太阳能跟踪系统：太阳能电池有效利用外文翻译

1、大学毕业设计外文翻译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 t

2、he panel at 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

3、 discovery 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

4、. solar arrays 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 realisa

5、tion of fossil fuel's 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,

6、 with solar power 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 generat

7、ion, and will drop 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

8、gathering losses. light gathering is dependent on the angle of incidence of the light source providing power (i.e. the sun) to the solar cell's 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

9、 the day the sunlight 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 p

10、ower until at the point 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 ma

11、intain the maximum power 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 r

12、eal-time tracking would 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 depende

13、nt resistor to detect 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

14、arrives, the tracker 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 phototransis

15、tor. the motor turns 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.

16、 they have been set 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

17、 in determining the 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 sunlig

18、ht, as the angle of 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

19、will cause more light 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 a

20、t each cell, which can 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 pol

21、ycrystalline silicon 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 dissipa

22、te 9w that would match the panel's rating 9w at 12v corresponds to a current of 0.75a, so by ohm's 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 c

23、onnected in a charging arrangement 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 simi

24、lar conditions including no cloud 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

25、was found that in this case, the 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 pa

26、nel reached up to 400%.this amounts 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 am

27、meter was placed in series with 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

28、 collection efficiency increase 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 s

29、olar tracking device. by extracting 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

30、 a means of increasing overall 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 p

31、anel, owing to its simple construction 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. t

32、he geared support was removed 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 si

33、ngle axis tracker such as the 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

34、 use by domestic or commercial 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 variabl

35、e indication of their relative 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.refe

36、rences fahrenburch, a and bube, 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 s

37、ino-german technical cooperation project", 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 ma

38、nagement system for photovoltaic systems, international 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 re

39、forms, cambridge university press, 1994. damm, j. issue #17, june/july 1990. an active solar tracking system, homebrew magazine.太阳能跟踪系统：太阳能电池有效利用摘要-文章介绍了使用步进电机和光传感器跟踪太阳的简单方法潜在的好处，用此方法可以提高功率、效率，高级装置可以跟踪太阳以保持部分光线垂直照射，并有太阳能跟踪系统的设计，实施和实验测试、细节的设计和实验结果。关键词-可再生能源，优化功率1.前言近几年来，太阳能电池板的半导体光电材料能转换成直接使用的直流电压，使太

40、阳能通过光电原理发电成为现实。使用太阳能电池板阵列，就是将一系列的太阳能电池板连接，直流电压产生可实际使用的负荷。越来越多的太阳能电池板或面板正在使用，且效率达到很高的水平，而在偏远地区经常使用的供电线路是不经济的。这种取之不尽，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。其实早在75或100年前可再生能源用于发电的形式，已经在一定程度上被使用，如太阳能，风能，水能和地热不同程度上都被成功地得到充分利用，使用最广泛的是水力和风力发电。太阳能发电在全世界使用不太普及，这主要因为太阳能电池板成本较高和转换效率低。太阳能发电正在大力研究，太阳能发电成本现在已经能达到几美分内以每千瓦/小

41、时的发电量。由于新技术的使用，太阳能发电成本会进一步下降，如钛氧化物电池，实验室发电效率为32 ，平均效率的15-20 ，太阳能发电系统已经能代替可再生能源。能量损失包括减少逆变损失，储存损失，光聚集的损失。聚光依赖于光源的入射角，入射角在太阳能电池板表面接近垂直，其功率最大。如果一个单位的太阳能电池板将被安装在水平地面，很显然，在这一天，所有的太阳光入射角接近早上和晚上。在这样一个角度来看，聚集太阳光能基本上是零，因此没有产生电能。随着时间的流逝，以中午太阳光的入射角为零度 ，稳步增加，直到太阳光入射角垂直于太阳能电池板，其功率达到最大。相反，当到黄昏时，越来越多因角度引起的功率，其功率再次

42、降到最低。在这种情况下，我们认为有必要保持输出功率最大，保持入射角接近垂直最好。由太阳能电池板倾斜，不断面对太阳，这是可以实现的。这一过程的遥感控制和以下的叙述，被称为太阳能跟踪。为了解决对太阳的现实时跟踪，有必要采取有效的太阳光照，这样任何数据（太阳光照）都能运行。2 .敏感元件和信号处理最简单的方法就是使用一个ldr灯，通过察觉灯表面发亮强度来改变跟踪器的位置。另外一种方法，如杰夫达姆发明主页电源，就是利用太阳光照射在两个光电晶体管上，并提出了许多跟踪太阳方法。如图1所示：a状态 b状态 c状态图.1供选择的太阳跟踪的方法当清晨来临，跟踪器便图a所示：左边的光电晶体管被启动，发出信号使得电

43、动机持续转动直到金属板形成阴暗面，使得跟踪器返回并且呈现图b所示；而随着时间慢慢过去，不一会便转到c图，继而启动右边的光电晶体管。电动机又会转动直到再次出现图b所显示的状态，周而复始直至夜幕降临，或是直到达到最小探测光的程度。设计好像有一个狭窄的感光度范围，感光度是在光电晶体管电路偏置条件下成立的。正是由于这个原因成立，太阳能电池板本身被选为是遥感装置，提供一个很好的光照强度检测机制。因为遥感装置很敏感，不同的光线提供一个近似线性电压范围，在倾斜或歪曲的阳光，由这个范围来确定有用的光线。因此，这是一个两个太阳能电池板相反方向而立简单的三角形装置。如图2所示：图.2太阳参比室设定在其他位置太阳能

44、电池板能接收同等数量的阳光，虽然入射角不是90度 ，相当于一下这两种情况，如图3所示：图.3太阳参比室休息位置随着太阳的移动，如图4所示，假设太阳能跟踪器尚未改变入射角，即将造成很多的太阳光不能利用。图.4太阳参比室相对太阳的有效角度这将明显地导致电压区别，太阳电池板对比其他将有更高发展潜力。 在太阳板面上这种现象产生一个可发现的信号，可以由一条适当的电路处理。3.a原型太阳跟踪仪最后阶段参与耦合电路，把电机安装在支架上。最终完整的产品如图5 所示：图.5原型太阳跟踪仪它有一个由安装在轮缘上的多晶硅组成的solarex 9w太阳能电池板列阵，该装置的制作灵感来自于那些技术人员。简单地说有两个测试对象进行测试。第一种情况是消除跟踪器和平面安装位置的误差，输出连接到负载，将消除9瓦，符合控制板的功率规定为9瓦，而在12伏的对应电流0.75安 ，因此由欧姆定律来计算负载的电阻为16欧。50瓦的负载是最接近控制板的测试值，跟踪器设备仍然需要电力，太阳能电池板连接在一个充电的12v电池上给跟踪器设备供电，负载电压和电流通过两个单独的