一、光伏發電是什么意思
光(guang)伏(fu)發(fa)電(dian)是利(li)用(yong)半(ban)導體界面(mian)的(de)光(guang)生伏(fu)特(te)效應而將光(guang)能(neng)直接轉變為(wei)電(dian)能(neng)的(de)一種(zhong)技術。主(zhu)要(yao)由太陽電(dian)池(chi)板(組件(jian))、控(kong)制器和逆變器三大部分組成(cheng),主(zhu)要(yao)部件(jian)由電(dian)子元器件(jian)構成(cheng)。太陽能(neng)電(dian)池(chi)經過串聯(lian)后進(jin)行封裝(zhuang)保護可形成(cheng)大面(mian)積的(de)太陽電(dian)池(chi)組件(jian),再配合上功(gong)率控(kong)制器等部件(jian)就形成(cheng)了光(guang)伏(fu)發(fa)電(dian)裝(zhuang)置。
二、太陽能光伏發電對人體有輻射嗎
光伏系統(tong)有電(dian)磁輻(fu)射,但(dan)比較少,采用(yong)合格的(de)設備,不會(hui)對人體造成傷害和對家用(yong)電(dian)器(qi)造成干擾。光伏組(zu)件是直流電(dian),不會(hui)產生(sheng)輻(fu)射,逆變(bian)器(qi)的(de)輻(fu)射嚴格控(kong)制在(zai)安全(quan)范圍(wei)內。
光伏發電(dian)(dian)(dian)(dian)(dian)(dian)是(shi)(shi)將(jiang)光能(neng)通過半導體的(de)特性直(zhi)(zhi)(zhi)接轉化為(wei)直(zhi)(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)能(neng)的(de),再通過逆變(bian)(bian)器(qi)(qi)將(jiang)直(zhi)(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)轉換(huan)成可以被我們使用的(de)交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)。光伏系統(tong)是(shi)(shi)由光伏組(zu)件,支(zhi)架,直(zhi)(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)纜,逆變(bian)(bian)器(qi)(qi),交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)纜,配電(dian)(dian)(dian)(dian)(dian)(dian)柜,變(bian)(bian)壓器(qi)(qi)等組(zu)成,其中支(zhi)架不(bu)帶(dai)電(dian)(dian)(dian)(dian)(dian)(dian),自(zi)然不(bu)會產生(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)磁干擾。光伏組(zu)件和直(zhi)(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)纜,里面是(shi)(shi)直(zhi)(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu),方(fang)向(xiang)沒(mei)有(you)變(bian)(bian)化,只(zhi)能(neng)產生(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)場,不(bu)能(neng)產生(sheng)(sheng)磁場。輸出變(bian)(bian)壓器(qi)(qi)雖(sui)然是(shi)(shi)交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian),但頻率很(hen)低(di),只(zhi)有(you)50Hz,產生(sheng)(sheng)的(de)磁場很(hen)低(di)。逆變(bian)(bian)器(qi)(qi)是(shi)(shi)把(ba)直(zhi)(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)轉為(wei)交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)設備,里面有(you)電(dian)(dian)(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)(dian)(dian)子變(bian)(bian)換(huan),頻率一(yi)般為(wei)5-20KHz,因此會產生(sheng)(sheng)交變(bian)(bian)電(dian)(dian)(dian)(dian)(dian)(dian)場,所(suo)以也會產生(sheng)(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)磁輻射。