太陽能光伏發電原理
太陽能電池與蓄電池組成系統的電(dian)源單元,因(yin)此蓄電(dian)池性能直接影(ying)響著系統工作(zuo)特性。
(1)電(dian)(dian)(dian)池(chi)(chi)(chi)單(dan)元:由于技術(shu)和(he)材料原因,單(dan)一(yi)電(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)發電(dian)(dian)(dian)量是(shi)十(shi)分有限的(de)(de),實用中(zhong)(zhong)的(de)(de)太(tai)陽(yang)(yang)能電(dian)(dian)(dian)池(chi)(chi)(chi)是(shi)單(dan)一(yi)電(dian)(dian)(dian)池(chi)(chi)(chi)經串、并(bing)聯組(zu)(zu)成的(de)(de)電(dian)(dian)(dian)池(chi)(chi)(chi)系(xi)統(tong),稱為(wei)電(dian)(dian)(dian)池(chi)(chi)(chi)組(zu)(zu)件(jian)(jian)(陣列)。單(dan)一(yi)電(dian)(dian)(dian)池(chi)(chi)(chi)是(shi)一(yi)只硅晶體(ti)(ti)(ti)二(er)極管,根據半導(dao)體(ti)(ti)(ti)材料的(de)(de)電(dian)(dian)(dian)子學特性(xing),當(dang)太(tai)陽(yang)(yang)光照(zhao)射到由P型和(he)N型兩種不同導(dao)電(dian)(dian)(dian)類型的(de)(de)同質半導(dao)體(ti)(ti)(ti)材料構成的(de)(de)P-N結(jie)上(shang)時,在(zai)(zai)一(yi)定的(de)(de)條件(jian)(jian)下(xia),太(tai)陽(yang)(yang)能輻射被半導(dao)體(ti)(ti)(ti)材料吸(xi)收,在(zai)(zai)導(dao)帶(dai)和(he)價帶(dai)中(zhong)(zhong)產生非平衡載(zai)流(liu)(liu)子即電(dian)(dian)(dian)子和(he)空穴(xue)。同于P-N結(jie)勢(shi)壘區存在(zai)(zai)著較(jiao)強的(de)(de)內建(jian)(jian)靜電(dian)(dian)(dian)場(chang),因而能在(zai)(zai)光照(zhao)下(xia)形(xing)成電(dian)(dian)(dian)流(liu)(liu)密度J,短路電(dian)(dian)(dian)流(liu)(liu)Isc,開路電(dian)(dian)(dian)壓Uoc。若在(zai)(zai)內建(jian)(jian)電(dian)(dian)(dian)場(chang)的(de)(de)兩側面引出(chu)電(dian)(dian)(dian)極并(bing)接上(shang)負載(zai),理論上(shang)講由P-N結(jie)、連接電(dian)(dian)(dian)路和(he)負載(zai)形(xing)成的(de)(de)回路,于是(shi)就有“光生電(dian)(dian)(dian)流(liu)(liu)”流(liu)(liu)過(guo),太(tai)陽(yang)(yang)能電(dian)(dian)(dian)池(chi)(chi)(chi)組(zu)(zu)件(jian)(jian)就實現了對(dui)負載(zai)的(de)(de)功(gong)率P輸(shu)出(chu)。
(2)電能儲存單元:太陽能電池產生的(de)(de)直流電(dian)(dian)先進(jin)入蓄(xu)電(dian)(dian)池儲存,蓄(xu)電(dian)(dian)池的(de)(de)特(te)(te)性影(ying)響著系統(tong)的(de)(de)工作效率和(he)特(te)(te)性。蓄(xu)電(dian)(dian)池技術是十分成(cheng)熟的(de)(de),但(dan)其容(rong)量要(yao)受到末端需電(dian)(dian)量,日(ri)照時(shi)(shi)間(jian)(發電(dian)(dian)時(shi)(shi)間(jian))的(de)(de)影(ying)響。因(yin)此(ci)蓄(xu)電(dian)(dian)池瓦時(shi)(shi)容(rong)量和(he)安(an)時(shi)(shi)容(rong)量由預(yu)定的(de)(de)連續無日(ri)照時(shi)(shi)間(jian)決定。
設置原理
太陽(yang)能光伏發電系(xi)統的設計需要考慮的因素(su):
1、需要考(kao)慮太陽能光伏發電系(xi)統使用的地方以及該地日光輻射(she)情(qing)況;
2、需要考(kao)慮太(tai)陽能光伏發電系(xi)統需要承(cheng)載(zai)的負(fu)載(zai)功(gong)率;
3、系統所輸出電壓,以及考(kao)慮應該使(shi)用直流(liu)電還是交流(liu)電;
4、系統(tong)每天需要工作的小時(shi)數;
5、如遇到沒有日光照射的陰(yin)雨天(tian)氣,系(xi)統需連續供電多少天(tian);
6、考慮負載的(de)情況,是(shi)純電(dian)阻性、電(dian)容性還是(shi)電(dian)感性,啟(qi)動(dong)電(dian)流的(de)大小。
太陽能光伏發電系統組成
