一、光伏發電是什么意思
光(guang)伏(fu)發電(dian)(dian)是(shi)利用半導體界面(mian)的(de)光(guang)生伏(fu)特效應(ying)而將光(guang)能直接(jie)轉變(bian)為電(dian)(dian)能的(de)一種技術。主(zhu)要由(you)太(tai)陽電(dian)(dian)池(chi)板(組件(jian))、控制(zhi)(zhi)器和逆變(bian)器三(san)大部(bu)(bu)(bu)分組成(cheng),主(zhu)要部(bu)(bu)(bu)件(jian)由(you)電(dian)(dian)子元器件(jian)構成(cheng)。太(tai)陽能電(dian)(dian)池(chi)經過串聯后(hou)進行封裝(zhuang)保護(hu)可形成(cheng)大面(mian)積的(de)太(tai)陽電(dian)(dian)池(chi)組件(jian),再配合上功率控制(zhi)(zhi)器等部(bu)(bu)(bu)件(jian)就形成(cheng)了光(guang)伏(fu)發電(dian)(dian)裝(zhuang)置(zhi)。
二、太陽能光伏發電對人體有輻射嗎
光(guang)伏系統有電磁輻射(she),但比較(jiao)少,采用合格(ge)的(de)設備(bei),不會(hui)對人體(ti)造成傷害(hai)和(he)對家用電器造成干擾。光(guang)伏組件是直流電,不會(hui)產生(sheng)輻射(she),逆變(bian)器的(de)輻射(she)嚴(yan)格(ge)控制在安全范圍內。
光(guang)(guang)伏(fu)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)是(shi)(shi)(shi)將光(guang)(guang)能通(tong)過(guo)半(ban)導(dao)體(ti)的(de)(de)特性直(zhi)(zhi)接轉化為直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)能的(de)(de),再通(tong)過(guo)逆(ni)(ni)變器(qi)將直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)轉換成可(ke)以被我(wo)們使用的(de)(de)交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)。光(guang)(guang)伏(fu)系統是(shi)(shi)(shi)由(you)光(guang)(guang)伏(fu)組(zu)件,支(zhi)架,直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan),逆(ni)(ni)變器(qi),交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan),配電(dian)(dian)(dian)(dian)(dian)(dian)柜,變壓(ya)(ya)器(qi)等組(zu)成,其中支(zhi)架不(bu)帶電(dian)(dian)(dian)(dian)(dian)(dian),自然(ran)不(bu)會(hui)產生(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)干擾(rao)。光(guang)(guang)伏(fu)組(zu)件和直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan),里面(mian)是(shi)(shi)(shi)直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu),方向沒有變化,只能產生(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)場(chang)(chang),不(bu)能產生(sheng)(sheng)(sheng)磁(ci)(ci)場(chang)(chang)。輸出變壓(ya)(ya)器(qi)雖然(ran)是(shi)(shi)(shi)交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian),但(dan)頻率很低(di),只有50Hz,產生(sheng)(sheng)(sheng)的(de)(de)磁(ci)(ci)場(chang)(chang)很低(di)。