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1 Availale online at SieneDiret Energy Proedia 74 (015 ) International Conerene on Tenologies and Materials or Renewale Energy, Environment and Sustainaility, TMREES15 Model Validation o an Emirial Potovoltai Termal (PV/T) Colletor. Ben eik el oine H 1, Touaek K 1, Kerrour F, Haloui H 1, Kelia A 1 1 nité de Reere Aliquée en Energies Renouvelales, RAER, Centre de Déveloement des Energies Renouvelales, CDER, 47133, Gardaïa, Algeria aoratory Modeling Renewale Energy Devies and Nanometri, Deartment o Eletroni, niversity Constantine 1, Constantine, 5000, Algeria Astrat Witin solar energy tenologies, te yrid otovoltai termal (PV/T) systems oer an attrative otion eause te asored solar radiation is onverted into termal and eletrial energy (te onversion an e done searately or simultaneously). In tis aer, an attemt is made to investigate te termal and eletrial erormane o a solar otovoltai termal olletor. A detailed termal model is develoed to alulate te termal arameters o a tyial PV/T olletor. Te termal arameters o tis olletor inlude solar ell temerature, outlet water temerature, termal eiieny and useul termal energy. Some orretions are done on eat loss oeiients in order to imrove te termal model o a PV/T olletor. A omuter simulation rogram is develoed in order to alulate te termal and eletrial arameters o a PV/T olletor. Te asorer is realized wit te galvanized iron o ig quality, allowing a good transer o eat wit lower ost omared to oer. Tis PVT as te advantage o its simle imlementation and its low ost omared to oter onigurations. Te results o numerial simulation are in good agreement wit te exerimental measurements noted in te revious literature. It is oserved tat te termal simulation results otained in tis aer is more reise tan te one given y te revious literature. It is also ound tat te termal eiieny o PV/T olletor is aout 54.51% in te mode o water eat exanger, and 16.4% in air eat extration, te eletrial eiieny is 11.1%, or a samle limati, oerating and design arameters. Pulised 015 Te y Elsevier Autors. td. Pulised Tis an y oen Elsevier aess td. artile under te CC BY-NC-ND liense Peer-review (tt://reativeommons.org/lienses/y-n-nd/4.0/). under resonsiility o te Euro-Mediterranean Institute or Sustainale Develoment (EMISD). Peer-review under resonsiility o te Euro-Mediterranean Institute or Sustainale Develoment (EMISD) Keywords: Hyrid solar system; solar otovoltai termal (PV/T) olletor; termal erormane, Perormane analysis, simulation Pulised y Elsevier td. Tis is an oen aess artile under te CC BY-NC-ND liense (tt://reativeommons.org/lienses/y-n-nd/4.0/). Peer-review under resonsiility o te Euro-Mediterranean Institute or Sustainale Develoment (EMISD) doi: /j.egyro

2 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) Introdution A otovoltai termal (PVT) system is a omination o otovoltai ells and a termal olletor. Su a olletor, wen exosed to sunligt, will rodue eletriity and termal energy. In su a system, te termal system omonent ats as a eat sink to te otovoltai ells, tus imroving its eiieny. Energy, tat is not asored y te PV ells, is utilized in te termal system, and ene, ot tese systems interdeendent. Te eat extrated rom te otovoltai termal system an e used or domesti water eating system or or sae eating [1]. Te yrid PVT systems an e lassiied aording to te used tye o working luid, ommonly PVT air eating systems (PVT/a) and PVT water eating systems (PVT/w). Some teoretial and exerimental researes on tese two tyes o yrid PVT systems ave een onduted in reent years. Hegazy [] evaluated te erormanes o our oular designs o PVT/a systems inluding te air lowing over te asorer or under it, and on ot sides o te asorer in single ass or doule ass mode, tis study rovided water signiiant inormation aout te design and oeration o su tyes o PVT systems. Tonui et al. [3, 4] imroved te erormane o PVT/a system y reasonale strutural modiiations to enane eat astration roess. By model analysis and exerimental veriiation, Tiwari et al. [5] evaluated te overall