy upply problem. he direct converion of olar energy into electricity uing photovoltaic ytem ha been receiving intenive intallation not only in developed countrie but alo in developing countrie [1]. he power delivered by a PV ytem of one or more photovoltaic cell i dependent on the olar inolation, temperature, and the current drawn from the cell. 2. SOLAR ENERGY: Solar irradiance i a key driving force of the earth. t i alo ultimately the ource of all energy upplie except for nuclear energy. Hydroelectric, wind and wave energie are linked to climate, which i alo driven by the un through uneven heating on the earth. Direct converion of olar irradiance through olar energy ytem i obviouly linked to the un a well. Solar energy i available in abundance in mot part of the world. he amount of olar energy incident on the earth urface i approximately1.5 x kwh/year [2] Altitude Angle of he Sun at Solar Noon he angle formed between the plane of the equator and a line drawn from the center of the un to the center of the earth i called the olar declination,. t varie between the extreme of ±23.45º [3] in ( n - 81) 365 (1) where, = olar declination ( º ) n = day number Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 205

2 Having drawn the earth-un ytem a hown in Fig. 1 alo make it eay to determine a key olar angle, namely the altitude angle β N of the un at olar noon. he altitude angle i the angle between the un and the local horizon directly beneath the un [3] L (2) N β N = altitude angle (º) L = latitude of the ite (º) N Zenith L Equator N Local horizontal Fig. 1. he altitude angle of the un at olar noon [3] he tilt angle that would make the un ray perpendicular to the module at noon in Fig. 2 would therefore be: ilt = 90 β N PV module N ilt S Fig. 2. he tilt angle of the module [3] 2.2. Solar Poition at Any ime of Day he location of the un at any time of day can be decribed in term of it altitude angle β and it azimuth angle φ a hown in Fig. 3. By convention, the azimuth angle i poitive in the morning with the un in the eat and negative in the afternoon with the un in the wet. Notice that the azimuth angle hown in Fig. 3 ue true outh a it reference[3]. Noon Sunrie E Eat of S: φ > 0 φ Wet of S: φ < 0 Sunet Fig. 3. he un poition decribed by it altitude angle and it azimuth angle [3] W Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 206

3 he azimuth and altitude angle of the un depend on the latitude, day number and mot importantly, the time of day. he following two equation allow u to compute the altitude and azimuth angle of the un [3]. in co L co co H in L in (3) co in H in (4) co he difference between the local meridian (line of longitude) and the un meridian i the hour angle, with poitive value occurring in the morning before the un croe the local meridian. n the afternoon, the hour angle i negative. Conidering the earth to rotate 360º in 24 h, or 15º/h, the hour angle can be decribed a follow: 15 H (hour before olar noon) (5) hour = altitude angle of the un (º) φ = azimuth angle of the un (º) here i a light complication aociated with finding the azimuth angle of the un from Equation 4. During pring and ummer in the early morning and late afternoon, the magnitude of the un azimuth i liable to be more than 90º away from outh. Since the invere of a ine i ambiguou, in x = in (180 x), there i a tet to determine whether to conclude the azimuth i greater than or le than 90º away from outh. Such a tet i tan if co H, then φ 90º ; otherwie φ > 90º tan L 2.3. Direct-Beam Radiation he direct-beam radiation pae in a traight line through the atmophere to the receiver. he length of the path h 2 divided by the minimum poible path length h 1 i called the air ma ratio, m. A hown in Fig. 4, under the imple aumption of a flat earth the air ma ratio can be expreed a h 2 1 m (6) h in 1 m = air ma ratio h 2 h 1 Fig. 4. he length of the path taken by the un ray [3] he value of optical depth k and apparent extraterretrial flux A are a follow: 360 A in ( n ) 365 (7) 360 k in ( n -100 ) 365 (8) A = apparent extraterretrial flux (W/m 2 ) k = optical depth he direct-beam radiation B can be calculated by uing the equation hown below. Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 207

4 B = A e -km (9) B = direct-beam radiation (W/m 2 ) he tranlation of direct-beam radiation B (normal to the ray) into beam inolation triking a collector face BC i a imple function of the angle of incidence θ between a line drawn normal to the collector face and the incoming beam radiation hown in Fig. 5. t i given by co co co ( S - C ) in in co (10) BC = B co θ (11) BC = beam inolation triking on collector (W/m 2 ) θ = incidence angle φ c = collector azimuth angle Σ = tilt angle ncidence angle θ Σ S φ φ c Σ N Fig. 5. he collector and it aociated angle [3] 2.4. Diffue Radiation Diffue radiation ha been cattered by molecule and aerool in the atmophere. he component of the radiation coming from all direction in the ky i diffued. DH = C B (12) DH = diffue radiation on horizontal urface (W/m 2 ) C = ky diffue factor 360 C in ( n -100 ) 365 (13) he following expreion i ued to find the value of diffue radiation on the collector, 1 co 1 co DC DH C B (14) 2 2 DC = diffue radiation on the collector (W/m 2 ) t i common to conider eparately the direct (or beam) radiation coming from olar dik and the diffue radiation from elewhere in the ky with their um known a global radiation [2]. 3. PHOOVOLAC (PV) GENERAOR: An aement of the operation of olar cell and the deign of power ytem baed on olar cell mut be baed on the electrical characteritic, that i, the voltage-current relationhip of the cell under variou level of radiation and at variou cell temperature [4]. Fig. 6 i an equivalent circuit that can be ued for an individual cell, a module coniting of everal cell, or an array coniting of everal module. hi circuit require that five parameter be known: the light current L, Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 208

