太陽(yáng)能跟蹤系統(tǒng)：太陽(yáng)能電池有效利用外文翻譯

1、solar tracking system: more efficient use ofsolar panelsabstract-this paper shows the potential system benefits of simple tracking solar system using a stepper motor and light sensor. this method is increasing power collection efficiency by developing a device that tracks the sun to keep the panel a

2、t a right angle to its rays. a solar tracking system is designed, implemented and experimentally tested. the design details and the experimental results are shown. keywords-renewable energy, power optimization.introductionextracting useable electricity from the sun was made possible by the discovery

3、 of the photoelectric mechanism and subsequent development of the solar cell a semi-conductive material that converts visible light into a direct current. by using solar arrays, a series of solar cells electrically connected, a dc voltage is generated which can be physically used on a load. solar ar

4、rays or panels are being used increasingly as efficiencies reach higher levels, and are especially popular in remote areas where placement of electricity lines is not economically viable.this alternative power source is continuously achieving greater popularity especially since the realisation of fo

5、ssil fuels shortcomings. renewable energy in the form of electricity has been in use to some degree as long as 75 or 100 years ago. sources such as solar, wind, hydro and geo- thermal have all been utilised with varying levels of success. the most widely used are hydro and wind power, with solar pow

6、er being moderately used worldwide. this can be attributed to the relatively high cost of solar cells and their low conversion efficiency. solar power is being heavily researched, and solar energy costs have now reached within a few cents per kw/h of other forms of electricity generation, and will d

7、rop further with new technologies such as titanium-oxide cells. with a peak laboratory efficiency of 32% and average efficiency of 15-20%, it is necessary to recover as much energy as possible from a solar power system.this includes reducing inverter losses, storage losses, and light gathering losse

8、s. light gathering is dependent on the angle of incidence of the light source providing power (i.e. the sun) to the solar cells surface, and the closer to perpendicular, the greater the power. if a flat solar panel is mounted on level ground, it is obvious that over the course of the day the sunligh

9、t will have an angle of incidence close to in the morning and the evening. at such an angle, the light gathering ability of the cell is essentially zero, resulting in no output. as the day progresses to midday, the angle of incidence approaches 00, causing an steady increase in power until at the po

10、int where the light incident on the panel is completely perpendicular, and maximum power is achieved.as the day continues toward dusk, the reverse happens, and the increasing angle causes the power to decrease again toward minimum again.from this background, we see the need to maintain the maximum p

11、ower output from the panel by maintaining an angle of incidence as close to as possible. by tilting the solar panel to continuously face the sun, this can be achieved. this process of sensing and following the position of the sun is known as solar tracking. it was resolved that real-time tracking wo

12、uld be necessary to follow the sun effectively, so that no external data would be required in operation.2.the sensing element and signal processingmany different methods have been proposed and used to track the position of the sun. the simplest of all uses an ldr- a light dependent resistor to detec

13、t light intensity changes on the surface of the resistor. other methods, such as that published by jeff damm in home power, use two phototransistors covered with a small plate to act as a shield to sunlight, as shown in fig. 1. fig.1 alternative solar tracking methodwhen morning arrives, the tracker

14、 is in state a from the previous day. the left phototransistor is turned on, causing a signal to turn the motor continuously until the shadow from the plate returns the tracker to state b. as the day slowly progresses, state c is reached shortly, turning on the right phototransistor. the motor turns

15、 until state b is reached again, and the cycle continues until the end of the day, or until the minimum detectable light level is reached. the problem with a design like have a narrow range of sensitivity, this is that phototransistors once in a circuit under set bias conditions. they have been set

16、up it was because of this fact that solar cells themselves were chosen to be the sensing devices. they provide an excellent mechanism in light intensity detection- because they are sensitive to varying light and provide a near-linear voltage range that can be used to an advantage in determining the

17、present declination or angle to the sun. as a result, a simple triangular set-up was proposed, with the two solar cells facing opposite directions, as shown in fig. 2.fig.2 set-up of solar reference cellsin its rest position, the solar cells both receive an equal amount of sunlight, as the angle of

18、incidence, although not 900, is equal in both cases as seen in fig. 3.fig.3solar reference cells at rest position it can be seen in fig. 4 that as the sun moves in the sky, assuming that the solar tracker has not yet moved, the angle of incidence of light to the reference panels will cause more ligh

