Yadda ƙwayoyin rana suke aiki

Kwayoyin hasken rana sha hasken rana don samar da ayyukan batura na yau da kullun. Amma ba kamar batura na gargajiya ba, ƙarfin fitarwa da matsakaicin ƙarfin fitarwa na batura na gargajiya suna daidaitawa, yayin da ƙarfin fitarwa, halin yanzu, da ƙarfin sel na hasken rana suna da alaƙa da yanayin haske da wuraren aiki. Saboda haka, don amfani da ƙwayoyin hasken rana don samar da wutar lantarki, dole ne ku fahimci dangantakar yanzu-voltage da ka'idar aiki na ƙwayoyin rana.

Hasken haske na hasken rana:

Tushen makamashi na sel hasken rana shine hasken rana, don haka ƙarfi da nau'ikan hasken rana da ke faruwa suna ƙayyade ƙarfin halin yanzu da ƙarfin wutar lantarki daga tantanin rana. Mun san cewa idan aka sanya abu a karkashin rana, yana samun hasken rana ta hanyoyi biyu, daya hasken rana kai tsaye, dayan kuma ya watsar da hasken rana bayan ya watsar da wasu abubuwa a saman. A cikin yanayi na al'ada, hasken abin da ya faru kai tsaye ya kai kusan kashi 80% na hasken da tantanin rana ke samu. Don haka, tattaunawarmu ta gaba kuma za ta mayar da hankali ne kan fallasa hasken rana kai tsaye.

Za'a iya bayyana ƙarfin da bakan hasken rana ta hanyar ruɗaɗɗen bakan, wanda shine ƙarfin hasken kowane tsayin raka'a a kowane yanki (W/㎡um). Ƙarfin hasken rana (W/㎡) shine jimlar duk tsawon tsayin daka na hasken bakan. Hasken bakan na hasken rana yana da alaƙa da matsayi da aka auna da kusurwar rana dangane da saman duniya. Hakan ya faru ne domin hasken rana zai mamaye sararin samaniya kuma ya warwatsa kafin ya isa saman duniya. Abubuwa biyu na matsayi da kusurwa gabaɗaya suna wakiltar abin da ake kira iska (AM). Don hasken rana, AMO yana nufin halin da ake ciki a sararin samaniya lokacin da rana ke haskakawa kai tsaye. Ƙarfin haskensa yana da kusan 1353 W/㎡, wanda yayi daidai da tushen hasken da hasken baƙar fata ke samarwa tare da zafin jiki na 5800K. AMI yana nufin yanayin da ke saman ƙasa, lokacin da rana ke haskakawa kai tsaye, ƙarfin hasken yana kusan 925 W/m2. AMI.5 yana nufin yanayin da ke saman ƙasa, lokacin da rana ta faru a kusurwar digiri 45, ƙarfin hasken yana kusan 844 W/m2. Ana amfani da AM 1.5 gabaɗaya don wakiltar matsakaicin hasken rana a saman duniya. Samfurin da'ira mai amfani da hasken rana:

Lokacin da babu haske, tantanin hasken rana yana yin aiki kamar pn junction diode. Dangantakar ƙarfin lantarki na halin yanzu na diode manufa za a iya bayyana azaman

Inda nake wakiltar halin yanzu, V yana wakiltar wutar lantarki, Is shine saturation current, da VT=KBT/q0, inda KB ke wakiltar BoItzmann akai-akai, q0 shine naúrar wutar lantarki, kuma T shine zafin jiki. A zafin jiki, VT=0.026v. Ya kamata a lura da cewa an ayyana jagorancin Pn diode halin yanzu don gudana daga nau'in P-type zuwa nau'in n a cikin na'urar, kuma an bayyana ma'auni mai kyau da korau na ƙarfin lantarki a matsayin yiwuwar tashar P-type. rage karfin tashar n-type. Saboda haka, idan aka bi wannan ma'anar, lokacin da ƙwayar rana ke aiki, ƙimar ƙarfin ƙarfinsa yana da kyau, ƙimarsa a halin yanzu ba ta da kyau, kuma IV curve yana cikin quadrant na huɗu. Dole ne a tunatar da masu karatu a nan cewa abin da ake kira manufa diode ya dogara ne akan yawancin yanayi na jiki, kuma ainihin diodes za su sami wasu abubuwan da ba su dace ba waɗanda suka shafi dangantakar da ke tsakanin na'urar a halin yanzu-voltage na na'ura, irin su ƙarni-recombination current, a nan Mun yi nasara' t tattauna shi da yawa. Lokacin da tantanin rana ya fallasa zuwa haske, za a sami photocurrent a cikin pn diode. Domin ginannen hanyar filin lantarki na mahaɗin pn daga nau'in n-type zuwa nau'in p-type, nau'ikan ramukan electron da aka samar ta hanyar ɗaukar photon za su yi tafiya zuwa ƙarshen nau'in n, yayin da ramukan za su gudu zuwa p. - irin karshen. Nau'in photocurrent da su biyun suka kirkira zai gudana daga nau'in n-type zuwa nau'in p-type. Gabaɗaya, jagorar halin yanzu na diode an ayyana shi azaman gudana daga nau'in p-n-n. Ta wannan hanyar, idan aka kwatanta da madaidaicin diode, photocurrent da ke haifar da tantanin rana a lokacin da aka haskaka shi ne mummunan halin yanzu. Dangantakar wutar lantarki na yanzu na tantanin rana shine madaidaicin diode tare da mummunan hoto na IL, wanda girmansa shine:

