一、光伏發電是什么意思
光伏(fu)發(fa)電(dian)(dian)是(shi)利(li)用半導體界面的光生伏(fu)特效(xiao)應而將光能直(zhi)接轉變為電(dian)(dian)能的一種技術。主要由(you)太陽(yang)電(dian)(dian)池(chi)(chi)板(組(zu)(zu)件(jian)(jian))、控(kong)制(zhi)器和(he)逆變器三大部分組(zu)(zu)成(cheng)(cheng),主要部件(jian)(jian)由(you)電(dian)(dian)子元器件(jian)(jian)構成(cheng)(cheng)。太陽(yang)能電(dian)(dian)池(chi)(chi)經過(guo)串聯后進行封裝(zhuang)(zhuang)保護可形成(cheng)(cheng)大面積(ji)的太陽(yang)電(dian)(dian)池(chi)(chi)組(zu)(zu)件(jian)(jian),再配合上功(gong)率(lv)控(kong)制(zhi)器等部件(jian)(jian)就形成(cheng)(cheng)了光伏(fu)發(fa)電(dian)(dian)裝(zhuang)(zhuang)置。
二、太陽能光伏發電對人體有輻射嗎
光伏(fu)系統有電(dian)磁輻(fu)射,但比較少,采(cai)用(yong)合格(ge)的設備,不會(hui)(hui)對(dui)人體造成傷害和對(dui)家用(yong)電(dian)器(qi)造成干擾。光伏(fu)組件是直(zhi)流電(dian),不會(hui)(hui)產(chan)生輻(fu)射,逆變器(qi)的輻(fu)射嚴(yan)格(ge)控(kong)制在安(an)全范圍內(nei)。
光(guang)伏(fu)發(fa)電(dian)(dian)(dian)(dian)(dian)是(shi)將(jiang)光(guang)能(neng)通過(guo)半導體的(de)(de)特性直(zhi)(zhi)接轉(zhuan)化(hua)為直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)能(neng)的(de)(de),再通過(guo)逆變(bian)器(qi)(qi)將(jiang)直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)轉(zhuan)換成(cheng)可以被我們使用(yong)的(de)(de)交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)。光(guang)伏(fu)系統(tong)是(shi)由光(guang)伏(fu)組(zu)件(jian),支(zhi)架,直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)纜(lan),逆變(bian)器(qi)(qi),交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)纜(lan),配電(dian)(dian)(dian)(dian)(dian)柜(ju),變(bian)壓(ya)器(qi)(qi)等組(zu)成(cheng),其(qi)中支(zhi)架不(bu)帶電(dian)(dian)(dian)(dian)(dian),自然不(bu)會(hui)產(chan)(chan)(chan)生(sheng)電(dian)(dian)(dian)(dian)(dian)磁干擾。光(guang)伏(fu)組(zu)件(jian)和直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)纜(lan),里(li)面(mian)是(shi)直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)流(liu),方(fang)向沒有(you)變(bian)化(hua),只(zhi)能(neng)產(chan)(chan)(chan)生(sheng)電(dian)(dian)(dian)(dian)(dian)場(chang)(chang),不(bu)能(neng)產(chan)(chan)(chan)生(sheng)磁場(chang)(chang)。輸出變(bian)壓(ya)器(qi)(qi)雖然是(shi)交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian),但頻率(lv)很低(di),只(zhi)有(you)50Hz,產(chan)(chan)(chan)生(sheng)的(de)(de)磁場(chang)(chang)很低(di)。