19、t to fall on one cell than the other. fig.4 solar reference cells at a significant angle to the sunthis will obviously cause a voltage difference, where the cell that is facing the sun will have higher potential than the other. this phenomenon will result in a detectable signal at each cell, which c

20、an be processed by a suitable circuit. 3.a prototype solar trackerthe final stage involved coupling the circuitry to the motor and mounting it onto the bracket. the final product is seen complete in fig. 5.fig.5 a prototype solar trackerit has a solarex 9w solar array made of polycrystalline silicon

21、 mounted on the flanges, which was borrowed from the tech officers.quite simply having two test subjects carried out testing. the first scenario involved removing the panel from the tracker and laying it in a flat orientation. the output was connected to a load that would dissipate 9w that would mat

22、ch the panels rating 9w at 12v corresponds to a current of 0.75a, so by ohms law; a load resistance was calculated as being . a 50w resistor was the closest value found and was connected to the panel. the tracking device still requires power, but a 12v battery that is connected in a charging arrange

23、ment with the solar panel supplies it. the voltage across and current through the load was monitored using two separate multimeters, and was recorded every half- hour on a clear day into an excel spreadsheet. the readings were taken on a span of days that possessed similar conditions including no cl

24、oud cover. the readings are shown below in a graph generated by excel in fig. 6. fig.6 experimental resulte of power increase for tracked panelit is possible to calculate a percentage increase and an average increase by writing the appropriate calculations in excel. it was found that in this case, t

25、he fixed panel provided an average of 39% of its 9w, or 3.51w, calculated over a 12- hour period. by contrast, the tracked solar panel achieved an overall 71 % output, or 6.3w over the same time frame. at the earlier and later hours, the power increase over the fixed panel reached up to 400%.this am

26、ounts to an average 30% increase in power simply by maintaining the solar panel as perpendicular as possible to the sun. to ensure that power was not being wasted, the device itself was also monitored for current drawn to power itself. when the device was at rest, an ammeter was placed in series wit

27、h the battery. the total current at 12v was measured as only 4ma, which corresponded to a power dissipation of 48mw under no load. 4. discussion a solar tracker was proposed, designed and constructed. the final design was successful, in that it achieved an overall power collection efficiency increas

28、e from only 39% for a fixed panel to over 70% for the same panel on the tracking device. in terms of real value, this means that the overall cost of a system can be reduced significantly, considering that much more power can be supplied by the solar array coupled to a solar tracking device. by extra

29、cting more power from the same solar panel, the cost per watt is decreased, thereby rendering solar power much more cost-effective than previously achieved using fixed solar panels.the high outlay in a solar tracking system has been a factor that discouraged tracking as a means of increasing overall

30、 solar efficiency. many commercial units cost in excess of us $2000 for a unit that can track the sun while bearing a panel of considerable weight. the device presented in this thesis is capable of supporting a load of at least 8 kg, the average weight of a 75 w solar panel, owing to its simple cons

31、truction and the high torque capabilities of the motor. the parts used for this device were also extremely low-cost, with the total value using parts found from scrap sources being a total of about a $ 30, including all electronic components and solar reference cells. the geared support was removed

32、from an old security camera, the stepping motor from an old printer, and all other parts, excluding the 9w solar panel, were sourced from various scrap items. however, if all these parts would have to be purchased, the cost would be projected at no more than a$ 100.a single axis tracker such as the

33、one made offers a great power increase over a fixed solar panel, but a two-axis tracker would provide more power still. this could be a subject for further development.solar tracking is by far the easiest method to increase overall efficiency of a solar power system for use by domestic or commercial

34、 users. by utilising this simple design, it is possible for an individual to construct the device themselves. 5. conclusiona solar tracker is designed employing the new principle of using small solar cells to function as self-adjusting light sensors, providing a variable indication of their relative

35、 angle to the sun by detecting their voltage output. by using this method, the solar tracker was successful in maintaining a solar array at a sufficiently perpendicular angle to the sun. the power increase gained over a fixed horizontal array was in excess of 30%.6.references fahrenburch, a and bube

36、, r. 1983, fundamentals of solar cells, academicpress, new york. partain, l.d.1995,sollar cells and their applications, john wiley& ,sons. new york. e weise, r klockner, r kniel, ma sheng hong, qin jian ping, remote power supply using wind and solar energy-a sino-german technical cooperation project