Ma'ana, lokacin da babu haske, IL=0, tantanin hasken rana kawai diode ne kawai. Lokacin da tantanin rana ya kasance gajere, wato, V=0, gajeriyar kewayawa shine Isc=-IL. Wato lokacin da tantanin hasken rana ya yi gajeriyar kewayawa, gajeriyar kewayawa ita ce hasken da ya faru. Idan tantanin hasken rana buɗaɗɗe ne, wato idan I=0, buɗaɗɗen wutar lantarkinsa shine:

Hoto 2. Daidai da kewaye na hasken rana: (a) ba tare da, (b) tare da jerin da shunt resistors. Dole ne a jaddada a nan cewa buɗaɗɗen wutar lantarki da gajeriyar kewayawa su ne mahimman sigogi guda biyu na halayen ƙwayoyin rana.

Fitar da wutar lantarki na tantanin rana shine samfurin halin yanzu da ƙarfin lantarki:

Babu shakka, fitowar wutar lantarki ta tantanin rana ba ƙayyadadden ƙima ba ne. Ya kai matsakaicin ƙima a wani wurin aiki mai ƙarfin lantarki na yanzu, kuma ana iya ƙaddara iyakar ƙarfin fitarwa Pmax ta dp/dv=0. Zamu iya yanke cewa ƙarfin fitarwa a matsakaicin ƙarfin fitarwa Pmax shine:

kuma abin fitarwa shine:

Matsakaicin ƙarfin fitarwa na tantanin rana shine:

Ingancin tantanin rana yana nufin rabon tantanin hasken rana yana canza ikon Fin hasken abin da ya faru zuwa mafi girman wutar lantarki, wato:

Gabaɗaya ma'aunin ingancin aikin rana yana amfani da tushen haske mai kama da hasken rana tare da fil = 1000W/㎡.

Gwaji, dangantakar wutar lantarki ta halin yanzu na sel hasken rana baya bin bayanin ka'idar da ke sama gaba ɗaya. Wannan shi ne saboda na'urar photovoltaic kanta tana da abin da ake kira juriya da juriya na shunt. Ga kowane abu na semiconductor, ko tuntuɓar tsakanin semiconductor da ƙarfe, babu makawa za a sami juriya mafi girma ko ƙarami, wanda zai samar da jerin juriya na na'urar hotovoltaic. A gefe guda, duk wata hanya ta yanzu ban da madaidaicin Pn diode tsakanin ingantattun na'urori masu inganci da na'urar daukar hoto za su haifar da abin da ake kira leakage current, kamar na yanzu-recombination current a cikin na'urar. , yanayin sake haɗawa na yanzu, rashin cikar keɓewar na'urar, da mahadar shigar ƙarfe.