逆變(bian)器(qi)(qi)是(shi)把直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)轉(zhuan)為交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)的(de)(de)設備(bei),里(li)面(mian)有(you)電(dian)(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)(dian)子變(bian)換,頻率(lv)一般為5-20KHz,因此會(hui)產(chan)(chan)(chan)生(sheng)交(jiao)變(bian)電(dian)(dian)(dian)(dian)(dian)場(chang)(chang),所以也(ye)會(hui)產(chan)(chan)(chan)生(sheng)電(dian)(dian)(dian)(dian)(dian)磁輻射。但國家對光(guang)伏(fu)逆變(bian)器(qi)(qi)電(dian)(dian)(dian)(dian)(dian)磁兼容(rong)性有(you)嚴格(ge)的(de)(de)標準。光(guang)伏(fu)逆變(bian)器(qi)(qi)的(de)(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,大約和筆記(ji)本電(dian)(dian)(dian)(dian)(dian)腦差不(bu)多(duo),低(di)于電(dian)(dian)(dian)(dian)(dian)磁爐,電(dian)(dian)(dian)(dian)(dian)吹風,冰箱。
因此,太(tai)陽能(neng)光伏發(fa)電不(bu)僅不(bu)會(hui)對人(ren)的健康產(chan)生危(wei)害(hai),還可以為(wei)地球(qiu)提供(gong)綠(lv)色清潔的優質能(neng)源(yuan),是人(ren)類未來能(neng)源(yuan)發(fa)展方向(xiang)。
三、太陽能光伏發電的優點
1、太陽(yang)能資源取之(zhi)不盡(jin),用(yong)(yong)之(zhi)不竭,照射到地(di)(di)球上的(de)太陽(yang)能要比(bi)人類目前消耗的(de)能量大6000倍。而且(qie)太陽(yang)能在地(di)(di)球上分布廣泛(fan),只要有光照的(de)地(di)(di)方就可以(yi)使用(yong)(yong)光伏發電(dian)系統,不受地(di)(di)域(yu)、海(hai)拔等因(yin)素的(de)限制。
2、太陽能資源隨處可(ke)得,可(ke)就近供電,不必長(chang)(chang)距離輸送(song),避免了長(chang)(chang)距離輸電線(xian)路(lu)所造成(cheng)的電能損失。
3、光(guang)伏發(fa)電(dian)(dian)的能量轉(zhuan)換過程簡(jian)單,是直接從光(guang)能到電(dian)(dian)能的轉(zhuan)換,沒(mei)有中間過程(如熱(re)能轉(zhuan)換為(wei)(wei)機(ji)械(xie)(xie)能、機(ji)械(xie)(xie)能轉(zhuan)換為(wei)(wei)電(dian)(dian)磁能等)和機(ji)械(xie)(xie)運動,不(bu)存(cun)在機(ji)械(xie)(xie)磨損。根據(ju)熱(re)力學分析,光(guang)伏發(fa)電(dian)(dian)具有很高的理論發(fa)電(dian)(dian)效率,可達(da)80%以上,技(ji)術(shu)開發(fa)潛力巨大。
4、光伏發電本身不(bu)使用燃料,不(bu)排(pai)放包括溫室氣體和其(qi)它廢(fei)氣在內的(de)任何物(wu)質,不(bu)污染空氣,不(bu)產生(sheng)噪聲,對(dui)環(huan)境友好,不(bu)會遭受能源(yuan)危機或燃料市場(chang)不(bu)穩定而造(zao)成(cheng)的(de)沖擊,是真正綠(lv)色環(huan)保的(de)新型可再生(sheng)能源(yuan)。
5、光伏(fu)(fu)發電過(guo)程不(bu)需要(yao)冷卻水(shui)(shui),可以安裝在沒(mei)有水(shui)(shui)的荒漠戈壁上(shang)。光伏(fu)(fu)發電還(huan)可以很方便(bian)地與建筑物結(jie)合(he),構成光伏(fu)(fu)建筑一體(ti)化發電系統(tong),不(bu)需要(yao)單(dan)獨占地,可節省寶貴的土地資源。
6、光伏(fu)發(fa)電無(wu)機械(xie)傳(chuan)動(dong)部件(jian)(jian),操作、維護(hu)(hu)簡單,運行穩定可靠。一套光伏(fu)發(fa)電系統只(zhi)要有太陽(yang)能(neng)(neng)電池組件(jian)(jian)就能(neng)(neng)發(fa)電,加(jia)之自動(dong)控制技(ji)術的廣泛采用(yong),基(ji)本(ben)上可實現無(wu)人(ren)值守,維護(hu)(hu)成本(ben)低(di)。