eiieny (eletrial and termal) erormane o a PVT/a system on limati onditions in India. Aterwards, Raman and Tiwari [6, 7] onduted urter analyses ased on energy and exergy or a doule-ass yrid PVT olletor on dierent limati onditions in India. Saraddi et al. [8, 9] evaluated te termal, eletrial and exergeti erormane o a tyial PVT/a system y a series o detailed energy and exergy analytial aroaes. Kumar et al. [10] erormed a omreensive steady state analysis to evaluate and omare te termal and eletrial erormane o a doule-ass PVT/a system wit and witout seii oniguration o vertial ins. Reently, Al-Alili et al. [11] roosed a yrid desiant assisted air onditioner system owered y PVT olletor. Te simulation and omutation results sowed su a roosed system ould meet te orresonding requirements o uildings in umid and ot limates. Comared wit oter solar air onditioners, te overall erormane o tis air onditioner system was imroved. Besides, Huang et al. [1] analyzed te erormane o an integrated PVT solar water eater wit a ommerial olyrystalline PV module. sing te onet o rimary-energy saving eiieny, te erormane o tis system was evaluated and measurements or erormane imrovements were mentioned. By develoing a series o steady and dynami simulation models, Zondag et al. [13, 14] onduted energy erormane analyses or a PVT/w sys-tem. Kalogirou et al. Kalogirou et al. [15] resented TRNSYS simulation results or a yrid PVT solar systems or domesti ot water aliations working wit eiter assive (termo-syon) or ative (um irulating) mode. Ji et al. [16] onstruted a lat-ox aluminum-alloy PVT/w system designed or natural irulation, onduted out-door tests and erormed dynami simulations on an imroved rototye in a moderate limate region. Cow et al. [17] exerimentally analyzed a aade-integrated PV/water-eating system; wit wi tremendous energy savings an e aieved. Suggestions on urter erormane imrovements o tis system were given onsequently. Roles- Oamo et al. [18] onstruted an exerimental model o a yrid PVT/w system wit te aliation o a seii iaial PV module or enaning eletri energy rodution and estimated te overall solar energy utilization eiieny o tis system. Erdil et al. [19] onstruted a yrid PVT domesti water re-eating system and made exerimental measurements or tis system in Cyrus. Te ay-ak eriod was estimated onsidering te required modiiation osts on PV module. It was onluded tis low-ost yrid system wit a relatively sort ay-ak eriod was eonomially attrative. Wit a teoretial model, Duey et al. [0] evaluate te termal, exergeti and eletrial erormane o PVT lat late water olletors y anging te numer o olletors onneted in series, alternative series/arallel omination modes and dierent weater onditions o India. Results sowed te lat late water olletors artially overed y PV module were eneiial or tose users wose riority requirements were ot water generation, and tose ully overed were eneiial or users wose riority requirements were eletriity generation. Wit numerial simulations, Santergen et al. [1] onstruted a one-overseet-and-tue PVT system or domesti ot water eating. Te meanisms determining te eletrial and termal yields we reanalyzed and imrovement measures were roosed in tis work. Pei et al. [] designed a detailed simulation model o a eatie PVT system, analyzed and omared te annual eletrial and termal erormane o su HP-PVT systems wit and wit-out auxiliary eating equiment in dierent limate onditions o Cina. A new aroa o a yrid otovoltai termal olletor (PVT) troug an exerimental study as een roosed y K. Touaek [3, 4, 7 and 8]. Tis novel olletor onstitutes a new tenial aroa to maximize te total outut o onversion wit lower ost omared to te traditional yrid olletors, it is araterized y a

