一、光伏發電是什么意思
光(guang)(guang)伏發(fa)電(dian)(dian)是利(li)用半導體界面(mian)的(de)光(guang)(guang)生伏特效應(ying)而將光(guang)(guang)能直接轉(zhuan)變為電(dian)(dian)能的(de)一種技(ji)術。主(zhu)要(yao)由太陽電(dian)(dian)池(chi)板(組(zu)(zu)件)、控(kong)制器(qi)和逆變器(qi)三大部(bu)分組(zu)(zu)成(cheng)(cheng),主(zhu)要(yao)部(bu)件由電(dian)(dian)子元器(qi)件構成(cheng)(cheng)。太陽能電(dian)(dian)池(chi)經過串聯后進行封裝(zhuang)(zhuang)保護可(ke)形(xing)成(cheng)(cheng)大面(mian)積的(de)太陽電(dian)(dian)池(chi)組(zu)(zu)件,再配合上功率控(kong)制器(qi)等部(bu)件就形(xing)成(cheng)(cheng)了光(guang)(guang)伏發(fa)電(dian)(dian)裝(zhuang)(zhuang)置。
二、太陽能光伏發電對人體有輻射嗎
光(guang)伏(fu)系(xi)統有(you)電磁輻射,但比較少,采用合格(ge)的設備,不(bu)會對(dui)人體造(zao)(zao)成傷害和對(dui)家用電器造(zao)(zao)成干擾。光(guang)伏(fu)組件是直流(liu)電,不(bu)會產生輻射,逆變器的輻射嚴格(ge)控制(zhi)在(zai)安全范(fan)圍內。
光伏(fu)(fu)發電(dian)(dian)(dian)(dian)(dian)是將(jiang)光能通(tong)(tong)過(guo)半(ban)導體的(de)特性直(zhi)接轉化為(wei)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)能的(de),再(zai)通(tong)(tong)過(guo)逆變(bian)(bian)器(qi)(qi)將(jiang)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)轉換(huan)成可以(yi)被我們(men)使用(yong)的(de)交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)。光伏(fu)(fu)系統是由光伏(fu)(fu)組件(jian),支架,直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)纜,逆變(bian)(bian)器(qi)(qi),交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)纜,配電(dian)(dian)(dian)(dian)(dian)柜,變(bian)(bian)壓器(qi)(qi)等(deng)組成,其中支架不帶電(dian)(dian)(dian)(dian)(dian),自然(ran)不會(hui)(hui)(hui)產(chan)生(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)磁干(gan)擾。光伏(fu)(fu)組件(jian)和(he)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)纜,里(li)面(mian)是直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu),方向沒(mei)有(you)變(bian)(bian)化,只(zhi)(zhi)能產(chan)生(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)場(chang),不能產(chan)生(sheng)(sheng)磁場(chang)。輸出變(bian)(bian)壓器(qi)(qi)雖然(ran)是交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian),但頻率很(hen)低,只(zhi)(zhi)有(you)50Hz,產(chan)生(sheng)(sheng)的(de)磁場(chang)很(hen)低。