5 the diode revere aturation current o, the erie reitance R, the hunt reitance R h, and a curve fitting parameter a. At a fixed temperature and olar radiation, the -V characteritic of thi model i given by L L D o h (V R ) exp a V R 1 R h (15) L R D h R h V Fig 6. A equivalent circuit for PV generator he power i given by P = V (16) When the voltage, V i zero, hort circuit condition exit. he current at thi point i called hort circuit current, c. When the current, i zero; the voltage i at it maximum. hi voltage i called open circuit voltage, V oc. he voltage at the point where the power upplied reache it maximum i denoted a V mp and the current at thi point a mp. he manufacturer of PV module uually provide meaured value of V oc, c, V mp and mp at reference condition. he reference condition uually are at an incident olar radiation of 1000W/m 2 and an ambient temperature of 25ºC. With thee meaured value, the four parameter L, o, R and a can be evaluated. R h i aumed to be infinite and therefore the lat term in Equation 15 i neglected [5]. At hort-circuit condition, the diode current i very mall and the light current i equal to the hort circuit current : L = c (17) At open circuit condition, the load current,, i zero and the 1 in Equation 15 i mall compared to the exponential term o that V oc o L exp (18) a he erie reitance can be calculated from : mp a ln 1 Vmp Voc L R mp he PV module manufacturer alo provide the temperature coefficient for the hort circuit current, µ,c and the open circuit voltage, µ V,oc. With thee coefficient known, we can now decipher the value of the curve fitting parameter at reference condition. he relationhip i hown a: V,occ,ref Voc,ref N a ref (20),cc,ref 3 L,ref where; i the band gap energy (1.12 ev for ilicon and 1.35 ev for gallium arenide), N i the number of cell in the PV array, a ref i the curve fitting parameter at reference condition, c,ref i the cell temperature at reference condition, L,ref i the light current at reference condition, μ c i the temperature coefficient for the hort circuit current, μ Voc i the temperature coefficient for the open circuit voltage [5]. An increaing temperature lead to decreaed open circuit voltage and lightly increaed hort circuit current. n order for the model to reproduce thee effect, it i neceary to know how the model parameter o, L and a vary with temperature. he erie reitance R i aumed independent of temperature in thi model. ownend (1989) howed that the following equation are good approximation for many PV module [4]: (19) Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 209

6 a a L ref c c,ref G L,ref,c(c c, ref ) (22) G,ref 3 o c N c,ref exp 1 (23) o,ref c,ref a ref c where; G i the olar inolation (W/m 2 ), G ref i the olar inolation at reference condition (W/m 2 ), c i the PV cell temperature (ºC), oref i the diode revere aturation current at reference condition (A). An energy balance on a unit area of module which i cooled by loe to the urrounding can be written a G A G A UA ( ) (24) c a From Equation 24, G c a 1 (25) U From NOC (nominal operation cell temperature) condition 0325 U 0. K- m 2 /W, = 0.9 (Ued by all olar panel manufacturer). Subtituting thee value into Equation 25; c a G 1 (26) 0.9 Equation 26 how a relationhip between the cell temperature, c, the ambient temperature, a, the inolation level, G and the efficiency of the olar panel,. (21) 4. SPECFCAON DAA: he pecification data for 300 W/12V SP photovoltaic generator and the mean maximum average temperature data for nein, Yangon from Kaba Aye tation of Department of Meteorology and Hydrology are hown in able and. able 300W/12V SP Photovoltaic Specification Max: power at SC 300 W / 12 V Max: power voltage, V m 18.2 V Max: power current, m A Open circuit voltage, V oc 22.8 V Short circuit current, c 17.3 A Module efficiency ( % ) % No. olar cell 36 NOC temp: 46 ºC emp: coeff: of c A/K emp: coeff: of V oc V/K able Mean Maximum emperature Data for nein, Yangon Year JAN FEB MAR APR MAY JUN JUL AUG SEP OC NOV DEC Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 210

