DEG RA DA TION EF FECTS OF THE OUT PUT ELEC TRI CAL
CHAR AC TER IS TICS OF Si SO LAR CELLS AS A RE SULT OF
ION IZ ING RA DI A TION UN DER LOW LIGHT CON DI TIONS
by
Nebojša M. STOJANOVI] 1, Biljana B. SIMI]1, Koviljka Dj. STANKOVI]1*, and Djordje R. LAZAREVI] 2
1
Fac ulty of Elec tri cal En gi neer ing, Uni ver sity of Bel grade, Ser bia 2
De part ment of Ra di a tion and En vi ron men tal Pro tec tion, Vin~a In sti tute of Nu clear Sci ences, Uni ver sity of Bel grade, Bel grade, Ser bia
Sci en tific paper DOI: 10.2298/NTRP1503210S
This pa per pres ents re sults of ra di a tion re sis tance of dif fer ent types of com mer cially avail able sin gle- and poly-crys tal line sil i con so lar cells. Sam ple cells were sub jected to gamma ra di a tion from gamma ra di a tion source 60Co. Char ac ter is tic pa ram e ters of so lar cells were ex tracted from ob tained I-V curves: open cir cuit volt age, short cir cuit cur rent, max i mum power point volt age and cur rent, ef fi ciency, fill fac tor, and se ries re sis tance. Ob tained re sults show the level of pa ram e ters' deg ra da tion with pur pose of in creas ing so lar cells ap pli ca tions in ra di a -tion en vi ron ments.
Key words: elec tri cal char ac ter is tic, ra di a tion ef fect, so lar cell
IN TRO DUC TION
In or der to pro duce high ef fi ciency so lar cells, pho to vol taic (PV) tech nol ogy is di rected, at first, to in -ves ti ga tion of fun da men tal cell's pa ram e ters (such as life time of charge car ri ers, their trans port pro cesses, gen er a tion and an ni hi la tion of elec tronhole pairs, in -ter nal se ries and par al lel re sis tance, etc.) caused by im -pu ri ties, de fects, and dop ants dur ing the so lar cells man u fac tur ing [14]. Re la tion ship be tween fun da -men tal pa ram e ters and out put char ac ter is tics (open cir cuit volt age, short cir cuit cur rent den sity, out put power in max i mum power point, volt age in max i mum power point, cur rent in max i mum power point, fill fac -tor, and ef fi ciency) is the most im por tant stage while in ves ti gat ing op er at ing per for mance of so lar cells.
PV so lar cells are of ten ex posed to ra di a tion dur ing ex ploi ta tion. Since their work ing con di tions usu -ally do not al low reg u lar main te nance, sta bil ity of their out put elec tri cal char ac ter is tics is very im por tant. There fore, in ves ti ga tion of ra di a tion re sis tance of so -lar cells is in ter est ing not only for pre dic tion of so -lar cells op er at ing life time and their endoflife char ac ter -is tics, but also for im prove ments in de sign of so lar cells in tended for use in hos tile working conditions, such as radiation environment [5-7].
The aim of this pa per is to in ves ti gate the ra di a -tion re sis tance of dif fer ent types of com mer cially avail able sin glecrys tal line and polycrys tal line sil i con so lar cells. Sam ples were sub jected to gamma ra -di a tion from 60Co source and re ceived a few dif fer ent dose lev els. Out put pa ram e ters of so lar cells were ex -tracted from re corded I-V curves, in clud ing: open cir -cuit volt age, short cir -cuit cur rent, ef fi ciency, fill fac tor, and se ries re sis tance.
EX PER I MENT
Ex per i men tal work was based on re cord ing I-V char ac ter is tics of so lar cells, vary ing mea sure ments pa ram e ters: so lar cell type, light in ten sity, and ra di a -tion dose. I-V curves rep re sent the ba sic and most com -mon way to ob tain, in a fast and sim ple way, va ri ety of data re lated both to out put and to fun da men tal pa ram e -ters of so lar cells. Sam ples marked S1 and S2 are sin -gle-crys tal line sil i cone so lar cells while sam ple P1 is poly-crys tal line sil i cone so lar cell. Light in ten sity was var ied by chang ing the dis tance of sam ple cells from the light source, and was con trolled by us ing a cal i -brated stan dard cell and lux-me ter Laybold (sen sor F = 0.76). Val ues of light flux used dur ing the ex per i -ment were of 32 W/m2 and 58 W/m2 for sin glecrys tal -line sil i cone so lar cells and 101 W/m2 and 338 W/m2 for poly-crys tal line sil i cone so lar cell.
N. M. Stojanovi}, et al.: Deg ra da tion Ef fects of the Out put Elec tri cal ...
210 Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2015, Vol. 30, No. 3, pp. 210-213
Tem per a ture of the sam ple was mon i tored by ther mo cou ple and volt age and cur rent mea sure ments were per formed by Metron M890C dig i tal multime -ters. Ir ra di a tion of sam ples was car ried out in 60Co gamma ra di a tion field with doses rang ing from 10 Gy to 4353 kGy. I-V curves were re corded be fore ini tial ir -ra di a tion, and af ter each ir -ra di a tion step.