逆(ni)(ni)變器(qi)是(shi)(shi)(shi)把直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)轉為交(jiao)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)設(she)備(bei),里面(mian)有電(dian)(dian)(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)(dian)(dian)子變換,頻率一般為5-20KHz,因此會(hui)產生(sheng)(sheng)(sheng)交(jiao)變電(dian)(dian)(dian)(dian)(dian)(dian)場(chang)(chang),所(suo)以也會(hui)產生(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)輻(fu)射。但(dan)國家對光(guang)(guang)伏(fu)逆(ni)(ni)變器(qi)電(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)兼容性有嚴(yan)格的(de)(de)標準(zhun)。光(guang)(guang)伏(fu)逆(ni)(ni)變器(qi)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)輻(fu)射,同家用電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)相比,大約(yue)和筆記本電(dian)(dian)(dian)(dian)(dian)(dian)腦(nao)差不(bu)多,低(di)于電(dian)(dian)(dian)(dian)(dian)(dian)磁(ci)(ci)爐,電(dian)(dian)(dian)(dian)(dian)(dian)吹風,冰箱(xiang)。
因(yin)此,太(tai)陽(yang)能光伏發(fa)電不(bu)僅(jin)不(bu)會對人的健康產(chan)生危(wei)害,還可以為地(di)球(qiu)提供綠(lv)色清潔的優質能源(yuan)(yuan),是人類未(wei)來能源(yuan)(yuan)發(fa)展方向。
三、太陽能光伏發電的優點
1、太(tai)陽能(neng)資源取之不(bu)盡,用之不(bu)竭,照(zhao)射到地球上(shang)的太(tai)陽能(neng)要比人類目前消耗的能(neng)量大6000倍。而(er)且太(tai)陽能(neng)在(zai)地球上(shang)分(fen)布廣泛(fan),只要有光照(zhao)的地方就可以(yi)使用光伏發電系統,不(bu)受(shou)地域、海拔等因素(su)的限制。
2、太(tai)陽能(neng)(neng)資(zi)源(yuan)隨處(chu)可得(de),可就近供電(dian),不必長距離輸(shu)(shu)送(song),避免了(le)長距離輸(shu)(shu)電(dian)線路所造成的(de)電(dian)能(neng)(neng)損失。
3、光(guang)(guang)伏發(fa)(fa)電的(de)能(neng)量(liang)轉換過程簡單,是(shi)直(zhi)接從光(guang)(guang)能(neng)到電能(neng)的(de)轉換,沒有(you)中間過程(如熱能(neng)轉換為(wei)機(ji)械(xie)能(neng)、機(ji)械(xie)能(neng)轉換為(wei)電磁能(neng)等)和機(ji)械(xie)運(yun)動,不存在機(ji)械(xie)磨損。根(gen)據熱力學(xue)分析,光(guang)(guang)伏發(fa)(fa)電具有(you)很(hen)高的(de)理論發(fa)(fa)電效率,可達80%以上,技術開發(fa)(fa)潛力巨大。
4、光伏發電本身不(bu)(bu)使(shi)用燃(ran)料,不(bu)(bu)排(pai)放包括溫(wen)室氣(qi)體和其它廢氣(qi)在內的(de)任何物質,不(bu)(bu)污染空(kong)氣(qi),不(bu)(bu)產生(sheng)噪聲(sheng),對環(huan)境友(you)好,不(bu)(bu)會遭(zao)受能源危機或燃(ran)料市場不(bu)(bu)穩(wen)定而造成(cheng)的(de)沖擊,是真正綠色環(huan)保的(de)新型可再生(sheng)能源。
5、光(guang)(guang)伏發(fa)(fa)電過程不需要(yao)冷(leng)卻(que)水,可以安裝在沒有水的荒漠戈(ge)壁上。光(guang)(guang)伏發(fa)(fa)電還(huan)可以很方便地與建筑(zhu)物(wu)結合,構成光(guang)(guang)伏建筑(zhu)一(yi)體化發(fa)(fa)電系統(tong),不需要(yao)單獨占地,可節省寶貴的土地資源。
6、光伏(fu)發(fa)電無(wu)機械(xie)傳動(dong)部(bu)件,操作、維(wei)護簡單,運行穩定可靠。一套光伏(fu)發(fa)電系(xi)統只(zhi)要有(you)太陽能(neng)電池組件就能(neng)發(fa)電,加之自動(dong)控(kong)制(zhi)技術的(de)廣(guang)泛采用,基本上可實現無(wu)人值守,維(wei)護成本低。