3 109 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) galvanized steel asorer laed at te lower art o te module, and tis asorer is an enlosure ontaining te oolant, a rototye is made at te nit o Alied Resear in Renewale Energy in Gardaïa. Te seet and tue oniguration wi is adated in te design o lan termal olletors is used. Te galvanized steel was used or its low ost. Te advantages o tis yrid olletor are etter eat asortion and lower rodution ost omared to oter onigurations o yrids olletors [5, 6]. In tis aer, an attemt is made to investigate te termal erormane o te olletor studied y Touaek [3, 8]. A detailed termal model will e develoed to alulate te termal arameters o tis rototye. Some orretions are done on eat loss oeiients in order to imrove te termal model o a PV/T water and air olletor.. Numerial Aroa Fig. 1. Sows te simliied diagram o te new roosed PVT yrid olletor. It onsists o a monoristallin s otovoltai module (wit its tree layers: temered glass, layer o te ells wit te etylene vinyl aetate (EVA), and lay down Tedlar) tye (DTS50) o 1.9 m lengt and 0.33 m widt, and galvanized steel asorer laed at te lower art o te module, and tis asorer is an enlosure ontaining te oolant, wi an e air, water, or glyol. An insulation o te yrid olletor is neessary, it allows etter termal erormanes, and tis insulation is ensured y glass wool. Fig 1. Simliied diagram o new PV/T olletor In order to write te energy alane equation or ea omonent o a PV/T water olletor, te ollowing assumtions ave een made:

4 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) One dimensional eat ondution is good aroximation or te resent study. Te glass over is at uniorm temerature. Te mass low rate o te working luid is te same in all setions o te tues. Te material roerties o te glass, over, asorer, and te insulation are onstant. For an element o lengt dy in te diretion o low, te eat alane equations or ea omonent o (PV/T) solar water eating system wen is sujeted to te illumination G, seleting dq u te quantity extrat eat rom water: C For solar ells o PV module: T t G g A 1 T T A T T G a An exression or temerature deendent eletrial eiieny o a PV module Sott [9] is given y 0 re T T () e For to art o asorer surae Tas C A as rad as as as as as (3) t For te ottom art o asorer surae as T T A T T A T T Tas C Arad (4) t For water lowing troug te dut Te energy alane o lowing water inside te dut T M C A1 T as T A T Tas (5) t For te eat transer inside te water annel, in solar termal water olletors, te water annel ottom ( ) and to ( 1) eat transer oeiients are tyially assumed to e idential. Te luid eat transer oeiient in te annel is a untion o te Nusselt numer, Nu, luid termal ondutivity and ydrauli diameter D. At some loation long te low diretion te asored solar energy eats u te late to a temerature T. Energy is transerred rom te late to te amient air at Ta troug te ak loss oeiient, to te luid at T troug te onvetion eat transer oeiient, and to te low art o te asorer troug te linearized radiation eat transer oeiient rad(as-as). Energy is transerred to te low art o asorer rom te luid troug te eat transer oeiient 1. Te art o energy is lost to te amient air troug te omined radiation and onvetion oeiient. Te radiative eat transer oeiient term ( r) as een added to overall eat transer oeiient rom glass external to amient ( 1). Furter, te orresonding oeiient o onvetive loss aused y te wind an e alulated rom equation ( ). as as Tas Tas A Tas Ta A T as T e g (1) 1 1 g 1 r g Te onvetive eat lux deends on te wind seed and an e alulated y [31]: (6).8 3 (7) V w rad g T T T T (8) sky sky Te eetive temerature o te sky (T sky) is alulated rom te ollowing emirial relation [3]:

5 1094 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) T 1. 5 Tsky a (9) In te estimation o overall loss oeiient rom ell to asorer ( ), as een alulated rom Eq. (10) 1 ted ted A radiative loss exists rom te to to te ottom art o asorer surae rad(as_as). [33] rad 4 T as as In te estimation o overall ak loss oeiient ( ), te onvetive eat transer oeiient on te ak surae o PV/T, ( onv,) as een alulated rom Eq (7) 1 1 i tol (1) i tol onv, Solving equations exressing te onservation o energy or an element o volume etween te glass, ell, te asorer and te luid exressed in terms o dierent oeiient untion o 1,, 1,, rad(as-as) and T a, leads us to determine te and F R or te seond olletor oeiient o overall loss. dqu. mc F dt G T T ' F