All mea sure ments were per formed un der sta ble con di tions. The ex panded com bined un cer tainty of each pro ce dure did not ex ceed 5 % [8, 9].
Pa ram e ters ob served be fore and af ter ir ra di a tion were: open cir cuit volt age (Voc), short cir cuit cur rent den sity (Jsc), in ter nal se ries re sis tance (Rs), out put power in max i mum power point (Pmpp), volt age in max i mum power point (Vmpp), cur rent in max i mum power point (Jmpp), fill fac tor (FF), and ef fi ciency (h).
RE SULTS AND DISCUSSIONS
Re sults of the ob served pa ram e ters for sin -gle-crys tal line sil i cone so lar cells be fore ir ra di a tion and af ter re ceiv ing cu mu la tive doses of 10, 110, and 490 Gy, un der light flux of 32 W/m2 and 58 W/m2 (white light) for sam ples S1 and S2 are given in tabs. 1 and 2, re spec tively.
Ta ble 3 shows re sults ob tained for sam ple P1, be fore ir ra di a tion and af ter re ceiv ing cu mu la tive doses of 905 kGy and 5258 kGy, un der light flux of 101 W/m2 and 338 W/m2.
Ob tained re sults for sin gle-crys tal line (S1 and S2) and poly-crys tal line (P1) sil i con so lar cells show the out put elec tri cal char ac ter is tics in hos tile work ing con di tions (re duced light in ten sity and pres ence of
N. M. Stojanovi}, et al.: Deg ra da tion Ef fects of the Out put Elec tri cal ...
Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2015, Vol. 30, No. 3, pp. 210-213 211
Ta ble 1. Mea sured pa ram e ters of sam ple S1 be fore ir ra di a tion and af ter re ceiv ing cu mu la tive doses of 10, 110, and 490 Gy,
un der light flux of 32 W/m2 and 58 W/m2
Flux [Wm–2] 32 58
Dose [Gy] 0 10 110 490 0 10 110 490
Voc [mV] 409 412 396 398 409 412 396 398
Jsc [mAcm–2] 0.897 0.896 0.932 0.913 1.686 1.735 1.577 1.493
Rs [ W] 5.59 7.57 8.00 7.24 5.59 7.57 8.00 7.24
Pmpp [Wm–2] 2.313 2.206 2.117 2.152 4.970 5.253 4.521 4.238
Vmpp [mV] 325.98 324.34 312.16 296.84 366.52 370.29 358.47 349.21
Jmpp [mAcm–2] 0.710 0.680 0.678 0.725 1.356 1.419 1.261 1.214
FF 0.630 0.598 0.573 0.592 0.652 0.659 0.638 0.638
h [%] 7.198 6.867 6.598 6.696 8.533 9.019 7.761 7.267
Ta ble 2. Mea sured pa ram e ters of sam ple S2 be fore ir ra di a tion and af ter re ceiv ing cu mu la tive doses of 10, 110, and 490 Gy,
un der light flux of 32 W/m2 and 58 W/m2
Flux [Wm–2] 32 58
Dose [Gy] 0 10 238 0 10 238
Voc [mV] 447 444 391 476 477 432
Jsc [mAcm–2] 0.973 0.956 0.756 1.789 1.658 1.311
Rs [ W] 3.63 4.2 5.72 1.76 2.27 3.22
Pmpp [Wm–2] 2.967 2.804 1.893 6.099 5.281 3.682
Vmpp [mV] 359.63 356.33 302.17 399.54 396.67 342.79
Jmpp [mAcm–2] 0.825 0.787 0.627 1.526 1.331 1.074
FF 0.683 0.660 0.632 0.716 0.668 0.650
h [%] 9.23 8.73 5.89 10.47 9.07 6.32
Ta ble 3. Mea sured pa ram e ters of sam ple P1 be fore ir ra di a tion and af ter re ceiv ing cu mu la tive doses of 905 Gy and 5258
Gy, un der light flux of 101 W/m2 and 338 W/m2
Flux [Wm–2] 101 338
Dose [Gy] 0 905 5258 0 905 5258
Voc [mV] 424 356 348 477 421 387
Jsc [mAcm–2] 1.906 1.353 1.074 6.820 4.638 4.085
Rs [ W] 4.14 5.02 5.33 0.76 1.15 1.13
Pmpp [Wm–2] 4.853 3.249 2.352 23.080 12.931 10.854
Vmpp [mV] 319.82 248.04 256.57 389.89 341.75 330.34
Jmpp [mAcm–2] 1.518 1.310 0.917 5.920 3.784 3.286
FF 0.600 0.659 0.630 0.709 0.663 0.687
ion iz ing ra di a tion). Vari a tions of these pa ram e ters are shown in re spect both to light flux and to re ceived ra di -a tion doses.