7、光伏(fu)發電(dian)系(xi)統工(gong)作性(xing)能穩定可靠,使用壽命(ming)(ming)長(30年(nian)以上(shang))。晶體(ti)硅太陽能電(dian)池壽命(ming)(ming)可長達20~35年(nian)。在光伏(fu)發電(dian)系(xi)統中,只(zhi)要設計(ji)合理、選型適當,蓄電(dian)池的壽命(ming)(ming)也可長達10~15年(nian)。
8、太陽能電池組(zu)件結(jie)構簡單,體(ti)積小(xiao)、重量輕,便(bian)于運輸和安裝。光伏發電系統建設周(zhou)期短,而且根據用電負荷容量可大可小(xiao),方便(bian)靈活(huo),極(ji)易組(zu)合、擴容。
四、太陽能光伏發電的缺點
1、能量密度低
盡管太(tai)陽(yang)(yang)投向(xiang)地(di)球(qiu)(qiu)的(de)能(neng)(neng)量總和極其(qi)巨(ju)大(da),但由(you)于地(di)球(qiu)(qiu)表(biao)(biao)(biao)(biao)面(mian)(mian)(mian)(mian)積(ji)也很大(da),而(er)且地(di)球(qiu)(qiu)表(biao)(biao)(biao)(biao)面(mian)(mian)(mian)(mian)大(da)部分被(bei)海洋覆蓋,真(zhen)正能(neng)(neng)夠(gou)到(dao)達陸(lu)地(di)表(biao)(biao)(biao)(biao)面(mian)(mian)(mian)(mian)的(de)太(tai)陽(yang)(yang)能(neng)(neng)只有(you)到(dao)達地(di)球(qiu)(qiu)范(fan)圍太(tai)陽(yang)(yang)輻(fu)射能(neng)(neng)量的(de)10%左右,致使在(zai)陸(lu)地(di)單位面(mian)(mian)(mian)(mian)積(ji)上(shang)能(neng)(neng)夠(gou)直接獲得的(de)太(tai)陽(yang)(yang)能(neng)(neng)量較少。通常以(yi)太(tai)陽(yang)(yang)輻(fu)照(zhao)度(du)(du)來表(biao)(biao)(biao)(biao)示,地(di)球(qiu)(qiu)表(biao)(biao)(biao)(biao)面(mian)(mian)(mian)(mian)輻(fu)照(zhao)度(du)(du)最高值約為1.2kw/㎡,且絕大(da)多(duo)數(shu)地(di)區和大(da)多(duo)數(shu)日照(zhao)時間內都低(di)于1kw/㎡。太(tai)陽(yang)(yang)能(neng)(neng)的(de)利用實際上(shang)是低(di)密度(du)(du)能(neng)(neng)量的(de)收集、利用。
2、占地面積大
由于(yu)太陽能能量密度低,這就(jiu)使得光(guang)(guang)伏(fu)發(fa)電系(xi)統的占地面(mian)(mian)積(ji)會很大,每10kw光(guang)(guang)伏(fu)發(fa)電功率占地約需100㎡,平(ping)均每平(ping)方(fang)米面(mian)(mian)積(ji)發(fa)電功率為100w。隨(sui)著光(guang)(guang)伏(fu)建筑一體化發(fa)電技術(shu)的成熟和發(fa)展,越(yue)來越(yue)多的光(guang)(guang)伏(fu)發(fa)電系(xi)統可以利用建筑物(wu)、構筑物(wu)的屋(wu)頂和立面(mian)(mian),將(jiang)逐漸克服光(guang)(guang)伏(fu)發(fa)電占地面(mian)(mian)積(ji)大的不(bu)足(zu)。
3、轉換效率低
光(guang)(guang)伏(fu)發電(dian)(dian)的(de)(de)最基本單元是(shi)太陽能電(dian)(dian)池(chi)組件。光(guang)(guang)伏(fu)發電(dian)(dian)的(de)(de)轉(zhuan)換(huan)(huan)效(xiao)率(lv)(lv)指(zhi)光(guang)(guang)能轉(zhuan)換(huan)(huan)為電(dian)(dian)能的(de)(de)比率(lv)(lv)。目(mu)前晶體硅(gui)(gui)光(guang)(guang)伏(fu)電(dian)(dian)池(chi)轉(zhuan)換(huan)(huan)效(xiao)率(lv)(lv)為13%~17%,非晶硅(gui)(gui)光(guang)(guang)伏(fu)電(dian)(dian)池(chi)只有5%~8%。由于光(guang)(guang)電(dian)(dian)轉(zhuan)換(huan)(huan)效(xiao)率(lv)(lv)太低,從(cong)而使光(guang)(guang)伏(fu)發電(dian)(dian)功率(lv)(lv)密度低,難以形成高功率(lv)(lv)發電(dian)(dian)系統(tong)。因此(ci),太陽能電(dian)(dian)池(chi)的(de)(de)轉(zhuan)換(huan)(huan)效(xiao)率(lv)(lv)低是(shi)阻礙光(guang)(guang)伏(fu)發電(dian)(dian)大(da)面積推(tui)廣(guang)的(de)(de)瓶頸。
