A Control Strategy for Photovoltaic-Solid Polymer Electrolysis System Based on Surface Temperature of PV Panel

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1 Amrican Journal of Applid Scincs 5 (7): 5-, ISSN Scinc Publications Corrsponding Author: A Control Stratgy for Photovoltaic-Solid Polymr Elctrolysis Systm Basd on Surfac Tmpratur of PV Panl 1 Riza Muhida, 1 Wahyudi, Rifki Muhida, 3 Ahmad Unggul Priantoro 1 Dpartmnt of Mchatronics Enginring Dpartmnt of Scinc in Enginring 3 Dpartmnt of Elctrical and Computr Enginring Faculty of Enginring. Intrnational Islamic Univrsity Malaysia Jalan Gombak, 53, Kuala Lumpur, Malaysia Abstract: Procsss to produc hydrogn from solar photovoltaic powrd watr lctrolysis using solid polymr lctrolysis ar rportd. An altrnativ control of maximum powr point tracking mthod basd on analysis of PV panl s surfac Tmpratur for th PV-SPE systm was dsignd and implmntd. From this analysis an optimal voltag of PV can b obtaind and was ralizd as a rfrnc voltag of Dc-DC convrtr. By maintnanc th output voltag of PV using th rfrnc voltag control, th output PV can b optimizd at its MPP opration. Th MPPT prformanc and hydrogn production prformanc of this mthod hav bn valuatd and discussd basd on th rsults of th xprimnt. Kywords: Photovoltaic, hydrogn nrgy, Dc-dc convrtr, solid polymr lctrolysis (SPE) INTRODUCTION Photovoltaic hydrogn nrgy systm is on of th candidats for th nrgy altrnativs to solv th incrasing nvironmntal and nrgy problms. PVsolid polymr lctrolysis is on of th mthods to produc hydrogn from solar photovoltaic powrd watr lctrolysis. Solar photovoltaic powrd watr lctrolysis is highly possibl, sinc th solar nrgy and watr ar availabl on th larg scal. PV-hydrogn nrgy systm as on of mthod to rduc th global warming and substitut th ful of fossil cll. Thrfor, hydrogn producd by this systm can b usd to rplac th usag of oil and natural gas for transportation, hating and powr utilitis. Sinc th PV-hydrogn nrgy systm is xpnsiv to build, it should b opratd at thir maximum output powr lvls. Th PV output fluctuats with solar irradiation lvl, ambint tmpratur and load currnt, thn in dsigning th PV-SPE systm th ffct of ths thr factors must b Considrd [1]. In this study, an altrnativ control for maximum powr point tracking mthod applid to th PV-SPE systm is dsignd and is implmntd. An altrnativ control of maximum powr point tracking mthod basd on analysis of PV panl s surfac Tmpratur for th PV-SPE systm was dsignd and implmntd. From this analysis an optimal voltag of PV can b obtaind and was ralizd as a rfrnc voltag of Dc- DC convrtr. By maintnanc th output voltag of PV using th rfrnc voltag control, th output PV can b optimizd at its MPP opration. Th MPPT prformanc and hydrogn production prformanc of this mthod hav bn valuatd and discussd basd on th rsults of th xprimnt. SOLID POLYMER ELECTROLYSIS Th rsarch and dvlopmnt of solid polymr lctrolyt bgan whn Wright found ion conductivity in a PEO-alkalin mtal ion complx in 1975 [1]. Bcaus of th favorabl powr dnsity, Solid Polymr Elctrolysis is a candidat for high fficincy, pollution fr and othrs thir potntial applications in battris, ful clls, snsors and othr lctrochmical dvics. In this chaptr, th lctrical charactristics of Solid Polymr Elctrolysis and th ffcts of th its lctrical charactristics on th hydrogn production will b rportd. Riza Muhida, Dpartmnt of Mchatronics Enginring, Faculty of Enginring. Intrnational Islamic Univrsity Malaysia, Jalan Gombak, 53, Kuala Lumpur, Malaysia, Tl: , Fax:

2 Am. J. Applid Sci., 5 (7): 5-, SPE charactristics: SPE watr lctrolysis is on of th ways of producing hydrogn with comparativly high lvl of fficincy and compact quipmnt. Th SPE is composd of a mmbran, cathod and anod as shown in Fig. 1 [,3], and spcification of a unit cll prototyp of SPE for laboratory scal xprimnt dscribd in Tabl 1. Th SPE lctrolysis producs hydrogn by providing pur watr to on sid of polymr ion xchang film, which is put btwn anod and cathod. Th lctrochmical convrsions at th anod and cathod of SPE ar as follows: V 3*T 5*T*ln(T) *T o = η c as an xcss voltag at th cathod sid with th valu varying from.5 1 [V] at a cll currnt dnsity of 1[A/cm ]. η a is an xcss voltag at th anod sid with a maximum valu of.3[v] at cll currnt dnsity 1 [A/cm ]. R is th lctrical rsistanc of SPE and scrn and that mployd for th xprimnt has a valu of.37 [Ω]. I is th currnt that flows through th SPE. (3) + 1 H O H + O + + H + H (Cathod procss) (Anod procss) (1).5. SPE Voltag (V) Tmpratur of pur watr 9 o C Tmpratur of pur watr 6 o C Tmpratur of pur watr 3 o C Currnt (A) Fig. : V-I SPE Charactristics with fd watr tmpratur as paramtr. [] 4 Fig. 1: Diagram of Solid Polymr Elctrolysis Tabl 1: spcification of a unit cll prototyp of SPE for laboratory scal xprimnt Oprating Tmpratur Up to 9 [ o C] Wight of main part 1.7 [Kg] Effctiv ara 5 [cm ] Maximum lctrolyt 5 [A] currnt Elctrolytic voltag [V] Convrsion fficincy 6 [%] Gnratd H Tmpratur of pur watr 9 o C Tmpratur of pur watr 6 o C Tmpratur of pur watr 3 o C Currnt Cll (A) Fig. 3: Effct of currnt against th production rat of hydrogn. [] Th V-I quation of a SPE cll is givn by th following quation [3]. V = V + + IR () o c a + Whr V is SPE cll voltag, V o is th thortical dissociation voltag dpndnt on absolut tmpratur T [Klvin] as shown blow. [3] 6 Bcaus SPE producs hydrogn by xtracting watr as shown at Eq. (1), and th V-I output charactristics of SPE dpnds on watr tmpratur as shown in Eq. () and (3). Th xprimntal rsults illustratd in Fig., with chang th SPE cll tmpratur at 3, 6 and 9 o C w found th rlation btwn lctrolysis voltags was masurd at various currnts.

3 As shown in Fig. 3. Th rlation btwn th production rat of hydrogn was masurd at various currnt and undr th SPE cll tmpratur at 3, 6 and 9 o C. From th figur w can conclud that th production rat of hydrogn is proportional with th SPE currnt and th changing of th watr tmpratur of SPE not so changs th production rat of hydrogn. Effct of powr input against th production rat of hydrogn: As shown in Fig. 4. Th rlation btwn th production rat of hydrogn was masurd at various powr input and undr th SPE cll tmpratur from 3-6 o C. From th figur w can conclud that th production rat of hydrogn is proportional with th SPE powr input. Production rat of H 6 4 Tmpratur of pur watr 9 o C Tmpratur of pur watr 6 o C Tmpratur of pur watr 3 o C Powr Input (W) Fig. 4: Effct of powr input against th production rat of hydrogn [] PV-SPE MISMATCHING POINT Th systm dsignr aims to xtract th maximum achivabl lctrical powr output at all insolation lvls to nsur fficincy of th systm, spcially considring th high cost associatd with th PV panl and to ovrcom th mismatch btwn th PV panl and SPE. An important dsign considration is th match btwn th I-V charactristics of th PV panl and th SPE. If th SPE is connctd dirctly to th PV panl it impossibl to oprat on th MPP of PV panl du to th mismatch. Figur 5 shows a simplifid mismatch point btwn PV and SPE. Th masurd prformanc of PV and SPE at insolation. kw/m and surfac PV tmpratur of 3 o C and th tmpratur of SPE watr 6 o C, th SPE cll voltag rmain almost constant for all rang of voltags on th PV panl. Whn PV and SPE ar connctd dirctly th mismatch btwn th PV panl and SPE occurs, that is th oprating point Am. J. Applid Sci., 5 (7): 5-, 7 (point A) is at a lowr voltag than th maximum powr voltag (point P). This allows for voltag drops in th circuitry and th othr diminutions in prformanc as mismatch losss. This loss can b calculatd using th curv in Fig. 4. In this cas, oprating voltag will b.15 V and powr output will b 4 W against th maximum powr output of PV panl 7. W. Th loss of availabl PV powr output is 4 %. Voltag (V) PV Powr V-I Panl at. kw/m, 3 o C P max V-I SPE at Tmpratur Watr 6 o C Currnt (A) Fig.5: PV-SPE mismatching point As mntiond abov, without a matching point btwn PV panl and SPE cll, th systm fficincy can fall to an xtrmly low valu, which maks th systm unconomical. To ovrcom this two options ar availabl: Th first includ th carful slction of th SPE that matchs th maximum powr point of th PV panl as closly as possibl. In this situation th voltag of th SPE cll can b incoopratd into th PV panl. Howvr this maks th installation of this spcial SPE difficult. In othr obstacl, as indicatd in th prvious papr [4], is th mismatch btwn th ratd PV panl and actual powr, which prhaps rsult from th lowr insolation lvls and highr cll tmpratur. This is bcaus th nvironmntal changs caus th maximum powr point to fluctuat, making it difficult to obtain th matching valu btwn th actual MPPT of th PV panl powr and th SPE paramtrs. Du to this fluctuation it is of grat intrst to us th maximum powr-point tracking (MPPT), which is an lctronics control dvic that continuously matchs th output charactristic of th PV panl to th input charactristics of th SPE. As a rsult of this matching procss, th PV panl is forcd to dlivr maximum powr to th SPE at all tims. A Powr (W)