但國家對光伏逆變(bian)(bian)器(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)磁兼容性有(you)嚴格(ge)的(de)標準(zhun)。光伏逆變(bian)(bian)器(qi)(qi)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)磁輻射,同家用電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)相比,大約和筆記本電(dian)(dian)(dian)(dian)(dian)(dian)腦差不(bu)多,低(di)于電(dian)(dian)(dian)(dian)(dian)(dian)磁爐,電(dian)(dian)(dian)(dian)(dian)(dian)吹風,冰箱。
因此,太陽能(neng)光伏發電不僅不會(hui)對人(ren)的健康(kang)產生危(wei)害,還可以為地球提供(gong)綠色(se)清潔的優(you)質能(neng)源,是(shi)人(ren)類未來能(neng)源發展方向。
三、太陽能光伏發電的優點
1、太陽(yang)能(neng)資源取之(zhi)不(bu)盡(jin),用(yong)之(zhi)不(bu)竭,照(zhao)射到地(di)球(qiu)(qiu)上的(de)太陽(yang)能(neng)要比人類目前消耗(hao)的(de)能(neng)量大6000倍。而且太陽(yang)能(neng)在地(di)球(qiu)(qiu)上分布廣(guang)泛,只要有光照(zhao)的(de)地(di)方就可以使用(yong)光伏發(fa)電(dian)系統,不(bu)受地(di)域、海拔(ba)等因素的(de)限(xian)制。
2、太陽能(neng)資源隨處可(ke)(ke)得,可(ke)(ke)就近供電(dian),不必長(chang)距(ju)離(li)(li)輸送(song),避免了(le)長(chang)距(ju)離(li)(li)輸電(dian)線路所造成的(de)電(dian)能(neng)損失。
3、光伏發電的(de)能(neng)量轉換(huan)過程簡單,是直接從光能(neng)到電能(neng)的(de)轉換(huan),沒有中間過程(如熱能(neng)轉換(huan)為機械(xie)能(neng)、機械(xie)能(neng)轉換(huan)為電磁能(neng)等)和機械(xie)運動,不存在機械(xie)磨損。根據熱力(li)學分析,光伏發電具有很高的(de)理(li)論發電效率,可達80%以上,技術開發潛(qian)力(li)巨大。
4、光伏發電本身(shen)不(bu)(bu)使(shi)用燃料(liao)(liao),不(bu)(bu)排(pai)放包(bao)括溫室氣體(ti)和(he)其它廢(fei)氣在內(nei)的任何物質,不(bu)(bu)污染空氣,不(bu)(bu)產生噪(zao)聲(sheng),對環(huan)(huan)境友(you)好,不(bu)(bu)會遭受能源(yuan)(yuan)危機或(huo)燃料(liao)(liao)市場不(bu)(bu)穩(wen)定而造(zao)成的沖擊,是真(zhen)正(zheng)綠色環(huan)(huan)保(bao)的新型可再生能源(yuan)(yuan)。
5、光伏(fu)發電(dian)過程不需要冷(leng)卻水(shui),可(ke)以(yi)安裝(zhuang)在沒有水(shui)的荒漠戈壁上。光伏(fu)發電(dian)還可(ke)以(yi)很方便地與(yu)建(jian)筑物結合,構成光伏(fu)建(jian)筑一體化發電(dian)系統(tong),不需要單獨占地,可(ke)節省寶貴的土地資(zi)源。
6、光伏發電(dian)無(wu)機(ji)械傳動(dong)部件(jian),操(cao)作、維護簡單,運(yun)行(xing)穩定可靠。一套光伏發電(dian)系統(tong)只要有(you)太陽能(neng)電(dian)池組件(jian)就能(neng)發電(dian),加(jia)之(zhi)自動(dong)控制技術的廣泛采用,基本上(shang)可實現無(wu)人值守,維護成本低。