4、間歇性工作
在(zai)地球表面,光伏發(fa)(fa)電(dian)系統只能(neng)在(zai)白天發(fa)(fa)電(dian),晚上不(bu)能(neng)發(fa)(fa)電(dian),除非(fei)在(zai)太(tai)空中沒有晝夜之分的情況下(xia),太(tai)陽能(neng)電(dian)池(chi)才可以連續發(fa)(fa)電(dian),這與人們(men)的用電(dian)需求不(bu)符。
5、受氣候環境因素影響大
太(tai)陽能(neng)光(guang)伏發電的(de)(de)(de)能(neng)源直接來源于(yu)太(tai)陽光(guang)的(de)(de)(de)照射(she),而地球表(biao)(biao)面上的(de)(de)(de)太(tai)陽照射(she)受(shou)氣候的(de)(de)(de)影響很大,長期的(de)(de)(de)雨雪天、陰(yin)天、霧天甚(shen)至云(yun)層(ceng)的(de)(de)(de)變(bian)化都會嚴重影響系統的(de)(de)(de)發電狀態(tai)。另外,環境因素的(de)(de)(de)影響也很大,比(bi)較突(tu)出的(de)(de)(de)一(yi)點是,空(kong)氣中的(de)(de)(de)顆粒物(如灰塵)等(deng)沉(chen)落在太(tai)陽能(neng)電池(chi)(chi)組件的(de)(de)(de)表(biao)(biao)面,阻(zu)擋了部分光(guang)線的(de)(de)(de)照射(she),這(zhe)樣會使(shi)電池(chi)(chi)組件轉換(huan)效率降低,從而造成(cheng)發電量減少甚(shen)至電池(chi)(chi)板的(de)(de)(de)損(sun)壞(huai)。
6、地域依賴性強
地(di)理位置不同,氣候不同,使(shi)各地(di)區(qu)日照資源相差很大。光伏發(fa)電系統只有應用在太陽能資源豐富的地(di)區(qu),其(qi)效果才會好。
7、系統成本高
由(you)于(yu)太陽(yang)能(neng)光伏發(fa)(fa)電(dian)(dian)的(de)(de)效(xiao)率較低,到(dao)目(mu)前為止(zhi),光伏發(fa)(fa)電(dian)(dian)的(de)(de)成本(ben)仍然是其他常(chang)規發(fa)(fa)電(dian)(dian)方式(shi)(如火力和(he)水力發(fa)(fa)電(dian)(dian))的(de)(de)幾倍,這是制約其廣(guang)泛(fan)應用的(de)(de)最(zui)主(zhu)要因(yin)素。但是也應看到(dao),隨(sui)著太陽(yang)能(neng)電(dian)(dian)池(chi)產(chan)能(neng)的(de)(de)不(bu)斷(duan)擴大(da)及電(dian)(dian)池(chi)片光電(dian)(dian)轉換效(xiao)率的(de)(de)不(bu)斷(duan)提高(gao),光伏發(fa)(fa)電(dian)(dian)系統的(de)(de)成本(ben)也下降(jiang)得(de)非常(chang)快。太陽(yang)能(neng)電(dian)(dian)池(chi)組(zu)件的(de)(de)價(jia)格(ge)幾十年來已經從最(zui)初的(de)(de)每(mei)瓦70多(duo)美元(yuan)下降(jiang)至目(mu)前的(de)(de)每(mei)瓦2美元(yuan)左(zuo)右(you)。
8、晶體硅電池的制造過程高污染、高能耗
晶(jing)體硅(gui)(gui)電池的主要(yao)原料(liao)是(shi)(shi)純凈的硅(gui)(gui)。硅(gui)(gui)是(shi)(shi)地球上含量(liang)僅次于氧的元素,主要(yao)存在形式是(shi)(shi)沙(sha)子(sio2)。從硅(gui)(gui)砂一步步變成純度為99.9999%以(yi)上的晶(jing)體硅(gui)(gui),要(yao)經過多道化(hua)學和物(wu)理(li)工(gong)序的處(chu)理(li),不僅要(yao)消耗大量(liang)能(neng)源,還會(hui)造(zao)成一定的環境污染。