7、光(guang)伏(fu)發電(dian)(dian)系(xi)統工作(zuo)性(xing)能(neng)穩定(ding)可靠,使用壽命(ming)長(chang)(chang)(chang)(30年(nian)以上)。晶(jing)體(ti)硅(gui)太(tai)陽(yang)能(neng)電(dian)(dian)池壽命(ming)可長(chang)(chang)(chang)達20~35年(nian)。在(zai)光(guang)伏(fu)發電(dian)(dian)系(xi)統中,只要設計合理(li)、選(xuan)型適當(dang),蓄電(dian)(dian)池的壽命(ming)也(ye)可長(chang)(chang)(chang)達10~15年(nian)。
8、太(tai)陽能電池(chi)組件結構簡單,體積小、重(zhong)量輕,便(bian)于運(yun)輸和安裝。光伏發電系統建(jian)設(she)周期短,而且根據(ju)用電負荷(he)容量可大可小,方便(bian)靈活(huo),極易組合、擴容。
四、太陽能光伏發電的缺點
1、能量密度低
盡管太陽(yang)(yang)投向地(di)(di)球(qiu)(qiu)的能量(liang)總和極(ji)其巨(ju)大(da),但由于地(di)(di)球(qiu)(qiu)表(biao)面積也很大(da),而(er)且地(di)(di)球(qiu)(qiu)表(biao)面大(da)部分被海洋覆(fu)蓋,真正能夠到達(da)陸地(di)(di)表(biao)面的太陽(yang)(yang)能只有到達(da)地(di)(di)球(qiu)(qiu)范(fan)圍(wei)太陽(yang)(yang)輻射能量(liang)的10%左右,致使在陸地(di)(di)單(dan)位(wei)面積上能夠直(zhi)接獲(huo)得的太陽(yang)(yang)能量(liang)較少。通常以太陽(yang)(yang)輻照(zhao)(zhao)度來表(biao)示,地(di)(di)球(qiu)(qiu)表(biao)面輻照(zhao)(zhao)度最高值約為1.2kw/㎡,且絕(jue)大(da)多(duo)數地(di)(di)區(qu)和大(da)多(duo)數日(ri)照(zhao)(zhao)時間內都低于1kw/㎡。太陽(yang)(yang)能的利(li)用(yong)實際上是(shi)低密度能量(liang)的收集、利(li)用(yong)。
2、占地面積大
由(you)于太(tai)陽能(neng)能(neng)量密度低,這就使得光(guang)(guang)伏(fu)發(fa)(fa)(fa)電系統的占(zhan)地面(mian)積(ji)(ji)會很大,每(mei)10kw光(guang)(guang)伏(fu)發(fa)(fa)(fa)電功(gong)率占(zhan)地約(yue)需(xu)100㎡,平均每(mei)平方米面(mian)積(ji)(ji)發(fa)(fa)(fa)電功(gong)率為100w。隨著光(guang)(guang)伏(fu)建筑一體化發(fa)(fa)(fa)電技術的成熟(shu)和發(fa)(fa)(fa)展,越(yue)來越(yue)多的光(guang)(guang)伏(fu)發(fa)(fa)(fa)電系統可以利(li)用建筑物、構筑物的屋頂和立(li)面(mian),將(jiang)逐漸克(ke)服(fu)光(guang)(guang)伏(fu)發(fa)(fa)(fa)電占(zhan)地面(mian)積(ji)(ji)大的不足。
3、轉換效率低
光(guang)(guang)(guang)(guang)伏(fu)(fu)發(fa)(fa)電(dian)(dian)(dian)的最基本單元(yuan)是(shi)太(tai)(tai)陽能(neng)電(dian)(dian)(dian)池(chi)組件。光(guang)(guang)(guang)(guang)伏(fu)(fu)發(fa)(fa)電(dian)(dian)(dian)的轉(zhuan)換(huan)(huan)(huan)效率(lv)指光(guang)(guang)(guang)(guang)能(neng)轉(zhuan)換(huan)(huan)(huan)為(wei)(wei)電(dian)(dian)(dian)能(neng)的比率(lv)。目前晶(jing)體硅(gui)光(guang)(guang)(guang)(guang)伏(fu)(fu)電(dian)(dian)(dian)池(chi)轉(zhuan)換(huan)(huan)(huan)效率(lv)為(wei)(wei)13%~17%,非(fei)晶(jing)硅(gui)光(guang)(guang)(guang)(guang)伏(fu)(fu)電(dian)(dian)(dian)池(chi)只有5%~8%。由于光(guang)(guang)(guang)(guang)電(dian)(dian)(dian)轉(zhuan)換(huan)(huan)(huan)效率(lv)太(tai)(tai)低(di),從而使(shi)光(guang)(guang)(guang)(guang)伏(fu)(fu)發(fa)(fa)電(dian)(dian)(dian)功(gong)率(lv)密度(du)低(di),難以(yi)形成高功(gong)率(lv)發(fa)(fa)電(dian)(dian)(dian)系統(tong)。因此,太(tai)(tai)陽能(neng)電(dian)(dian)(dian)池(chi)的轉(zhuan)換(huan)(huan)(huan)效率(lv)低(di)是(shi)阻礙光(guang)(guang)(guang)(guang)伏(fu)(fu)發(fa)(fa)電(dian)(dian)(dian)大面積推廣的瓶頸(jing)。