There are three typ i cal zones of ac cu mu lated ra di -a tion doses th-at c-an be dis tin guished re g-ard ing the so l-ar cells level of deg ra da tion: small, me dium and high doses. At the level of small doses, so lar cells did not show sig nif i cant changes in out put char ac ter is tics, while at the level of me dium doses sam ples showed sig -nif i cant deg ra da tion of out put char ac ter is tics. Fi nally, at high doses level, so lar cells showed re duced deg ra da -tion com pared to trends dis played on lower doses.
All the ex am ined char ac ter is tics showed deg ra da tion with in creased doses of gamma ra di a tion, ex -cept for fill fac tor val ues, which showed rel a tively steady values.
In ad di tion, dif fer ent types of so lar cells ex posed to sim i lar doses of ra di a tion showed dif fer ent lev els of change. With re spect to to tal doses of gamma ra di a tion, short cir cuit cur rents have dropped to 45 %50 % of ini -tial val ues with sin gle-crys tal line, and to 40 %-60 % with poly-crys tal line sam ples. Open cir cuit volt age dropped to 81 %- 83 % with sin gle- crys tal line and to 75 %82 % with polycrys tal line cells, and the ef fi ciency dropped to 36 %42 % of ini tial val ues for sin -gle- crys tal line and 23 %-47 % for poly-crys tal line cells. This re sult is use ful for de ter mi na tion of the qual -ity of so lar cells.
CON CLU SIONS
All the ex am ined ra di a tion re sis tance char ac ter is -tics of com mer cially avail able sin gle-crys tal line and poly-crys tal line sil i con so lar cells showed deg ra da tion with in creased doses of gamma ra di a tion, ex cept for fill fac tor val ues, which showed rel a tively steady val ues. With re spect to to tal doses of gamma ra di a tion, short cir cuit cur rents have dropped to 45 %-50 % of ini tial val ues with sin gle-crys tal line, and to 40 %-60 % with poly-crys tal line sam ples. Open cir cuit volt age dropped to 81 %-83 % with sin gle- and to 75 %-82 % with poly-crys tal line cells, and the ef fi ciency dropped to 36 %-42 % of ini tial val ues for sin gle- and 23 %-47 % for poly-crys tal line cells.
Re sults pre sented in this pa per pro vide use ful data re lated to deg ra da tion ef fects of ra di a tion on out -put elec tri cal char ac ter is tics of sil i cone so lar cells, thus en abling pre dic tion of be hav ior of so lar cells ex posed to in creased lev els of ra di a tion and pos si ble es ti -ma tion of their operating lifetime.
AC KNOWL EDG EMENTS
The Min is try of Ed u ca tion, Sci ence and Tech no log i cal De vel op ment of the Re pub lic of Ser bia sup -ported this work un der con tract 171007.
AU THOR CONTRIBUTIONS
The o ret i cal anal y sis was car ried out by N. M. Stojanovi}, B. B. Simi}, and K. Dj. Stankovi}. Ex per i -ments were car ried out by B. B. Simi} and Dj. R. Lazarevi}. All of the au thors have ana lysed and dis -cussed the re sults. The manu script was writ ten by N. M. Stojanovi} and B. B. Simi}. The ta bles were pre -pared by N. M. Stojanovi}.
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Re ceived on June 19, 2015 Ac cepted on Sep tem ber 2, 2015
N. M. Stojanovi}, et al.: Deg ra da tion Ef fects of the Out put Elec tri cal ...
N. M. Stojanovi}, et al.: Deg ra da tion Ef fects of the Out put Elec tri cal ...
Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2015, Vol. 30, No. 3, pp. 210-213 213
Neboj{a M. STOJANOVI], Biqana B. SIMI], Koviqka \. STANKOVI], \or|e R. LAZAREVI]
EFEKTI DEGRADACIJE IZLAZNIH ELEKTRI^NIH OSOBINA Si SOLARNIH ]ELIJA KAO REZULTAT JONIZUJU]EG ZRA^EWA U
USLOVIMA NISKOG OSVETQAVAWA
U radu su prikazani rezultati istra`ivawa radijacione otpornosti razli~itih tipova komercijalno dostupnih monokristalnih i polikristalnih silicijumskih solarnih }elija. Uzorci }elija podvrgnuti su gama zra~ewu iz izvora 60Co. Karakteristi~ni parametri solarnih
}elija izvedeni su iz dobijenih I-V krivih: napon otvorenog kola, struja kratkog spoja, ta~ka maksimalnog napona i struje, efikasnost, faktor ispune i serijska otpornost. Dobijeni rezultati prikazuju nivo degradacije parametara silicijumskih solarnih }elija, u ciqu pove}awa wihove primene u uslovima zra~ewa.
