一、光伏發電是什么意思
光伏(fu)發電(dian)(dian)是(shi)利用(yong)半導體界面的光生伏(fu)特效應(ying)而將光能(neng)直接轉變為電(dian)(dian)能(neng)的一種(zhong)技術(shu)。主(zhu)(zhu)要由太陽(yang)電(dian)(dian)池板(組件(jian)(jian))、控制器(qi)和逆變器(qi)三大(da)部分組成,主(zhu)(zhu)要部件(jian)(jian)由電(dian)(dian)子元器(qi)件(jian)(jian)構成。太陽(yang)能(neng)電(dian)(dian)池經過(guo)串聯(lian)后進(jin)行封(feng)裝(zhuang)保(bao)護可形(xing)成大(da)面積的太陽(yang)電(dian)(dian)池組件(jian)(jian),再配合上功率控制器(qi)等(deng)部件(jian)(jian)就形(xing)成了光伏(fu)發電(dian)(dian)裝(zhuang)置。
二、太陽能光伏發電對人體有輻射嗎
光(guang)伏(fu)(fu)系統有(you)電磁輻射,但比較(jiao)少,采用合格的(de)設備,不會對人(ren)體(ti)造(zao)成傷害和對家用電器(qi)造(zao)成干擾。光(guang)伏(fu)(fu)組(zu)件是直流電,不會產生輻射,逆變器(qi)的(de)輻射嚴格控制在安全(quan)范圍內。
光伏(fu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)是(shi)(shi)將(jiang)光能(neng)通過(guo)半導體(ti)的(de)(de)(de)(de)特性(xing)直(zhi)接轉化為直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能(neng)的(de)(de)(de)(de),再通過(guo)逆(ni)變(bian)器(qi)將(jiang)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)轉換成可以被我們(men)使用(yong)的(de)(de)(de)(de)交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。光伏(fu)系(xi)統是(shi)(shi)由光伏(fu)組(zu)(zu)件,支(zhi)架,直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜,逆(ni)變(bian)器(qi),交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜,配電(dian)(dian)(dian)(dian)(dian)(dian)(dian)柜,變(bian)壓(ya)(ya)器(qi)等組(zu)(zu)成,其中支(zhi)架不(bu)(bu)帶電(dian)(dian)(dian)(dian)(dian)(dian)(dian),自(zi)然不(bu)(bu)會產生電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁干(gan)擾。光伏(fu)組(zu)(zu)件和直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜,里面是(shi)(shi)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu),方向沒有(you)(you)變(bian)化,只能(neng)產生電(dian)(dian)(dian)(dian)(dian)(dian)(dian)場,不(bu)(bu)能(neng)產生磁場。輸出變(bian)壓(ya)(ya)器(qi)雖然是(shi)(shi)交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian),但頻率很低(di),只有(you)(you)50Hz,產生的(de)(de)(de)(de)磁場很低(di)。逆(ni)變(bian)器(qi)是(shi)(shi)把直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)轉為交(jiao)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)設備,里面有(you)(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)(dian)(dian)(dian)子變(bian)換,頻率一般為5-20KHz,因(yin)此會產生交(jiao)變(bian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)場,所以也會產生電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁輻射。