1 00:15:06,140 --> 00:15:07,280 Hello again. 2 00:15:07,640 --> 00:15:09,800 In the next video in the series, we're going to talk about 3 00:15:10,360 --> 00:15:12,860 energy from the Sun 4 00:15:12,860 --> 00:15:14,760 in the use of solar panel. 5 00:15:14,760 --> 00:15:15,980 Two types of solar panel. 6 00:15:15,980 --> 00:15:19,280 There are solar PV photovoltaic and there are 7 00:15:19,280 --> 00:15:22,120 thermal people do get the two confused. 8 00:15:22,420 --> 00:15:27,580 In essence, the Sun produces particles of pure energy 9 00:15:27,580 --> 00:15:32,040 these are called photons when it turns hydrogen into helium. 10 00:15:32,380 --> 00:15:35,280 We all know E=MC2 So matter 11 00:15:35,280 --> 00:15:38,200 and energy are transferable. 12 00:15:39,340 --> 00:15:41,380 A little photon shoots out of the sun. 13 00:15:42,400 --> 00:15:43,100 Massless. 14 00:15:43,100 --> 00:15:45,280 There is no weight at all. 15 00:15:45,280 --> 00:15:48,480 Well, weight, mass there is no mass at all to a photon 16 00:15:48,480 --> 00:15:51,700 it's a massless particle flies through space. 17 00:15:51,700 --> 00:15:54,760 Hits the surface of the Earth warms us up. 18 00:15:55,060 --> 00:15:57,020 We capture those photons. 19 00:15:57,020 --> 00:16:02,380 We use them to shift electrons about now in a photovoltaic panel. 20 00:16:03,020 --> 00:16:08,020 There are two layers separated by a layer. 21 00:16:08,720 --> 00:16:11,000 A photon hits an electron. 22 00:16:11,320 --> 00:16:13,360 It pushes it through. 23 00:16:13,360 --> 00:16:15,740 The semiconductor layer goes onto the other side. 24 00:16:16,040 --> 00:16:20,060 All that does is create what is called potential electrical 25 00:16:20,060 --> 00:16:23,060 potential, electric potential is measured in volts it is just a pressure. 26 00:16:23,480 --> 00:16:25,940 We've got too many electrons on one side. 27 00:16:25,940 --> 00:16:26,900 They want to come back 28 00:16:27,880 --> 00:16:29,900 and form equilibrium. 29 00:16:30,260 --> 00:16:32,620 They do that and the electricity flows 30 00:16:33,100 --> 00:16:36,640 they run around the wire, and they come back, forming 31 00:16:38,380 --> 00:16:39,280 electricity. 32 00:16:39,280 --> 00:16:41,900 You're taking pure energy from the sun. 33 00:16:41,900 --> 00:16:44,240 You are moving electrons, 34 00:16:45,280 --> 00:16:47,560 causing pressure differential. 35 00:16:47,560 --> 00:16:51,040 So photovoltaic cells come in many different types. 36 00:16:51,040 --> 00:16:53,800 I'm going to talk about monocrystalline and polycrystalline. 37 00:16:53,800 --> 00:16:56,480 Monocrystalline cheap to produce. 38 00:16:56,680 --> 00:16:59,760 Not quite as efficient polycrystalline. 39 00:16:59,760 --> 00:17:01,520 More expensive to produce. 40 00:17:01,520 --> 00:17:02,560 A lot more efficient. 41 00:17:02,560 --> 00:17:05,620 Now, the efficiency of photovoltaic cells in the last few years 42 00:17:05,900 --> 00:17:07,560 has gone through the roof. 43 00:17:07,560 --> 00:17:10,240 They used to be 12% efficient. 44 00:17:10,240 --> 00:17:12,840 Now reaching up to 26-27% 45 00:17:12,840 --> 00:17:15,760 some of the ones that have been developed for use in space. 46 00:17:16,240 --> 00:17:17,460 Very expensive. 47 00:17:17,460 --> 00:17:19,600 But that technology we are using 48 00:17:20,740 --> 00:17:24,100 now and finding cheaper ways to produce them 49 00:17:24,560 --> 00:17:27,820 and using that to make them more and more efficient. 50 00:17:28,300 --> 00:17:31,180 The other type of Solar System. 51 00:17:31,180 --> 00:17:34,660 Solar cell is a thermal solar thermal. 52 00:17:35,240 --> 00:17:40,000 You will see these on domestic settings more than you will anywhere else. 53 00:17:40,280 --> 00:17:44,900 The photovoltaic panels we can use on solar farms. 54 00:17:45,200 --> 00:17:47,440 I'm sure some people have seen them driving around the country. 55 00:17:47,760 --> 00:17:51,740 You'll just see a field covered in photo voltaic cells. 56 00:17:51,940 --> 00:17:55,280 They produce electricity on a massive scale. 57 00:17:55,960 --> 00:17:58,720 Put them on the roof of your house domestic setting. 58 00:17:58,900 --> 00:18:01,100 Again, same principle. 59 00:18:01,100 --> 00:18:03,740 Thermal cells have tubes inside the tubes. 60 00:18:03,820 --> 00:18:06,040 There is a gas or liquid under pressure. 61 00:18:06,840 --> 00:18:09,400 This gas or liquid takes those photons 62 00:18:10,420 --> 00:18:11,860 because they were under pressure. 63 00:18:11,860 --> 00:18:14,740 They can heat the cells to extremely high temperatures. 64 00:18:15,080 --> 00:18:16,640 They really, really can. 65 00:18:16,640 --> 00:18:20,180 That temperature differential is then carried to 66 00:18:20,320 --> 00:18:23,200 an exchanger, a heat exchanger. 67 00:18:23,200 --> 00:18:26,540 You put water through the heat exchanger. 68 00:18:27,040 --> 00:18:29,620 You can actually get it to turn to steam, 69 00:18:29,620 --> 00:18:31,040 obviously in the domestic setting. 70 00:18:31,040 --> 00:18:32,480 That's not what we want. 71 00:18:32,680 --> 00:18:34,360 It will run your heating. 72 00:18:34,360 --> 00:18:38,200 It will alleviate the need to actually burn gas in a boiler. 73 00:18:38,560 --> 00:18:40,360 So therefore, 74 00:18:40,760 --> 00:18:42,840 if we all use thermal 75 00:18:43,360 --> 00:18:47,000 cells, the use of gas as a domestic 76 00:18:47,500 --> 00:18:50,740 heating fuel would drop a lot. 77 00:18:50,760 --> 00:18:54,320 Now, unfortunately, because we live in the northern hemisphere, we don't 78 00:18:55,060 --> 00:18:58,000 receive as much energy from the Sun as anybody. 79 00:18:58,360 --> 00:19:02,380 Further south, so the further south you get towards the equator the better it is. 80 00:19:02,380 --> 00:19:07,700 But even on dull days, even on overcast days, there are still photons. 81 00:19:07,880 --> 00:19:11,380 We know there's still photons coming because we can see there is light. 82 00:19:11,560 --> 00:19:13,720 Those photons can still do work. 83 00:19:14,060 --> 00:19:16,680 We can still use them to produce electricity. 84 00:19:17,000 --> 00:19:20,720 We can still use them to heat up liquids and gases 85 00:19:20,920 --> 00:19:25,760 to form a useful energy system for our homes.