7、光伏(fu)發(fa)電系統工作性能穩定可靠,使用壽命(ming)長(chang)(30年以(yi)上)。晶體(ti)硅太陽能電池壽命(ming)可長(chang)達20~35年。在光伏(fu)發(fa)電系統中,只要(yao)設計合理(li)、選型適當,蓄電池的(de)壽命(ming)也可長(chang)達10~15年。
8、太(tai)陽(yang)能電池(chi)組件結構簡單,體積小、重(zhong)量輕,便于運輸和安裝。光伏(fu)發電系(xi)統建設周期短,而(er)且根據用(yong)電負荷容(rong)(rong)量可大(da)可小,方便靈活,極易組合、擴(kuo)容(rong)(rong)。
四、太陽能光伏發電的缺點
1、能量密度低
盡(jin)管太(tai)(tai)陽投(tou)向地球(qiu)的(de)(de)能(neng)(neng)量(liang)總和極(ji)其巨大(da),但由于地球(qiu)表(biao)面(mian)積也很大(da),而且地球(qiu)表(biao)面(mian)大(da)部分被(bei)海洋覆蓋,真正(zheng)能(neng)(neng)夠到(dao)達(da)陸(lu)地表(biao)面(mian)的(de)(de)太(tai)(tai)陽能(neng)(neng)只有到(dao)達(da)地球(qiu)范圍太(tai)(tai)陽輻(fu)(fu)射能(neng)(neng)量(liang)的(de)(de)10%左右,致使在陸(lu)地單(dan)位面(mian)積上能(neng)(neng)夠直接獲得(de)的(de)(de)太(tai)(tai)陽能(neng)(neng)量(liang)較(jiao)少(shao)。通常以太(tai)(tai)陽輻(fu)(fu)照度來表(biao)示(shi),地球(qiu)表(biao)面(mian)輻(fu)(fu)照度最高值(zhi)約為(wei)1.2kw/㎡,且絕大(da)多數地區和大(da)多數日照時間內都低于1kw/㎡。太(tai)(tai)陽能(neng)(neng)的(de)(de)利(li)用實際(ji)上是低密度能(neng)(neng)量(liang)的(de)(de)收集、利(li)用。
2、占地面積大
由于太陽(yang)能能量密度(du)低,這就使得光(guang)伏發電(dian)(dian)系統的(de)占(zhan)地(di)面積(ji)會(hui)很大,每10kw光(guang)伏發電(dian)(dian)功率占(zhan)地(di)約(yue)需100㎡,平(ping)均每平(ping)方(fang)米面積(ji)發電(dian)(dian)功率為100w。隨著光(guang)伏建筑(zhu)一體化發電(dian)(dian)技(ji)術的(de)成熟和(he)發展,越來越多(duo)的(de)光(guang)伏發電(dian)(dian)系統可以利用(yong)建筑(zhu)物、構筑(zhu)物的(de)屋頂和(he)立面,將逐漸克(ke)服光(guang)伏發電(dian)(dian)占(zhan)地(di)面積(ji)大的(de)不足。
3、轉換效率低
光(guang)(guang)伏(fu)發(fa)(fa)(fa)電(dian)的(de)最基本(ben)單元是(shi)太(tai)陽能(neng)電(dian)池(chi)組件。光(guang)(guang)伏(fu)發(fa)(fa)(fa)電(dian)的(de)轉(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)(lv)指光(guang)(guang)能(neng)轉(zhuan)換(huan)(huan)為電(dian)能(neng)的(de)比率(lv)(lv)(lv)。目前(qian)晶(jing)體(ti)硅光(guang)(guang)伏(fu)電(dian)池(chi)轉(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)(lv)為13%~17%,非晶(jing)硅光(guang)(guang)伏(fu)電(dian)池(chi)只有(you)5%~8%。由于光(guang)(guang)電(dian)轉(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)(lv)太(tai)低(di),從而使光(guang)(guang)伏(fu)發(fa)(fa)(fa)電(dian)功率(lv)(lv)(lv)密度(du)低(di),難以形成高功率(lv)(lv)(lv)發(fa)(fa)(fa)電(dian)系統。因此,太(tai)陽能(neng)電(dian)池(chi)的(de)轉(zhuan)換(huan)(huan)效(xiao)(xiao)率(lv)(lv)(lv)低(di)是(shi)阻(zu)礙光(guang)(guang)伏(fu)發(fa)(fa)(fa)電(dian)大面積(ji)推廣的(de)瓶(ping)頸。