但國家對光伏(fu)逆(ni)變(bian)器(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁兼容性(xing)有(you)(you)嚴格的(de)(de)(de)(de)標(biao)準。光伏(fu)逆(ni)變(bian)器(qi)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁輻射,同家用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)相比,大約(yue)和筆(bi)記本電(dian)(dian)(dian)(dian)(dian)(dian)(dian)腦(nao)差(cha)不(bu)(bu)多,低(di)于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁爐,電(dian)(dian)(dian)(dian)(dian)(dian)(dian)吹風,冰箱。
因此(ci),太陽能(neng)(neng)光伏發(fa)電不(bu)僅不(bu)會(hui)對人(ren)的健康(kang)產生(sheng)危害,還可以為地球(qiu)提供(gong)綠色清潔的優(you)質能(neng)(neng)源,是(shi)人(ren)類未(wei)來能(neng)(neng)源發(fa)展方向。
三、太陽能光伏發電的優點
1、太陽(yang)(yang)能資源(yuan)取之不盡,用之不竭(jie),照射到(dao)地(di)球(qiu)上的(de)太陽(yang)(yang)能要比人(ren)類目前消耗(hao)的(de)能量(liang)大(da)6000倍(bei)。而且太陽(yang)(yang)能在地(di)球(qiu)上分布廣泛,只要有光照的(de)地(di)方就(jiu)可以使用光伏發電(dian)系統(tong),不受地(di)域、海拔等因素的(de)限(xian)制。
2、太陽(yang)能資源隨處可得,可就(jiu)近供電(dian),不必長距離(li)輸送,避(bi)免了長距離(li)輸電(dian)線路所造成的電(dian)能損失。
3、光伏發(fa)電(dian)的能(neng)量轉換(huan)過(guo)程(cheng)簡單(dan),是直接(jie)從光能(neng)到電(dian)能(neng)的轉換(huan),沒有中間(jian)過(guo)程(cheng)(如熱(re)能(neng)轉換(huan)為(wei)機(ji)(ji)械(xie)(xie)(xie)能(neng)、機(ji)(ji)械(xie)(xie)(xie)能(neng)轉換(huan)為(wei)電(dian)磁能(neng)等)和(he)機(ji)(ji)械(xie)(xie)(xie)運(yun)動,不存在機(ji)(ji)械(xie)(xie)(xie)磨損。根據熱(re)力(li)學分析,光伏發(fa)電(dian)具有很高的理論發(fa)電(dian)效率,可達80%以上(shang),技術(shu)開(kai)發(fa)潛力(li)巨大。
4、光伏發電本身不(bu)(bu)使用(yong)燃(ran)料(liao),不(bu)(bu)排放包(bao)括溫(wen)室氣(qi)體和其它廢氣(qi)在內的(de)任何物質,不(bu)(bu)污染(ran)空(kong)氣(qi),不(bu)(bu)產生噪聲,對環境友(you)好,不(bu)(bu)會遭(zao)受能源危(wei)機或燃(ran)料(liao)市場不(bu)(bu)穩(wen)定而造成的(de)沖擊,是真正綠色環保的(de)新型(xing)可再(zai)生能源。
5、光伏(fu)(fu)發(fa)電過程不需(xu)(xu)要(yao)冷卻水,可(ke)以(yi)安裝在沒有水的荒漠戈壁上。光伏(fu)(fu)發(fa)電還可(ke)以(yi)很方便地與建(jian)筑(zhu)物結(jie)合,構成(cheng)光伏(fu)(fu)建(jian)筑(zhu)一(yi)體化(hua)發(fa)電系統,不需(xu)(xu)要(yao)單獨占地,可(ke)節省(sheng)寶(bao)貴的土地資(zi)源。