Yawancin lokaci, muna amfani da juriya na shunt don ayyana ɗigogin halin yanzu na ƙwayoyin rana, wato, Rsh=V/Ileak. Mafi girman juriya na shunt shine, ƙarami na ɗigogi na yanzu shine. Idan muka yi la'akari da juriya na haɗin gwiwa Rs da shunt juriya Rsh, ana iya rubuta dangantaka ta halin yanzu-voltage na hasken rana kamar:

Hakanan zamu iya amfani da siga guda ɗaya kawai, abin da ake kira cika factor, don taƙaita duka tasirin juriya da juriya na shunt. ma'ana kamar:

A bayyane yake cewa ma'aunin cika shine matsakaicin idan babu jerin resistor kuma juriyar shunt ba ta da iyaka (babu leaka halin yanzu). Duk wani karuwa a cikin juriya na juriya ko raguwa a cikin juriya na shunt zai rage ma'aunin cikawa. Ta wannan hanyar,. Ana iya bayyana ingancin ƙwayoyin hasken rana ta mahimman sigogi guda uku: buɗaɗɗen wutar lantarki Voc, ɗan gajeren da'ira na yanzu, da cika factor FF.

Babu shakka, don inganta ingantaccen aikin tantanin halitta, ya zama dole a lokaci guda ƙara ƙarfin wutar lantarki na buɗewa, gajeriyar kewayawa (wato, photocurrent), da kuma cika abubuwa (wato, rage juriya na jerin abubuwan da ke faruwa a halin yanzu).

Buɗaɗɗen wutar lantarki da gajeriyar kewayawa: Idan aka yi la’akari da dabarar da ta gabata, buɗaɗɗen wutar lantarki na tantanin rana ana ƙaddara ta hanyar hoto na yanzu da cikakken tantanin halitta. Daga mahangar ilimin kimiyyar semiconductor, buɗaɗɗen wutar lantarki daidai yake da bambancin makamashi na Fermi tsakanin electrons da ramuka a yankin cajin sararin samaniya. Dangane da jikewar halin yanzu na ingantaccen Pn diode, zaku iya amfani da:

bayyana. inda q0 ke wakiltar cajin naúrar, ni yana wakiltar ƙaddamarwar mai ɗaukar hoto na semiconductor, ND da NA kowannensu yana wakiltar ma'auni na mai bayarwa da mai karɓa, Dn da Dp kowannensu yana wakiltar ma'auni na rarrabawa na electrons da ramuka, bayanin da ke sama yana ɗaukan n. - Al'amarin inda duka nau'in yanki da nau'in p-type duka suna da faɗi. Gabaɗaya, ga ƙwayoyin hasken rana ta amfani da nau'in p-type, yankin n-type ɗin ba shi da zurfi sosai, kuma wannan magana na sama yana buƙatar gyara.

Mun ambata a baya cewa lokacin da hasken rana ya haskaka, ana samar da photocurrent, kuma photocurrent shine rufaffiyar kewayawa a cikin dangantakar yanzu-voltage na tantanin halitta. Anan zamuyi bayanin asalin photocurrent a takaice. Matsakaicin ƙirƙira na masu ɗauka a cikin juzu'in naúrar kowane lokaci naúrar (naúrar m -3 s -1) ana ƙididdige shi ta hanyar ƙimar ɗaukar haske, wato

Daga cikin su, α yana wakiltar ma'aunin ɗaukar haske, wanda shine ƙarfin abubuwan da suka faru na photons (ko photon flux density), kuma R yana nufin ma'auni na tunani, don haka yana wakiltar ƙarfin photons da ba a bayyana ba. Manyan hanyoyi guda uku da ke haifar da photocurrent su ne: yaduwar wutar lantarki na yan tsirarun dillalan lantarki a cikin yankin p-type, difffusion current na tsirarun dillalan ramuka a yankin n-type, da zazzagewar electrons da ramuka a yankin cajin sararin samaniya. halin yanzu. Saboda haka, photocurrent za a iya kusan bayyana kamar:

Daga cikin su, Ln da Lp kowanne yana wakiltar tsayin yaduwa na electrons a cikin yankin p-type da ramuka a cikin nau'in n, kuma shine fadin yankin cajin sararin samaniya. Taƙaice waɗannan sakamakon, muna samun sauƙin magana don buɗaɗɗen wutar lantarki:

inda Vrcc ke wakiltar ƙimar sake haɗewar nau'ikan ramukan lantarki a kowace juzu'in raka'a. Tabbas wannan sakamako ne na dabi'a, saboda buɗaɗɗen wutar lantarki yana daidai da bambancin makamashi na Fermi tsakanin electrons da ramuka a cikin yankin cajin sararin samaniya, kuma bambancin makamashin Fermi tsakanin electrons da ramuka ana ƙaddara ta hanyar jigilar jigilar kayayyaki da ƙimar sake haɗawa. .