4、間歇性工作
在地球(qiu)表面(mian),光伏(fu)發電(dian)系統(tong)只能(neng)在白天發電(dian),晚上不能(neng)發電(dian),除非在太空中(zhong)沒有晝夜之(zhi)分的情況(kuang)下,太陽能(neng)電(dian)池(chi)才可(ke)以連(lian)續發電(dian),這與人們的用(yong)電(dian)需求不符。
5、受氣候環境因素影響大
太陽(yang)(yang)能光(guang)伏發(fa)電(dian)(dian)的(de)能源直(zhi)接來源于(yu)太陽(yang)(yang)光(guang)的(de)照射,而地(di)球表(biao)面上的(de)太陽(yang)(yang)照射受氣候的(de)影響(xiang)很大,長期的(de)雨雪天、陰天、霧天甚至(zhi)(zhi)云層的(de)變化(hua)都會嚴重(zhong)影響(xiang)系統的(de)發(fa)電(dian)(dian)狀態(tai)。另(ling)外,環境因素的(de)影響(xiang)也很大,比較突(tu)出的(de)一點是,空(kong)氣中(zhong)的(de)顆粒物(如灰(hui)塵(chen))等沉落在(zai)太陽(yang)(yang)能電(dian)(dian)池組件的(de)表(biao)面,阻擋了(le)部分光(guang)線的(de)照射,這(zhe)樣會使(shi)電(dian)(dian)池組件轉換(huan)效率降低,從(cong)而造成發(fa)電(dian)(dian)量減少甚至(zhi)(zhi)電(dian)(dian)池板的(de)損壞。
6、地域依賴性強
地(di)(di)理(li)位置(zhi)不同,氣(qi)候不同,使各地(di)(di)區(qu)日照資(zi)源相差很大。光伏(fu)發電系(xi)統(tong)只有(you)應(ying)用在太陽(yang)能資(zi)源豐富的(de)地(di)(di)區(qu),其效果才(cai)會好。
7、系統成本高
由(you)于(yu)太(tai)陽能(neng)(neng)光伏(fu)(fu)發(fa)(fa)電(dian)(dian)(dian)的(de)(de)(de)(de)(de)效率較(jiao)低(di),到(dao)目前為(wei)止,光伏(fu)(fu)發(fa)(fa)電(dian)(dian)(dian)的(de)(de)(de)(de)(de)成本仍然是其他常(chang)規發(fa)(fa)電(dian)(dian)(dian)方(fang)式(如火力和(he)水(shui)力發(fa)(fa)電(dian)(dian)(dian))的(de)(de)(de)(de)(de)幾(ji)倍,這是制約其廣泛應用的(de)(de)(de)(de)(de)最(zui)(zui)主要(yao)因素。但是也應看到(dao),隨(sui)著太(tai)陽能(neng)(neng)電(dian)(dian)(dian)池(chi)產能(neng)(neng)的(de)(de)(de)(de)(de)不(bu)斷擴大及電(dian)(dian)(dian)池(chi)片光電(dian)(dian)(dian)轉換(huan)效率的(de)(de)(de)(de)(de)不(bu)斷提(ti)高,光伏(fu)(fu)發(fa)(fa)電(dian)(dian)(dian)系統的(de)(de)(de)(de)(de)成本也下降得非常(chang)快。太(tai)陽能(neng)(neng)電(dian)(dian)(dian)池(chi)組件的(de)(de)(de)(de)(de)價格幾(ji)十(shi)年來已經從最(zui)(zui)初的(de)(de)(de)(de)(de)每(mei)(mei)瓦70多美元(yuan)下降至(zhi)目前的(de)(de)(de)(de)(de)每(mei)(mei)瓦2美元(yuan)左右。
8、晶體硅電池的制造過程高污染、高能耗
晶體硅電池的(de)主要(yao)原料是純凈的(de)硅。硅是地球上(shang)含量僅次于氧的(de)元素,主要(yao)存在(zai)形式是沙子(sio2)。從硅砂一步步變(bian)成純度為99.9999%以上(shang)的(de)晶體硅,要(yao)經過多道化學和物理(li)工序(xu)的(de)處理(li),不僅要(yao)消耗大量能源,還會(hui)造(zao)成一定的(de)環(huan)境污(wu)染。