逆變(bian)(bian)器(qi)(qi)是把直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)轉為(wei)交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)的(de)設(she)備,里(li)面(mian)有(you)電(dian)(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)(dian)子變(bian)(bian)換(huan),頻率一般為(wei)5-20KHz,因此(ci)會(hui)(hui)(hui)產(chan)生(sheng)(sheng)交(jiao)變(bian)(bian)電(dian)(dian)(dian)(dian)(dian)場(chang),所以(yi)也(ye)會(hui)(hui)(hui)產(chan)生(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)磁輻射。但國家對光伏(fu)(fu)逆變(bian)(bian)器(qi)(qi)電(dian)(dian)(dian)(dian)(dian)磁兼容(rong)性有(you)嚴(yan)格的(de)標(biao)準。光伏(fu)(fu)逆變(bian)(bian)器(qi)(qi)的(de)電(dian)(dian)(dian)(dian)(dian)磁輻射,同家用(yong)電(dian)(dian)(dian)(dian)(dian)器(qi)(qi)相比,大(da)約和(he)筆記本電(dian)(dian)(dian)(dian)(dian)腦差(cha)不多,低于電(dian)(dian)(dian)(dian)(dian)磁爐,電(dian)(dian)(dian)(dian)(dian)吹(chui)風,冰箱(xiang)。
因(yin)此,太陽能(neng)(neng)光伏(fu)發(fa)電不(bu)僅不(bu)會(hui)對人的(de)健康產生危(wei)害,還(huan)可以為地球提(ti)供(gong)綠色清潔的(de)優質能(neng)(neng)源(yuan),是人類未來能(neng)(neng)源(yuan)發(fa)展方向。
三、太陽能光伏發電的優點
1、太陽能(neng)(neng)資源取之(zhi)不(bu)盡(jin),用(yong)(yong)之(zhi)不(bu)竭,照射到地(di)球(qiu)上的太陽能(neng)(neng)要(yao)比人類目前消耗(hao)的能(neng)(neng)量大6000倍(bei)。而且太陽能(neng)(neng)在地(di)球(qiu)上分布廣泛,只要(yao)有光照的地(di)方(fang)就可(ke)以(yi)使用(yong)(yong)光伏(fu)發電系(xi)統,不(bu)受地(di)域(yu)、海拔等因素的限制。
2、太陽能(neng)(neng)資(zi)源隨處可得(de),可就近供電,不(bu)必長距(ju)離(li)輸(shu)送,避免了長距(ju)離(li)輸(shu)電線路所造成的電能(neng)(neng)損失。
3、光伏(fu)發電的(de)能(neng)量轉(zhuan)換(huan)過(guo)程簡單,是(shi)直接從光能(neng)到(dao)電能(neng)的(de)轉(zhuan)換(huan),沒(mei)有(you)中間過(guo)程(如熱能(neng)轉(zhuan)換(huan)為機(ji)械(xie)能(neng)、機(ji)械(xie)能(neng)轉(zhuan)換(huan)為電磁能(neng)等)和機(ji)械(xie)運(yun)動,不(bu)存在機(ji)械(xie)磨損。根據熱力(li)學分析,光伏(fu)發電具有(you)很高的(de)理論發電效率,可達80%以上,技術開發潛力(li)巨大。
4、光伏發電本身不(bu)使用燃(ran)料,不(bu)排放包括溫室氣體和(he)其它(ta)廢氣在內的(de)任(ren)何物質(zhi),不(bu)污染空(kong)氣,不(bu)產生(sheng)噪聲(sheng),對(dui)環(huan)境友(you)好,不(bu)會遭(zao)受能源(yuan)危機或燃(ran)料市場(chang)不(bu)穩定而造成的(de)沖擊,是真正綠色環(huan)保(bao)的(de)新型(xing)可再生(sheng)能源(yuan)。
5、光伏發電過(guo)程不需(xu)要冷卻水,可以安(an)裝在(zai)沒有水的荒漠戈壁(bi)上。光伏發電還可以很方便(bian)地與(yu)建筑物結合,構(gou)成光伏建筑一體(ti)化(hua)發電系統,不需(xu)要單獨(du)占地,可節省寶(bao)貴的土(tu)地資(zi)源。
6、光伏(fu)發電(dian)(dian)無機械傳(chuan)動(dong)部件,操作(zuo)、維護(hu)簡單(dan),運行穩(wen)定可靠。一套光伏(fu)發電(dian)(dian)系(xi)統只要(yao)有太陽能(neng)電(dian)(dian)池組(zu)件就能(neng)發電(dian)(dian),加(jia)之自動(dong)控制技術的廣泛采用,基本上可實現無人值守,維護(hu)成本低。