光伏系統是由太陽(yang)能(neng)電(dian)(dian)池方陣,蓄電(dian)(dian)池組,充放電(dian)(dian)控制(zhi)器,逆變器,交流配(pei)電(dian)(dian)柜、自動(dong)太陽(yang)能(neng)跟蹤系統、自動(dong)太陽(yang)能(neng)組件除(chu)塵系統等設備(bei)組成。其各(ge)部分設備(bei)的(de)作用是:
1、太陽能電池
在(zai)有光(guang)照(zhao)(無論是太陽光(guang),還是其它發光(guang)體產(chan)生(sheng)(sheng)的光(guang)照(zhao))情況下,電(dian)池(chi)(chi)(chi)吸收(shou)光(guang)能(neng)(neng),電(dian)池(chi)(chi)(chi)兩端出現(xian)異號電(dian)荷的積(ji)累,即產(chan)生(sheng)(sheng)“光(guang)生(sheng)(sheng)電(dian)壓”,這就是“光(guang)生(sheng)(sheng)伏特(te)效應(ying)(ying)”。在(zai)光(guang)生(sheng)(sheng)伏特(te)效應(ying)(ying)的作用下,太陽能(neng)(neng)電(dian)池(chi)(chi)(chi)的兩端產(chan)生(sheng)(sheng)電(dian)動勢,將光(guang)能(neng)(neng)轉(zhuan)換成電(dian)能(neng)(neng),是能(neng)(neng)量轉(zhuan)換的器件。太陽能(neng)(neng)電(dian)池(chi)(chi)(chi)一般為硅電(dian)池(chi)(chi)(chi),分為單(dan)晶(jing)硅太陽能(neng)(neng)電(dian)池(chi)(chi)(chi),多(duo)晶(jing)硅太陽能(neng)(neng)電(dian)池(chi)(chi)(chi)和非晶(jing)硅太陽能(neng)(neng)電(dian)池(chi)(chi)(chi)三種。
原材料特點:
電池(chi)片:采用高效率(16.5%以上)的單晶硅太(tai)陽能片封裝,保證太(tai)陽能電池(chi)板發電功率充足。
玻(bo)(bo)(bo)璃:采用低鐵鋼化絨面(mian)玻(bo)(bo)(bo)璃(又(you)稱為(wei)白玻(bo)(bo)(bo)璃),厚度(du)3.2mm,在太陽(yang)電池(chi)光譜響應的波長范圍內(320-1100nm)透(tou)光率達(da)91%以上,對于(yu)大于(yu)1200 nm的紅外光有較高(gao)的反射(she)(she)率。此玻(bo)(bo)(bo)璃同時(shi)能耐太陽(yang)紫(zi)外光線(xian)的輻(fu)射(she)(she),透(tou)光率不下(xia)降。
EVA:采(cai)用加有抗(kang)(kang)紫外劑、抗(kang)(kang)氧化劑和(he)固(gu)化劑的厚度為0.78mm的優質(zhi)EVA膜(mo)層作為太陽電池的密封劑和(he)與玻璃、TPT之(zhi)間的連(lian)接劑。具有較高的透光率和(he)抗(kang)(kang)老化能力。
TPT:太陽(yang)電(dian)(dian)池的(de)(de)背面覆蓋(gai)物—氟塑料(liao)膜為白色(se),對陽(yang)光起反射(she)作(zuo)用,因(yin)此對組件(jian)的(de)(de)效率略有提高,并(bing)因(yin)其具有較高的(de)(de)紅(hong)外發射(she)率,還可降低組件(jian)的(de)(de)工作(zuo)溫(wen)度,也有利于提高組件(jian)的(de)(de)效率。當然,此氟塑料(liao)膜首先具有太陽(yang)電(dian)(dian)池封裝材料(liao)所要求(qiu)的(de)(de)耐老化、耐腐(fu)蝕、不透氣等基本要求(qiu)。
邊(bian)框(kuang):所采用的鋁(lv)合(he)金邊(bian)框(kuang)具有高(gao)強度,抗機械(xie)沖擊能(neng)力強。也是家用太陽能(neng)發(fa)電(dian)中價值(zhi)最高(gao)的部分。
2、蓄電池組
其(qi)作(zuo)用(yong)(yong)(yong)是貯存太(tai)(tai)陽能(neng)電(dian)池(chi)(chi)(chi)(chi)方陣受光照(zhao)時發(fa)(fa)出的(de)電(dian)能(neng)并可(ke)隨時向負(fu)載供電(dian)。太(tai)(tai)陽能(neng)電(dian)池(chi)(chi)(chi)(chi)發(fa)(fa)電(dian)對所用(yong)(yong)(yong)蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi)組的(de)基(ji)本要求是:a.自(zi)放電(dian)率低(di);b.使用(yong)(yong)(yong)壽(shou)命長;c.深放電(dian)能(neng)力強(qiang);d.充(chong)電(dian)效率高(gao);e.少(shao)維護或免維護;f.工(gong)作(zuo)溫度范圍(wei)寬;g.價格(ge)低(di)廉。