a dy G T T ' a dy Te Hottel-Willer model [30] is adoted ere. Te atual useul energy gain y te water is equal to te olletor eat removal ator time s maximum ossile useul energy gain. Tereore te eat olleted y te water an e rewritten as q u Were R G T Ta AF (15) 3 i rad rad as as as as 3 or tis olletor is not just te to loss oeiient in te asene o ak losses ut also aounts or eat transer etween te to and ottom o asorer surae. F ' rad as as rad as as Te amount o solar energy availale or te termal system is redued sine eletrial energy is extrated y te solar ells: A G g g v G A (18) T Te eat removal eiieny ator (F R) an e alulated as:. ' m C F A F R 1 ex. (19) A m C Were F R is te eat removal ator, deined as te ratio o eat extrated y te olletor to eat extrated wen te wole olletor is at luid inlet temerature. For a ixed mass low rate, F R and are almost onstant quantities (10) (11) (13) (14) (16) (17)

6 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) or a termal olletor. Tereore, i termal eiieny ( t) is lotted against (T it a)/g, a straigt line is otained. Te ell eiieny reresented as a untion o te module temerature. As is sown in te eqt (). Were te 0 is te reerene eiieny o te solar ell at T re =5 C wi is in our study 15%. Te temerature o te otovoltai anel may e written as : X1 X e G X 3Ta X Ti T 4 (0) Te exressions or X 1, X, X 3, and X 4 suggest tat tese sould e onstant. It an e noted tat a linear relationsi exists etween te temerature o te PV anel (T ) and eletrial eiieny ( e). For onstant value o solar radiation (G), te eletrial eiieny o te system an e exressed as: T i Ta e Y1 Y (1) G I Y 1, Y are onstant values, ten te variation o eletrial eiieny ( e) o te system wit T a and T i sould give a lane. Te limati, oerating and design arameters o te PV/T olletor during validation roess are desried in Tale 1. Tale1. Amient onditions and design used in simulations Solar PV/T olletor arameters Te solar radiation intensity at te reerene onditions, G re Te amient temerature at reerene onditions, T a,re Te lengt o PV/T olletor, Te widt o PV/T olletor, H Te solar ell temerature at reerene onditions, T ell,re Te eletrial eiieny at te reerene onditions, el,re Te tikness o glass over, g Te ondutivity o glass over, g Te transmittivity o glass over, g Te emissivity o glass, g Te emissivity o ell, module, ell Te asortivity o ell, module, Te tikness o silion solar ell, si Te ondutivity o silion solar ell, si Te asortivity o tedlar, T Te tikness o tedlar, T Te ondutivity o tedlar, T Te emissivity o asorer, Te tikness o asorer (galvanized iron), Te ondutivity o asorer, Te tikness o ak insulation, i Te ondutivity o ak insulation, i Te wind seed, V w Colleteur angle, Value 1000 W/m 98 K 1.9 m 0.33 m 98 K m 1 W/m K x10-5 m 131 W/m K m 163W/m K m 65 W/m K 0.05 m W/m K 1 m/s 35

7 1096 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) Tale. Te tyial results o omuter simulation rogram under te samle onditions o Tale 1, T i = T a = 300K, V w = 1m/s, G = 1000 W/m. Solar PV/T olletor arameters Case o air Te termal eiieny, t Te eletrial eiieny, el Te outlet air temerature, T o Te solar ell temerature, T Te rate o useul termal energy, Q u Te eletrial energy, E e Te solar asored lux, S Te eat aaity o lowing air, C Case o water Te termal eiieny, t Te eletrial eiieny, el Te outlet air temerature, T o Te solar ell temerature, T Te rate o useul termal energy, Q u Te eletrial energy, E e Te solar asored lux, S Te eat aaity o lowing water, C 3. Results and disussion Value 16.4 % 11.1 % K K W W W kj/kg K % % K K 3.83W W W /kg K From te resented results o Fig., we an see tat te maximum eletrial energy is reaed at 1.m. and is W owers Eele Eletrial energy (W) Eletrial eiieny Time () Fig. Te ourly variation o eletrial energy (Tin-Ta)/G Fig. 3. Variations o te eletrial eiieny aording to te redued temerature A simulation was erormed to redit te eletrial eiieny o PVT-anel. Fig. 3 sow eletrial eiieny variation, te ration T G (C W -1 m²) is te redued temerature, wit T T i Ta (K). At zero redued temerature it was ound to e 15.06%.