7、光伏(fu)發(fa)電(dian)(dian)系統(tong)工作(zuo)性能穩定可(ke)靠,使用壽命長(30年以(yi)上)。晶體硅太陽能電(dian)(dian)池(chi)壽命可(ke)長達20~35年。在光伏(fu)發(fa)電(dian)(dian)系統(tong)中(zhong),只要設計(ji)合理(li)、選(xuan)型(xing)適當(dang),蓄電(dian)(dian)池(chi)的壽命也可(ke)長達10~15年。
8、太陽能電池組(zu)件結構簡單,體積小、重量輕,便(bian)(bian)于運輸和安裝。光伏發電系(xi)統建(jian)設周期短,而且根(gen)據用電負荷容量可大可小,方便(bian)(bian)靈活,極(ji)易組(zu)合(he)、擴容。
四、太陽能光伏發電的缺點
1、能量密度低
盡管(guan)太(tai)陽(yang)投向地(di)(di)(di)球(qiu)的(de)能(neng)(neng)量(liang)總和極(ji)其巨(ju)大,但由(you)于地(di)(di)(di)球(qiu)表(biao)(biao)面(mian)積也很大,而且地(di)(di)(di)球(qiu)表(biao)(biao)面(mian)大部分被海(hai)洋(yang)覆蓋(gai),真正能(neng)(neng)夠到達陸地(di)(di)(di)表(biao)(biao)面(mian)的(de)太(tai)陽(yang)能(neng)(neng)只有到達地(di)(di)(di)球(qiu)范圍太(tai)陽(yang)輻射(she)能(neng)(neng)量(liang)的(de)10%左右,致使在陸地(di)(di)(di)單(dan)位面(mian)積上(shang)能(neng)(neng)夠直接獲得的(de)太(tai)陽(yang)能(neng)(neng)量(liang)較少。通常以太(tai)陽(yang)輻照(zhao)(zhao)度來表(biao)(biao)示,地(di)(di)(di)球(qiu)表(biao)(biao)面(mian)輻照(zhao)(zhao)度最高值約為1.2kw/㎡,且絕大多數地(di)(di)(di)區和大多數日(ri)照(zhao)(zhao)時(shi)間內都低于1kw/㎡。太(tai)陽(yang)能(neng)(neng)的(de)利用實(shi)際(ji)上(shang)是低密度能(neng)(neng)量(liang)的(de)收集、利用。
2、占地面積大
由于(yu)太陽能(neng)能(neng)量密度低(di),這就使(shi)得光(guang)(guang)伏(fu)發(fa)(fa)電(dian)系統(tong)的(de)占(zhan)地(di)(di)面(mian)(mian)積會很(hen)大(da),每10kw光(guang)(guang)伏(fu)發(fa)(fa)電(dian)功(gong)率占(zhan)地(di)(di)約需100㎡,平均每平方(fang)米面(mian)(mian)積發(fa)(fa)電(dian)功(gong)率為(wei)100w。隨著光(guang)(guang)伏(fu)建筑(zhu)一體化發(fa)(fa)電(dian)技術的(de)成熟和發(fa)(fa)展,越來(lai)越多的(de)光(guang)(guang)伏(fu)發(fa)(fa)電(dian)系統(tong)可以利用建筑(zhu)物、構筑(zhu)物的(de)屋頂和立面(mian)(mian),將(jiang)逐(zhu)漸克服光(guang)(guang)伏(fu)發(fa)(fa)電(dian)占(zhan)地(di)(di)面(mian)(mian)積大(da)的(de)不足。
3、轉換效率低
光(guang)伏發(fa)(fa)(fa)電(dian)(dian)(dian)(dian)的(de)(de)最基本(ben)單元(yuan)是(shi)太(tai)(tai)(tai)陽(yang)能電(dian)(dian)(dian)(dian)池組件。光(guang)伏發(fa)(fa)(fa)電(dian)(dian)(dian)(dian)的(de)(de)轉(zhuan)(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)指光(guang)能轉(zhuan)(zhuan)換(huan)(huan)為電(dian)(dian)(dian)(dian)能的(de)(de)比率(lv)(lv)。目(mu)前(qian)晶體硅光(guang)伏電(dian)(dian)(dian)(dian)池轉(zhuan)(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)為13%~17%,非晶硅光(guang)伏電(dian)(dian)(dian)(dian)池只(zhi)有5%~8%。