0 1 00:00:05,750 --> 00:00:11,090 Hi everyone welcome back to PV Solar energy course. 1 2 00:00:11,220 --> 00:00:20,110 Today we are going to discuss two main parameters first one is the conversion efficiency. 2 3 00:00:20,110 --> 00:00:32,740 This is the ratio between the power coming out of the solar cell or Pout and the light power of 3 4 00:00:33,130 --> 00:00:41,930 photons on the solar cell or in other war going into the solar cell Pin 4 5 00:00:44,960 --> 00:00:55,570 the conversion efficiencies of solar cell are defined in its maximum power point so that power output 5 6 00:00:55,720 --> 00:01:09,700 equal to P maximum as discussed which equals to Imp times Vmp this product equal to the product 6 7 00:01:09,760 --> 00:01:22,210 of short circuit current with open circuit voltage and the fill factor as a result of the energy conversion 7 8 00:01:22,270 --> 00:01:31,640 efficiency can be expressed in external parameter of solar cell, the open circuit voltage and 8 9 00:01:31,640 --> 00:01:41,720 short circuit current and fill factor as shown in this equation the efficiency equal to P output over 9 10 00:01:41,720 --> 00:01:55,640 P input. the power output the output power is equal to the maximum power which equal Vmp times Imp 10 11 00:01:55,640 --> 00:02:08,190 which are also equal to open circuit voltage times short circuit current times fill factor. To be able to compare 11 12 00:02:08,200 --> 00:02:11,730 the efficiencies of different solar cell. 12 13 00:02:11,740 --> 00:02:17,290 The so-called standard test condition have been introduced. 13 14 00:02:18,880 --> 00:02:27,730 The standard test condition describes the condition for the Pin and the temperature of solar cell during 14 15 00:02:27,850 --> 00:02:34,080 the IV measures the temperature of solar cells under Z standard. 15 16 00:02:34,090 --> 00:02:44,900 test condition is determined to be 25 degrees celuis. the solar spectrum has the special 16 17 00:02:44,900 --> 00:02:55,690 shape of AM 1.5 and a total irradiation of 1000 W/meter2 17 18 00:02:59,730 --> 00:03:12,220 A typical solar spectrum with the shape of AM 1.5 is shown in the right figure on the left vertical 18 19 00:03:12,490 --> 00:03:13,360 axis. 19 20 00:03:13,420 --> 00:03:23,410 We show the power density the irradiance under the standard. 20 21 00:03:23,450 --> 00:03:32,150 test condition has to be equal to 1000 watt/square meter and is given also right axis 21 22 00:03:39,200 --> 00:03:50,540 the blue line represents irradiance and equal to the area under spectrum power density. 22 23 00:03:50,590 --> 00:03:53,350 Up to the wave length lambda 23 24 00:03:56,740 --> 00:04:08,550 as illustrated if we integrate over the entire spertial power density the Blue Line corresponding 24 25 00:04:08,550 --> 00:04:16,320 to irradiance equal to 1000 watt/ square meter. 25 26 00:04:16,490 --> 00:04:25,790 Note that 1000 watt /square meter is equal to . 26 27 00:04:25,840 --> 00:04:29,200 100millions Watt per centimeter. 27 28 00:04:29,690 --> 00:04:38,040 So don't be confused when you are reading in some books with the standard 28 29 00:04:38,130 --> 00:04:47,790 Test irradiance of one hundred million watt per square centimeter. 29 30 00:04:47,930 --> 00:04:59,220 The second thing we are going to talk about is the solar irradiance even so it is so so many technical advancement 30 31 00:04:59,670 --> 00:05:05,700 are being made at the cell level to improve the efficiency. 31 32 00:05:05,700 --> 00:05:14,290 As discussed there is is still a lot to be done and there PV system level to ensure the healthy. 32 33 00:05:14,290 --> 00:05:16,070 PV yield. 33 34 00:05:16,970 --> 00:05:30,300 Getting a good module in terms of efficiency and the output since 50s is way only a half of the battle but what's 34 35 00:05:30,570 --> 00:05:34,800 matter is the yield of the power system. 35 36 00:05:34,800 --> 00:05:48,000 So the question is what else can you do to increase the yield of your PV system at the system level. 36 37 00:05:49,130 --> 00:06:02,180 Of course MPP tracking or MPPT as MPPT is a valuable tool to ensure the PV module always 37 38 00:06:02,240 --> 00:06:05,700 operated as the MPP point. 38 39 00:06:07,950 --> 00:06:15,170 On IV curve under a given set of irradiance and temperature. 39 40 00:06:15,560 --> 00:06:22,150 But how do we improve the amount of light falling on the PV. 40 41 00:06:22,150 --> 00:06:38,350 model at the system level the simplest way of doing that is by playing with the orientation and tilt 41 42 00:06:38,710 --> 00:06:39,850 of the module. 42 43 00:06:42,260 --> 00:06:46,200 What do we mean by orientation and tilt. 43 44 00:06:46,370 --> 00:06:55,100 tilt is the degree of freedom that defines the elevation or the pitch of solar module with the respect to 44 45 00:06:55,100 --> 00:06:57,780 the horizontal axis. 45 46 00:06:57,870 --> 00:07:09,240 Of course this seems from a basic fact that in order to get maximum energy from the sun at any moment 46 47 00:07:09,540 --> 00:07:21,720 the plane of solar panel or the plane of the array as sometimes called should be perpendicular to 47 48 00:07:21,720 --> 00:07:26,490 the direct rays of the sun. 48 49 00:07:26,490 --> 00:07:38,220 at this moment the amount of solar energy falling on the earth depend on some astronomical factors like 49 50 00:07:38,640 --> 00:07:45,990 the tilt of the earth's axis and the near spherical shape of this earth. 50 51 00:07:46,840 --> 00:07:49,330 But this is not our case. 51 52 00:07:50,780 --> 00:08:00,800 So in general all as a parameter being unchanged higher in radians greater output power's generated. 52 53 00:08:01,580 --> 00:08:15,470 So you need to change the tilt angle of the PV module as shown to get higher irradiance during the whole 53 54 00:08:15,470 --> 00:08:16,550 year. 54 55 00:08:16,550 --> 00:08:28,850 So you need to change the tilte angle of PV module to get higher energy during the whole year. 55 56 00:08:35,520 --> 00:08:38,400 So this is the end today. 56 57 00:08:38,400 --> 00:08:40,710 See you in the next block.