8 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) Inreasing te solar radiation intensity, termal ower o te PV/T-olletor inreases initially and ten dereases ater attaining solar radiation intensity o aout a maximum oint. Te Hourly variation o termal ower wit time in air and water eating are dislayed in Fig. 4. It was ound to e 69.36W in air eating and 3.83W in te mode o water eat exanger Qu water Qu air water air seul termal energy(w) Termal eiieny (%) Time (r) Fig.4 Te ourly variation o useul termal energy (Tin-Ta)/G Fig. 5 Variations o te termal eiieny aording to te redued temerature in te mode o water and air eat exanger Fig. 5 sows termal eiieny variation at PVT-anel, tese results are reerred to termal eiieny o water t/w in te mode o water eat exanger, and air t/a eat extration, aording to te redued temerature. Te PV/T air olletor is oviously erorming oorest at zero redued temerature and PVT water olletor reresents a iger value. 4. Exerimental study To study exerimentally te PVT yrid solar olletor, a rototye is made at te nit o Alied Resear in Renewale Energy. It is onstituted y te monorystalline otovoltai module (DTS 50 tye) elow wi irulates te air. Fig. 6 Potogra o te rototye o yrid PV/T air olletor at RAER nity, Gardaïa. Te asorer is realized wit te galvanized iron o ig quality, allowing a good transer o eat wit lower ost omared to oer. Aims to inrease its eletri and termal onversion energy eetiveness wit a low ost

9 1098 H. Ben eik el oine et al. / Energy Proedia 74 ( 015 ) omared to te already existing yrid olletor. Te measured data inlude te solar radiation intensity, amient temerature, inlet and outlet air temerature; te simulated values o outlet air temerature, in resent work ave een validated y teir orresonding exerimental values in Re. [3]. Te test measurements were made on Setemer 008. Te outut temerature reaed 37 C or an inut o 34 C and an amient temerature (T a) o 33C. te inrease in te temerature o te oolant o an average o 3 C etween te entry and te exit. Te exerimental results or a PV/T air olletor make it ossile to veriy te results otained y our omuter simulation. 5. Conlusion In tis aer, te erormane evaluation o a PV/T olletor was arried out. A detailed termal model was develoed to alulate te termal and eletrial arameters o a tyial PV/T olletor. Some orretions were done on eat loss oeiients in order to imrove te termal model o a PV/T olletor. A natural irulation o air is te easiest and eaest way to remove te eat at te module and onsequently inrease te eiieny. Te used asorer satisying simliity and ost onstraints, it is made y galvanized iron wi is eaer and te manuaturing time is redued omared wit te lassial yrid olletors. Reerenes [1] Zondag, H.A., Bakker, M., Van Helden, W.G.J., Aolter. P., Eisenmann, W., Fener, H., 005. PVT roadma: a Euroean guide or te develoment and market introdution o PVT tenology. In: Proeedings o (CD) 0 t Euroean Potovoltai Solar Energy Conerene. [] A.A. Hegazy, Comarative study o te erormanes o our otovoltai/termal solar air olletors, Energy