6、光(guang)伏(fu)發電無機械傳(chuan)動部(bu)件,操作(zuo)、維護簡(jian)單,運行穩定可(ke)(ke)靠(kao)。一(yi)套光(guang)伏(fu)發電系統只要有(you)太陽能(neng)電池組件就能(neng)發電,加之自(zi)動控制技術的廣泛采(cai)用,基本(ben)上(shang)可(ke)(ke)實(shi)現無人值守,維護成本(ben)低。
7、光伏(fu)發(fa)電系(xi)統工作性(xing)能(neng)穩(wen)定可靠,使(shi)用壽(shou)命長(30年以上)。晶(jing)體硅太陽能(neng)電池(chi)壽(shou)命可長達(da)20~35年。在光伏(fu)發(fa)電系(xi)統中,只要(yao)設計合理(li)、選(xuan)型(xing)適當,蓄電池(chi)的壽(shou)命也(ye)可長達(da)10~15年。
8、太陽(yang)能電池(chi)組件結構(gou)簡單,體積小、重量輕,便于運(yun)輸(shu)和安裝。光(guang)伏發電系統建設周期短,而且根據(ju)用電負荷容(rong)量可大(da)可小,方便靈活,極易組合、擴(kuo)容(rong)。
四、太陽能光伏發電的缺點
1、能量密度低
盡管(guan)太(tai)(tai)(tai)陽(yang)投向地(di)球的(de)(de)能量(liang)(liang)總和(he)極其(qi)巨(ju)大,但由于(yu)(yu)地(di)球表(biao)(biao)面(mian)(mian)積(ji)也很大,而且地(di)球表(biao)(biao)面(mian)(mian)大部分被海洋覆蓋,真正能夠到(dao)達陸地(di)表(biao)(biao)面(mian)(mian)的(de)(de)太(tai)(tai)(tai)陽(yang)能只有到(dao)達地(di)球范圍太(tai)(tai)(tai)陽(yang)輻射能量(liang)(liang)的(de)(de)10%左(zuo)右(you),致(zhi)使在陸地(di)單位面(mian)(mian)積(ji)上能夠直接獲得(de)的(de)(de)太(tai)(tai)(tai)陽(yang)能量(liang)(liang)較少。通常以太(tai)(tai)(tai)陽(yang)輻照(zhao)度(du)來表(biao)(biao)示(shi),地(di)球表(biao)(biao)面(mian)(mian)輻照(zhao)度(du)最高值約為1.2kw/㎡,且絕大多數地(di)區和(he)大多數日照(zhao)時間內都低于(yu)(yu)1kw/㎡。太(tai)(tai)(tai)陽(yang)能的(de)(de)利(li)用(yong)(yong)實際上是低密度(du)能量(liang)(liang)的(de)(de)收集、利(li)用(yong)(yong)。
2、占地面積大
由于太陽(yang)能(neng)能(neng)量密度低,這(zhe)就(jiu)使得光(guang)(guang)伏(fu)(fu)(fu)發(fa)(fa)電(dian)(dian)系(xi)統的占地(di)面(mian)(mian)(mian)積會很(hen)大,每10kw光(guang)(guang)伏(fu)(fu)(fu)發(fa)(fa)電(dian)(dian)功(gong)率占地(di)約需100㎡,平均每平方(fang)米面(mian)(mian)(mian)積發(fa)(fa)電(dian)(dian)功(gong)率為100w。隨(sui)著光(guang)(guang)伏(fu)(fu)(fu)建(jian)筑一體(ti)化發(fa)(fa)電(dian)(dian)技術的成熟和(he)發(fa)(fa)展(zhan),越來越多(duo)的光(guang)(guang)伏(fu)(fu)(fu)發(fa)(fa)電(dian)(dian)系(xi)統可(ke)以利用建(jian)筑物(wu)、構筑物(wu)的屋頂和(he)立面(mian)(mian)(mian),將逐漸克服光(guang)(guang)伏(fu)(fu)(fu)發(fa)(fa)電(dian)(dian)占地(di)面(mian)(mian)(mian)積大的不足。
3、轉換效率低