4 Am. J. Applid Sci., 5 (7): 5-, MPP USING REFERENCE VOLTAGE CONTROL TECHNIQUE Th prformanc of PV-SPE systm can b nhancd by tracking th maximum powr point of th PV panl and thn using a dc-dc convrtr to match th SPE voltag. During this procss, th stp down dc-dc convrtr is usd to driv a low voltag load from a high voltag PV panl. For this convrtr th output (SPE) voltag is always lowr than th input PV panl. Th powr flow from th PV panl to th SPE is controlld by mans of th on/off duty cycl of th switch. Th charactristic quation for th p-n junction subjct to insulation ar as follows: [5] { xp[ V / ] 1} J = J J (4) s o Whr J = currnt dnsity flowing into load. (A/m ) J s = short-circuit currnt dnsity. (A/m ) J o = dark (saturation) currnt dnsity (A/m ) = charg on lctron (1.6* -19 C) V = voltag across cll (V) k = Boltzmann s constant (1.3* -3 J/K) T = absolut tmpratur of dvic( o K) Th maximum voltag across th cll would b achivd undr opn-circuit condition, or J =, that is: V oc J s = ( )ln( + 1) Jo (5) If paramtrs of ach valu of and k ar substitutd in q. (9), thn q. (9) will b: 1 4 V = V 3.44 * T () mpp OC * From q. () w can find an optimal voltag of PV basd on valu of surfac tmpratur. And thn th optimal voltag was ralizd as a rfrnc voltag for DC-DC convrtr. Th prototyp aformntiond MPP tchniqu for PV-SPE Systm using rfrnc voltag controllr schma wr built and tstd. A modul of PV panl is usd in th systm and as load is a SPE cll, Fig. 6 shows schmatic diagram of this tchniqu. Fig. 6: Proposd total systm This mthod uss proportional intgrator controllr to control th duty factor of switch of puls-width modulator (PWM) DC-DC Convrtr. Whr V oc = opn circuit voltag of cll. Th output powr of th cll is: V P = JV = J J xp( ) (6) [ ] { }V s o 1 Th maximum powr point (MPP) is obtaind by taking th drivativ of P with rspct to V and stting th rsult qual to zro. This yild an implicit quation for th cll voltag at maximum powr: (7) V xp[ mpp Vmpp J ][1 + ] = 1+ J s o A dscription of th prototyp is as follows: a. A SPE plant with its spcification as shown in Tabl 1. b. A PV panl with its spcification as shown in Tabl. c. A proportional intgrator controllr consists of oprational amplifir, capacitor and variabl rsistor. d. Th comparator and sawtooth voltag gnrator us IC TL494 as th PWM controllr. From q. (5) and (7) w hav Tabl : Spcification of a PV panl usd in th Vmmp V () mmp V OC = ln( xp( )(1 )) + xprimnt at insolation AM 1 and tmpratur 5 o C. Using Maclaurin sris to rduc ths quations, thn Typ CP-4516 (Sanyo) w gt an approaching quation Opn circuit voltag (V OC ) 1 [V] 1 (9) Short circuit currnt (I SC ) 1. [A] Vmpp = VOC 4 Maximum powr 3 [W] Ara.4 [m ]