由于光(guang)電(dian)(dian)(dian)(dian)轉(zhuan)(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)太(tai)(tai)(tai)低,從而使光(guang)伏發(fa)(fa)(fa)電(dian)(dian)(dian)(dian)功(gong)率(lv)(lv)密(mi)度低,難以形成高(gao)功(gong)率(lv)(lv)發(fa)(fa)(fa)電(dian)(dian)(dian)(dian)系統(tong)。因此(ci),太(tai)(tai)(tai)陽(yang)能電(dian)(dian)(dian)(dian)池的(de)(de)轉(zhuan)(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)低是(shi)阻礙光(guang)伏發(fa)(fa)(fa)電(dian)(dian)(dian)(dian)大面積推廣的(de)(de)瓶頸(jing)。
4、間歇性工作
在(zai)地球表面,光伏發電(dian)系統只能在(zai)白天(tian)發電(dian),晚上不(bu)能發電(dian),除非在(zai)太(tai)空中沒有晝(zhou)夜之分的情況下(xia),太(tai)陽能電(dian)池(chi)才可以連續發電(dian),這(zhe)與人們的用電(dian)需求(qiu)不(bu)符。
5、受氣候環境因素影響大
太(tai)(tai)陽(yang)能光(guang)伏發電的(de)(de)能源(yuan)(yuan)直接來(lai)源(yuan)(yuan)于太(tai)(tai)陽(yang)光(guang)的(de)(de)照射,而地球表(biao)面(mian)上的(de)(de)太(tai)(tai)陽(yang)照射受氣候(hou)的(de)(de)影響很大(da),長(chang)期的(de)(de)雨(yu)雪天、陰(yin)天、霧(wu)天甚至(zhi)云層的(de)(de)變化都會嚴重影響系統的(de)(de)發電狀態(tai)。另外(wai),環境因素的(de)(de)影響也很大(da),比較突出的(de)(de)一點是,空氣中的(de)(de)顆(ke)粒物(如灰塵)等沉落在(zai)太(tai)(tai)陽(yang)能電池(chi)組件的(de)(de)表(biao)面(mian),阻擋了(le)部分光(guang)線的(de)(de)照射,這樣(yang)會使電池(chi)組件轉(zhuan)換效率(lv)降低,從而造成發電量減少甚至(zhi)電池(chi)板的(de)(de)損壞。
6、地域依賴性強
地(di)理位(wei)置不(bu)同,氣候不(bu)同,使各地(di)區(qu)日照資源相差很大。光伏發電(dian)系(xi)統只(zhi)有(you)應(ying)用(yong)在(zai)太陽能資源豐富的地(di)區(qu),其效果才會好。
7、系統成本高
由于太陽(yang)(yang)能(neng)(neng)光伏發電(dian)(dian)(dian)的(de)(de)效率較低,到目前為(wei)止,光伏發電(dian)(dian)(dian)的(de)(de)成本(ben)仍然是(shi)其他常規發電(dian)(dian)(dian)方式(shi)(如火(huo)力和水力發電(dian)(dian)(dian))的(de)(de)幾(ji)倍,這是(shi)制約(yue)其廣泛應用的(de)(de)最主要因素。但是(shi)也應看到,隨著(zhu)太陽(yang)(yang)能(neng)(neng)電(dian)(dian)(dian)池產(chan)能(neng)(neng)的(de)(de)不(bu)斷擴大(da)及電(dian)(dian)(dian)池片光電(dian)(dian)(dian)轉換效率的(de)(de)不(bu)斷提高,光伏發電(dian)(dian)(dian)系統(tong)的(de)(de)成本(ben)也下降得(de)非常快。太陽(yang)(yang)能(neng)(neng)電(dian)(dian)(dian)池組件的(de)(de)價(jia)格幾(ji)十年來已經從最初的(de)(de)每(mei)(mei)瓦(wa)70多(duo)美(mei)元下降至目前的(de)(de)每(mei)(mei)瓦(wa)2美(mei)元左右。
8、晶體硅電池的制造過程高污染、高能耗
晶(jing)體硅電(dian)池的(de)主要(yao)(yao)原料是純凈(jing)的(de)硅。硅是地球上(shang)含量僅次(ci)于氧的(de)元素,主要(yao)(yao)存在(zai)形式是沙子(sio2)。從硅砂一步(bu)步(bu)變成(cheng)純度為99.9999%以上(shang)的(de)晶(jing)體硅,要(yao)(yao)經(jing)過多道(dao)化學(xue)和物理工序的(de)處理,不僅要(yao)(yao)消耗大量能源,還(huan)會造成(cheng)一定的(de)環(huan)境污染(ran)。