7 5. MEHODOLOGY: he way to find the tilt angle, olar inolation, voltage-current curve, output power and energy of photovoltaic generator are hown in the following flowchart. L,n Eqn: 1,2 Σ for month Eqn: 1-14 PV pecification, temperature Eqn: olar inolation Eqn: 1-14 the bet Σ -V curve, power, energy Fig 7. he flowchart of analyi 6. RESUL AND DSCUSSON: he olar inolation received from collector i changed with the tilt angle of the collector. he tilt angle i varied with day number, i.e. with month. he variou tilt angle with day number i hown in Fig. 8. n Fig.8, the tilt angle varied with month. hu, the tilt angle for January i the bet tilt angle for thi month. t may be the bet for other month, i.e. a year or may not be. tilt angle ( ) January February March April October September November December 5 Augut 0 May June July day number ( n ) Fig 8. he tilt angle of the collector with day number at olar noon For fixed axi olar ytem, the bet tilt angle i very important. At thi angle, the maximum inolation i achieved in a whole year. n Fig. 9, the total average inolation i changed with the tilt angle. According to the Fig. 9, the bet tilt angle i 17º. Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 211

8 total average iolation in a year ( W/m 2 ) tilt angle ( ) Fig 9. he tilt angle with total average inolation in a year at olar noon he olar inolation i varied with day number, i.e., with month. he olar inolation variation with month i hown in Fig March olar inolation ( W / m 2 ) February January April May June September Augut July October November December day number ( n ) Fig 10. he olar inolation with day number for tilt angle 17º at olar noon he current-voltage characteritic of a photovoltaic module i changing with ambient temperature and olar inolation. he following Fig. 11 and 12 how the current-voltage characteritic for one month and a year at olar noon. 20 January 15 current ( A ) voltage ( V ) Fig 11. he current and voltage characteritic of PV for January Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 212

9 current ( A ) JAN FEB MAR APR MAY JUN JUL AUG SEP OC NOV DEC voltage ( V ) Fig 12. he current and voltage characteritic of PV for a year he operating current and voltage can be get from current-voltage characteritic in Fig. 11. he power i achieved from thi operating current and voltage. he output power for 300W/12V photovoltaic generator i hown in Fig output power of 300W/12V PV month Fig 13. he output power of 300W/12V PV with month he energy achievement from PV i depended on unhine hour. he Fig. 14 how the energy achievement with unhine hour output energy of 300W/12V PV ( Wh ) unhine hour ( h ) JAN FEB MAR APR MAY JUN JUL AUG SEP OC NOV DEC Fig 14. he output energy of 300W/12V PV with unhine hour Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 213

10 7. Experiment Work he experiment i carried out in 28 July 2016 within 9 A.M to 3 P.M. he PV i connected with reitant box ( 1.5 Ω ) and then the current and voltage can be read with multi-meter. n thi way, the data are collected. hi data are depended on reitance of the reitant box. From thi data, the power can be calculated. he experiment etup (Σ=17,φ C = 0) i hown in Fig. 15. olar panel multi-meter reitant box multi-meter Fig 15. he chematic diagram of experiment etup he Fig.16 decribe the power output of 300W/12V PV on theory and experiment work. power output ( W ) theory experiment time ( hour ) Fig 16. he output power of 300W/12V PV with hour 8. CONCLUSONS: t i very important to find the bet tilt angle to get the maximum output power of PV in a fixed axi ytem. According to the reult, the bet tilt angle for PV generator i 17º for nein, Yangon. n thi location, the olar inolation i changing around 925 W/m 2 to 1075 W/m 2. he minimum output power i W found in June and the maximum power i W found in February. n the experiment work, the output power of PV i W at olar noon and W in theory. Everywhere away from National Grid can enjoy the electricity generated by olar energy REFERENCES: 1. het het Han Yee, Su Su Win, and Nyein Nyein Soe,: Solar Energy Potential and Application in Myanmar, Dr.P.Jayakumar,: Solar Energy: Reource Aement Handbook, September, Gilbert M. Mater, Stanford Univerity, ; Renewable and Efficient Electric Power Sytem. 4. John A. Duffie (Deceaed) and William A. Beckman, : Solar Engineering of hermal Procee, econd edition. 5. Mba E.F., Chukwuneke J.L., Achebe C.H., Okolie P.C.,: Modeling and Simulation of a Photovoltaic Powered Vapour Compreion Refrigeration Sytem. 6. Duffle, J.A., & Beckman, W.A. (1991). Solar Engineering of Solar Procee, John Wiley & Son, nc. 7. Ecktein, J. : Detailed Modeling of Photovoltaic Sytem Component, M.S. hei, Univerity of Wiconin Madion, (1990). Energy Analyi on 300W SP Solar Photovoltaic (PV) Generator Page 214