37、, beijing international conference on wind energy, beijing, 1995. wichert b, lawrance w, friese t, first experiences with a novel predictive control strategy for pv-diesel hybrid energy systems, 1999. duryea s, syed i, lawrence w, an automated battery management system for photovoltaic systems, inte

38、rnational journal of renewable energy engineering, vol i, no 2, aug 1999. twidell j, weir j, renewable energy systems, chapmanand hall, 1994 centre for resources and environmental studies,anu, sustainable, energy systems pathways for australian energy reforms, cambridge university press, 1994. damm,

39、 j. issue #17, june/july 1990. an active solar tracking system, homebrew magazine.太陽(yáng)能跟蹤系統(tǒng)：太陽(yáng)能電池有效利用摘要-文章介紹了使用步進(jìn)電機(jī)和光傳感器跟蹤太陽(yáng)的簡(jiǎn)單方法潛在的好處，用此方法可以提高功率、效率，高級(jí)裝置可以跟蹤太陽(yáng)以保持部分光線垂直照射，并有太陽(yáng)能跟蹤系統(tǒng)的設(shè)計(jì)，實(shí)施和實(shí)驗(yàn)測(cè)試、細(xì)節(jié)的設(shè)計(jì)和實(shí)驗(yàn)結(jié)果。關(guān)鍵詞-可再生能源，優(yōu)化功率1.前言近幾年來(lái)，太陽(yáng)能電池板的半導(dǎo)體光電材料能轉(zhuǎn)換成直接使用的直流電壓，使太陽(yáng)能通過(guò)光電原理發(fā)電成為現(xiàn)實(shí)。使用太陽(yáng)能電池板陣列，就是將一系列的太陽(yáng)能電池板連接，直流電壓

40、產(chǎn)生可實(shí)際使用的負(fù)荷。越來(lái)越多的太陽(yáng)能電池板或面板正在使用，且效率達(dá)到很高的水平，而在偏遠(yuǎn)地區(qū)經(jīng)常使用的供電線路是不經(jīng)濟(jì)的。這種取之不盡，用之不完可代替的新能源得到普及，主要原因是化石燃料的不足。其實(shí)早在75或100年前可再生能源用于發(fā)電的形式，已經(jīng)在一定程度上被使用，如太陽(yáng)能，風(fēng)能，水能和地?zé)岵煌潭壬隙急怀晒Φ氐玫匠浞掷茫褂米顝V泛的是水力和風(fēng)力發(fā)電。太陽(yáng)能發(fā)電在全世界使用不太普及，這主要因?yàn)樘?yáng)能電池板成本較高和轉(zhuǎn)換效率低。太陽(yáng)能發(fā)電正在大力研究，太陽(yáng)能發(fā)電成本現(xiàn)在已經(jīng)能達(dá)到幾美分內(nèi)以每千瓦/小時(shí)的發(fā)電量。由于新技術(shù)的使用，太陽(yáng)能發(fā)電成本會(huì)進(jìn)一步下降，如鈦氧化物電池，實(shí)驗(yàn)室發(fā)電效率為3

41、2 ，平均效率的15-20 ，太陽(yáng)能發(fā)電系統(tǒng)已經(jīng)能代替可再生能源。能量損失包括減少逆變損失，儲(chǔ)存損失，光聚集的損失。聚光依賴于光源的入射角，入射角在太陽(yáng)能電池板表面接近垂直，其功率最大。如果一個(gè)單位的太陽(yáng)能電池板將被安裝在水平地面，很顯然，在這一天，所有的太陽(yáng)光入射角接近早上和晚上。在這樣一個(gè)角度來(lái)看，聚集太陽(yáng)光能基本上是零，因此沒(méi)有產(chǎn)生電能。隨著時(shí)間的流逝，以中午太陽(yáng)光的入射角為零度 ，穩(wěn)步增加，直到太陽(yáng)光入射角垂直于太陽(yáng)能電池板，其功率達(dá)到最大。相反，當(dāng)?shù)近S昏時(shí)，越來(lái)越多因角度引起的功率，其功率再次降到最低。在這種情況下，我們認(rèn)為有必要保持輸出功率最大，保持入射角接近垂直最好。由太陽(yáng)能電池