4、間歇性工作
在地球表面,光伏發電(dian)系統只能(neng)(neng)在白天(tian)發電(dian),晚(wan)上不(bu)能(neng)(neng)發電(dian),除非在太(tai)空中沒有晝(zhou)夜之分的情況(kuang)下,太(tai)陽(yang)能(neng)(neng)電(dian)池才可以連續發電(dian),這(zhe)與人(ren)們的用電(dian)需求不(bu)符。
5、受氣候環境因素影響大
太(tai)(tai)(tai)陽(yang)(yang)能(neng)光伏發電(dian)的(de)能(neng)源直接來源于(yu)太(tai)(tai)(tai)陽(yang)(yang)光的(de)照(zhao)射,而(er)地球表面(mian)上的(de)太(tai)(tai)(tai)陽(yang)(yang)照(zhao)射受氣候(hou)的(de)影響(xiang)很大,長(chang)期的(de)雨雪天(tian)、陰(yin)天(tian)、霧天(tian)甚至(zhi)云層的(de)變化都會嚴重影響(xiang)系統的(de)發電(dian)狀態。另外,環(huan)境因素的(de)影響(xiang)也(ye)很大,比較突出(chu)的(de)一點是,空(kong)氣中的(de)顆粒物(如灰(hui)塵)等沉落在太(tai)(tai)(tai)陽(yang)(yang)能(neng)電(dian)池組(zu)件(jian)的(de)表面(mian),阻擋了部分(fen)光線的(de)照(zhao)射,這(zhe)樣會使(shi)電(dian)池組(zu)件(jian)轉換(huan)效率降低,從而(er)造成發電(dian)量減少甚至(zhi)電(dian)池板的(de)損壞(huai)。
6、地域依賴性強
地(di)理位置(zhi)不同,氣候不同,使各地(di)區日照資(zi)源(yuan)相差很大。光伏發電系統(tong)只有應(ying)用在(zai)太(tai)陽能資(zi)源(yuan)豐(feng)富的地(di)區,其效果才會好。
7、系統成本高
由于太(tai)陽能(neng)光伏(fu)發(fa)電(dian)(dian)的(de)(de)(de)效率(lv)較(jiao)低,到(dao)目前為止,光伏(fu)發(fa)電(dian)(dian)的(de)(de)(de)成本仍然是(shi)(shi)其(qi)他常規發(fa)電(dian)(dian)方(fang)式(如火力和水(shui)力發(fa)電(dian)(dian))的(de)(de)(de)幾(ji)倍,這是(shi)(shi)制(zhi)約其(qi)廣泛(fan)應用的(de)(de)(de)最主要因素。但是(shi)(shi)也應看到(dao),隨(sui)著太(tai)陽能(neng)電(dian)(dian)池產能(neng)的(de)(de)(de)不斷擴大(da)及(ji)電(dian)(dian)池片光電(dian)(dian)轉換效率(lv)的(de)(de)(de)不斷提高,光伏(fu)發(fa)電(dian)(dian)系統的(de)(de)(de)成本也下降(jiang)得非常快。太(tai)陽能(neng)電(dian)(dian)池組件的(de)(de)(de)價格幾(ji)十年(nian)來已(yi)經(jing)從最初的(de)(de)(de)每(mei)瓦70多(duo)美元(yuan)(yuan)下降(jiang)至(zhi)目前的(de)(de)(de)每(mei)瓦2美元(yuan)(yuan)左右。
8、晶體硅電池的制造過程高污染、高能耗
晶體硅電(dian)池的主要(yao)(yao)原料是(shi)純凈的硅。硅是(shi)地球(qiu)上含量(liang)僅(jin)(jin)次于氧的元素(su),主要(yao)(yao)存在形式是(shi)沙(sha)子(sio2)。從(cong)硅砂(sha)一(yi)步(bu)步(bu)變成純度為(wei)99.9999%以上的晶體硅,要(yao)(yao)經過(guo)多道化學和物(wu)理工序(xu)的處理,不(bu)僅(jin)(jin)要(yao)(yao)消耗(hao)大量(liang)能源,還(huan)會(hui)造(zao)成一(yi)定的環境(jing)污染(ran)。