光(guang)伏發(fa)(fa)電(dian)(dian)(dian)的(de)最基本單(dan)元(yuan)是(shi)太(tai)陽能(neng)電(dian)(dian)(dian)池組件。光(guang)伏發(fa)(fa)電(dian)(dian)(dian)的(de)轉(zhuan)換效率指光(guang)能(neng)轉(zhuan)換為(wei)(wei)電(dian)(dian)(dian)能(neng)的(de)比率。目前(qian)晶體硅光(guang)伏電(dian)(dian)(dian)池轉(zhuan)換效率為(wei)(wei)13%~17%,非晶硅光(guang)伏電(dian)(dian)(dian)池只有(you)5%~8%。由(you)于光(guang)電(dian)(dian)(dian)轉(zhuan)換效率太(tai)低,從(cong)而使光(guang)伏發(fa)(fa)電(dian)(dian)(dian)功(gong)率密(mi)度低,難以形(xing)成高功(gong)率發(fa)(fa)電(dian)(dian)(dian)系(xi)統(tong)。因(yin)此(ci),太(tai)陽能(neng)電(dian)(dian)(dian)池的(de)轉(zhuan)換效率低是(shi)阻礙光(guang)伏發(fa)(fa)電(dian)(dian)(dian)大面積推廣的(de)瓶(ping)頸。
4、間歇性工作
在(zai)地球表面,光伏發(fa)電(dian)系(xi)統只能(neng)在(zai)白天(tian)發(fa)電(dian),晚上不能(neng)發(fa)電(dian),除非(fei)在(zai)太空中沒有晝夜之分的情況下,太陽能(neng)電(dian)池(chi)才可以(yi)連續發(fa)電(dian),這(zhe)與人們的用電(dian)需求不符。
5、受氣候環境因素影響大
太陽(yang)能光伏(fu)發電(dian)(dian)(dian)的(de)能源直(zhi)接來源于太陽(yang)光的(de)照(zhao)(zhao)射,而(er)地球表面上的(de)太陽(yang)照(zhao)(zhao)射受氣候的(de)影(ying)響很大,長(chang)期的(de)雨雪天、陰天、霧天甚至(zhi)云層的(de)變化都會(hui)嚴(yan)重影(ying)響系統(tong)的(de)發電(dian)(dian)(dian)狀態。另外,環境因素(su)的(de)影(ying)響也(ye)很大,比較突(tu)出的(de)一點是(shi),空氣中的(de)顆粒物(如灰塵)等(deng)沉落在太陽(yang)能電(dian)(dian)(dian)池(chi)組件(jian)(jian)的(de)表面,阻擋了部分光線(xian)的(de)照(zhao)(zhao)射,這樣會(hui)使(shi)電(dian)(dian)(dian)池(chi)組件(jian)(jian)轉換(huan)效(xiao)率降低,從而(er)造成發電(dian)(dian)(dian)量(liang)減少(shao)甚至(zhi)電(dian)(dian)(dian)池(chi)板的(de)損壞。
6、地域依賴性強
地理位置不(bu)(bu)同,氣候不(bu)(bu)同,使各地區日照資源相差很(hen)大。光伏發(fa)電系統只有應(ying)用在太陽能資源豐(feng)富的地區,其效果才會好。
7、系統成本高
由于太(tai)陽能光伏發(fa)(fa)(fa)電的(de)(de)(de)效率較(jiao)低(di),到目前為止,光伏發(fa)(fa)(fa)電的(de)(de)(de)成(cheng)本(ben)仍然是其(qi)他常規發(fa)(fa)(fa)電方式(如火力(li)和水力(li)發(fa)(fa)(fa)電)的(de)(de)(de)幾倍,這是制(zhi)約其(qi)廣泛應用的(de)(de)(de)最(zui)主要因素。但是也(ye)應看到,隨著太(tai)陽能電池(chi)產能的(de)(de)(de)不斷(duan)擴大及電池(chi)片光電轉換(huan)效率的(de)(de)(de)不斷(duan)提高,光伏發(fa)(fa)(fa)電系(xi)統的(de)(de)(de)成(cheng)本(ben)也(ye)下降(jiang)得非常快。太(tai)陽能電池(chi)組(zu)件的(de)(de)(de)價(jia)格幾十年來已經從最(zui)初的(de)(de)(de)每瓦70多美元下降(jiang)至(zhi)目前的(de)(de)(de)每瓦2美元左右。
8、晶體硅電池的制造過程高污染、高能耗
晶(jing)體(ti)硅(gui)(gui)電池的主要(yao)原料是純(chun)凈(jing)的硅(gui)(gui)。硅(gui)(gui)是地(di)球上(shang)含量僅次于氧的元素(su),主要(yao)存在形式是沙(sha)子(sio2)。從硅(gui)(gui)砂一(yi)步步變成(cheng)純(chun)度(du)為(wei)99.9999%以上(shang)的晶(jing)體(ti)硅(gui)(gui),要(yao)經過多道化(hua)學和物理工(gong)序的處理,不僅要(yao)消耗大量能源,還會造成(cheng)一(yi)定的環(huan)境污染(ran)。