目前我國與太(tai)(tai)陽能(neng)發(fa)(fa)電(dian)系統(tong)配(pei)套使用(yong)(yong)(yong)的(de)蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi)主要是鉛酸(suan)蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi)和(he)鎘鎳蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi)。配(pei)套200Ah以上的(de)鉛酸(suan)蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi),一般選用(yong)(yong)(yong)固定(ding)式(shi)或工(gong)業(ye)密(mi)封(feng)式(shi)免維護鉛酸(suan)蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi),每只蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi)的(de)額(e)定(ding)電(dian)壓(ya)為(wei)2VDC;配(pei)套200Ah以下的(de)鉛酸(suan)蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi),一般選用(yong)(yong)(yong)小型密(mi)封(feng)免維護鉛酸(suan)蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi),每只蓄(xu)(xu)(xu)電(dian)池(chi)(chi)(chi)(chi)的(de)額(e)定(ding)電(dian)壓(ya)為(wei)12VDC。
3、充放電控制器
是(shi)能自動防止蓄電池過充(chong)(chong)(chong)電和(he)過放電的設備(bei)(bei)。由(you)于蓄電池的循環充(chong)(chong)(chong)放電次數(shu)及(ji)放電深(shen)度是(shi)決定蓄電池使用壽命(ming)的重要因(yin)素,因(yin)此能控(kong)(kong)制蓄電池組(zu)過充(chong)(chong)(chong)電或過放電的充(chong)(chong)(chong)放電控(kong)(kong)制器(qi)是(shi)必不可少的設備(bei)(bei)。
4、逆變器
是(shi)(shi)將直(zhi)(zhi)流(liu)電(dian)轉換成(cheng)交(jiao)流(liu)電(dian)的(de)設備。由于太(tai)陽能(neng)電(dian)池(chi)(chi)和蓄電(dian)池(chi)(chi)是(shi)(shi)直(zhi)(zhi)流(liu)電(dian)源,而負載(zai)(zai)是(shi)(shi)交(jiao)流(liu)負載(zai)(zai)時,逆(ni)(ni)變(bian)器(qi)是(shi)(shi)必不可少的(de)。逆(ni)(ni)變(bian)器(qi)按運(yun)行(xing)方(fang)(fang)式,可分(fen)為獨立(li)運(yun)行(xing)逆(ni)(ni)變(bian)器(qi)和并(bing)網(wang)逆(ni)(ni)變(bian)器(qi)。獨立(li)運(yun)行(xing)逆(ni)(ni)變(bian)器(qi)用于獨立(li)運(yun)行(xing)的(de)太(tai)陽能(neng)電(dian)池(chi)(chi)發電(dian)系統(tong)(tong),為獨立(li)負載(zai)(zai)供電(dian)。并(bing)網(wang)逆(ni)(ni)變(bian)器(qi)用于并(bing)網(wang)運(yun)行(xing)的(de)太(tai)陽能(neng)電(dian)池(chi)(chi)發電(dian)系統(tong)(tong)。逆(ni)(ni)變(bian)器(qi)按輸出波型可分(fen)為方(fang)(fang)波逆(ni)(ni)變(bian)器(qi)和正(zheng)弦(xian)波逆(ni)(ni)變(bian)器(qi)。方(fang)(fang)波逆(ni)(ni)變(bian)器(qi)電(dian)路簡單,造價低,但諧波分(fen)量大,一般用于幾百瓦(wa)以(yi)下和對諧波要求(qiu)不高的(de)系統(tong)(tong)。正(zheng)弦(xian)波逆(ni)(ni)變(bian)器(qi)成(cheng)本高,但可以(yi)適用于各種負載(zai)(zai)。
逆(ni)變器保(bao)(bao)(bao)護(hu)(hu)功能:a、過(guo)載保(bao)(bao)(bao)護(hu)(hu);b、短路保(bao)(bao)(bao)護(hu)(hu);c、接反保(bao)(bao)(bao)護(hu)(hu);d、欠壓保(bao)(bao)(bao)護(hu)(hu);e、過(guo)壓保(bao)(bao)(bao)護(hu)(hu);f、過(guo)熱(re)保(bao)(bao)(bao)護(hu)(hu)。
5、交流配電柜
其(qi)在電(dian)站系(xi)統(tong)的主要作(zuo)用是(shi)對備(bei)用逆(ni)變器(qi)的切換功能(neng),保(bao)證系(xi)統(tong)的正常供電(dian),同(tong)時還有對線路電(dian)能(neng)的計量(liang)。
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