42、板傾斜，不斷面對(duì)太陽(yáng)，這是可以實(shí)現(xiàn)的。這一過(guò)程的遙感控制和以下的敘述，被稱為太陽(yáng)能跟蹤。為了解決對(duì)太陽(yáng)的現(xiàn)實(shí)時(shí)跟蹤，有必要采取有效的太陽(yáng)光照，這樣任何數(shù)據(jù)（太陽(yáng)光照）都能運(yùn)行。2 .敏感元件和信號(hào)處理最簡(jiǎn)單的方法就是使用一個(gè)ldr燈，通過(guò)察覺(jué)燈表面發(fā)亮強(qiáng)度來(lái)改變跟蹤器的位置。另外一種方法，如杰夫達(dá)姆發(fā)明主頁(yè)電源，就是利用太陽(yáng)光照射在兩個(gè)光電晶體管上，并提出了許多跟蹤太陽(yáng)方法。如圖1所示：a狀態(tài) b狀態(tài) c狀態(tài)圖.1供選擇的太陽(yáng)跟蹤的方法當(dāng)清晨來(lái)臨，跟蹤器便圖a所示：左邊的光電晶體管被啟動(dòng)，發(fā)出信號(hào)使得電動(dòng)機(jī)持續(xù)轉(zhuǎn)動(dòng)直到金屬板形成陰暗面，使得跟蹤器返回并且呈現(xiàn)圖b所示；而隨著時(shí)間慢慢過(guò)去，不一會(huì)

43、便轉(zhuǎn)到c圖，繼而啟動(dòng)右邊的光電晶體管。電動(dòng)機(jī)又會(huì)轉(zhuǎn)動(dòng)直到再次出現(xiàn)圖b所顯示的狀態(tài)，周而復(fù)始直至夜幕降臨，或是直到達(dá)到最小探測(cè)光的程度。設(shè)計(jì)好像有一個(gè)狹窄的感光度范圍，感光度是在光電晶體管電路偏置條件下成立的。正是由于這個(gè)原因成立，太陽(yáng)能電池板本身被選為是遙感裝置，提供一個(gè)很好的光照強(qiáng)度檢測(cè)機(jī)制。因?yàn)檫b感裝置很敏感，不同的光線提供一個(gè)近似線性電壓范圍，在傾斜或歪曲的陽(yáng)光，由這個(gè)范圍來(lái)確定有用的光線。因此，這是一個(gè)兩個(gè)太陽(yáng)能電池板相反方向而立簡(jiǎn)單的三角形裝置。如圖2所示：圖.2太陽(yáng)參比室設(shè)定在其他位置太陽(yáng)能電池板能接收同等數(shù)量的陽(yáng)光，雖然入射角不是90度 ，相當(dāng)于一下這兩種情況，如圖3所示：圖.3

44、太陽(yáng)參比室休息位置隨著太陽(yáng)的移動(dòng)，如圖4所示，假設(shè)太陽(yáng)能跟蹤器尚未改變?nèi)肷浣牵磳⒃斐珊芏嗟奶?yáng)光不能利用。圖.4太陽(yáng)參比室相對(duì)太陽(yáng)的有效角度這將明顯地導(dǎo)致電壓區(qū)別，太陽(yáng)電池板對(duì)比其他將有更高發(fā)展?jié)摿Α?在太陽(yáng)板面上這種現(xiàn)象產(chǎn)生一個(gè)可發(fā)現(xiàn)的信號(hào)，可以由一條適當(dāng)?shù)碾娐诽幚怼?.a原型太陽(yáng)跟蹤儀最后階段參與耦合電路，把電機(jī)安裝在支架上。最終完整的產(chǎn)品如圖5 所示：圖.5原型太陽(yáng)跟蹤儀它有一個(gè)由安裝在輪緣上的多晶硅組成的solarex9w太陽(yáng)能電池板列陣，該裝置的制作靈感來(lái)自于那些技術(shù)人員。簡(jiǎn)單地說(shuō)有兩個(gè)測(cè)試對(duì)象進(jìn)行測(cè)試。第一種情況是消除跟蹤器和平面安裝位置的誤差，輸出連接到負(fù)載，將消除9瓦，符合控制板的功率規(guī)定為9瓦，而在12伏的對(duì)應(yīng)電流0.75安 ，因此由歐姆定律來(lái)計(jì)算負(fù)載的電阻為16歐。50瓦的負(fù)載是最接近控制板的測(cè)試值，跟蹤器設(shè)備仍然需要電力，太陽(yáng)能電池板連接在一個(gè)充電的12v電池上給跟蹤器設(shè)備供電，負(fù)載電壓和電流通過(guò)兩個(gè)單獨(dú)的萬(wàn)用表