5 Th principal work of this controllr is that a rfrnc voltag (V rf ) was gnratd by tmpratur snsor (thrmocoupl) and oprational amplifir circuit. By us of PI controllr an rror voltag proportional to V rf V PV output is rsultd and thn this rror voltag is intgratd and transmittd to th comparator. Th transmittd signal is compard with sawtooth voltag. Thrfor th rsult of comparator signal is usd by IC TL 494 to produc a PWM signal to control th duty factor of switching frquncy to driv MOSFET. By varying th duty factor of th switch, I PV and V PV can b controlld. If th rror voltag is not zro, th signal to comparator will continuously incras and hnc th duty factor will chang in such a way to rduc th rror voltag to bcom zro. Sinc th voltag rfrnc always changs dpnding on th surfac tmpratur of PV as wll as th output voltag of PV which fluctuats with solar radiation. As th consqunc th controllr will continu to track to gt an qual valu btwn th voltag rfrnc and th output voltag of PV. (kw/m ) (Watt) (Watt) ( o C) (a) (b) (c) (d) () Tim (s) Am. J. Applid Sci., 5 (7): 5-, Insolation Powr for SPE Prod. Rat of Hydrogn Output Powr of PV PV's Surfac Tmpratur Fig. 7: Opration rsult of a prototyp PV-SPE systm RESULTS AND DISCUSSION Figur 7 shows a 13 minuts opration of th PV- SPE systm using MPP controllr. A data acquisition systm was usd to masur th input voltag and currnt, cll tmpratur, insolation and th production rat of hydrogn. Th xprimnt show that th powr of th PV panl can succssfully dlivrd th maximum powr to th SPE at all tims. Th comparison rsult of a xprimnt btwn using MPPT and without MPPT is illustratd in Fig.. W also did calculation to show numrical comparison as listd in Tabl 3. 9 (W) ( o C) (kw/m ) PV Powr Prod. rat of H Tmpratur Insolation Tim (s) Fig. : Comparison rsult btwn using convrtr and without convrtr Tabl 3: Comparison of th xprimntal rsult btwn using MPP and without MPP Itms Rsults Avrag Insolation.35 kw/m Avrag Surfac tmpratur of PV panl PV Powr using convrtr PV Powr without convrtr Advantag Powr using Convrtr Production Rat of H using convrtr Production rat of H without convrtr Advantag of Prod. of H using convrtr 35 o C 13.3 W 4. W 6% % Basd on Tabl 3 shows that using MPP tchniqu was succssful for incrasing mor th output of th production rat of hydrogn. CONCLUSION Sinc th PV-hydrogn nrgy systm is xpnsiv to build it should b opratd at th maximum output powr lvls. Howvr, th output of a PV gnrating systm is not systmically trackd and influncd by various factors such as solar insolation, solar cll's tmpratur and th connctd load condition (mismatching point). Thrfor, in dsigning th PV- SPE systm th ffct of ths thr factors should b considrd. Howvr, to ovrcom th advrs ffcts of systm and to oprat th PV panl at maximum powr point (MPP) vry instant, a MPPT is ssntial. Th production systm of hydrogn using th maximum powr Point Tracking basd on PV s surfac

6 Am. J. Applid Sci., 5 (7): 5-, tmpratur has bn proposd in this papr. Th main conclusions rachd in this study ar as follows: 1. Th proposd control mthods basd on th PV surfac tmpratur mthod for PV-SPE systm has bn ralizd and tstd.. Th maximum powr point tracking control schm was succssful for incrasing mor th output of th production rat of hydrogn. REFERENCES 1. Soltrmann O.E. and Da Silva E.P., 19. Comparativ study btwn th hysolar and a hypothtical intrnational projct in Brazil for hydrogn production and xportation (BHP) from photovoltaic nrgy and scondary hydrolctricity combind supply, Int. J. Hydrogn Enrgy 3 (9) (19) K. Torigo, Thrmolctric-hydrogn production systm for CO rcycl, Mastr Thsis, Osaka Univrsity, (In Japans). 3. H. Taknaka, 197. SPE lctrolysis tchnology: Charactristics and Applications, GS Nws Tchnical Rport, Japan Battry, Vol. 46, No. 1, Jun 197. (In Japans) 4. JHR Enslin and DB Snyman, 199. Simplifid fd-forward control of th maximum powr point in PV installations, IEEE IECON RECORD, San Digo, pp M.A Grn, 19. Solar Cll oprating principls, tchnology and systm application, prntic-hall Inc., Englwood Cliffs, NJ.

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