Conversion and Management 41(000) [3] J.K. Tonui, Y. Trianagnostooulos, Air-ooled PV/T solar olletors wit low ost erormane imrovements, Solar Energy 81 (007) [4] J.K. Tonui, Y. Trianagnostooulos, Imroved PV/T solar olletors wit eat extration y ored or natural air irulation, Renewale Energy 3 (007) [5] A. Tiwari, M.S. Soda, A. Candra, J.C. Josi, Perormane evaluation o oto-voltai/termal solar air olletor or omosite limate o India, Solar Energy Materials and Solar Cells 90 (006) [6] V. Raman, G.N. Tiwari, ie yle ost analysis o HPVT air olletor under dierent Indian limati onditions, Energy Poliy 36 (008) [7] V. Raman, G.N. Tiwari, A omarison study o energy and exergy erormane o a yrid otovoltai doule-ass and single-ass air olletor, International Journal o Energy Resear 33 (009) [8] F. Saraddi, S. Faraat, H. Ajam, A. Bezadmer, M.M. Adeli, An imroved termal and eletrial model or a solar otovoltai/termal (PV/T) air olletor, Alied Energy 87 (010) [9] F. Saraddi, S. Faraat, H. Ajam, A. Bezadmer, Exergeti erormane assessment o a solar otovoltai/termal (PV/T) air olletor, Energy and Buildings4 (010) [10] R. Kumar, M.A. Rosen, Perormane evaluation o a doule ass PV/T solar air eater wit and witout ins, Alied Termal Engineering 31 (011) [11] A. Al-Alili, Y. Hwang, R. Radermaer, I. Kuo, A ig eiieny solar air onditioner using onentrating otovoltai/termal olletors, Alied Energy 93(01) [1] B.J. Huang, T.H. in, W.C. Hung, F.S. Sun, Perormane evaluation o solar otovoltai/termal systems, Solar Energy 70 (001) [13] H.A. Zondag, D.W. de Vries, W.G.J. van Helden, R.J.C. van Zolingen, A.A. vansteenoven, Te termal and eletrial yield o a PV termal olletor, SolarEnergy 7 (00) [14] H.A. Zondag, D.W. de Vries, W.G.J. van Helden, R.J.C. van Zolingen, A.A. vansteenoven, Te yield o dierent omined PV-termal olletor designs, Solar Energy 74 (003) [15] S.A. Kalogirou, Y. Trianagnostooulos, Hyrid PV/T solar systems or domesti ot water and eletriity rodution, Energy Conversion and Management 47(006) [16] J. Ji, J.P. u, T.T. Cow, W. He, G. Pei, A sensitivity study o a yrid otovoltai/termal water-eating system wit natural irulation, Alied Energy 84 (007) 37. [17] T.T. Cow, W. He, J. Ji, An exerimental study o aade-integrated otovoltai/water-eating system, Alied Termal Engineering 7 (007) [18] B. Roles-Oamo, E. Ruíz-Vasquez, H. Canseo-Sánez, R.C. Cornejo-Meza,G. Traaga-Martinez, F.J. Garia-Rodriguez, J. González- Hernandez, Y.V. Voro-iev, Potovoltai/termal solar yrid system wit iaial PV module and transarent lane olletor, Solar Energy Materials and Solar Cells 91 (007) [19] E. Erdil, M. Ilkan, F. Egelioglu, An exerimental study on energy generation wit a otovoltai (PV)-solar termal yrid system, Energy 33 (008) [0] S. Duey, G.N. Tiwari, Analysis o PV/T lat late water olletors onneted in series, Solar Energy 83 (009) [1] R. Santergen, C.C.M. Rindt, H.A. Zondag, R.J.C. van Zolingen, Detailed analysis o te energy yield o systems wit overed seet-andtue PVT olletors, Solar Energy 84 (010)

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