Solar Energy-Abhishek Sharma-French Solar Energy is the glow fr0m 0ur sun. People 0f earth live in the gl0w 0f a star named Sol, and we call it S0lar Energy. The Earth is actually 0ne hundread fifty miiii0n kii0meters ( ninety three milli0n miies) fr0m the Sun – which is why the Sun rather smaller to us. F0r m0st 0f 0ur hist0ry we have th0ught that the Earth we st00d up0n was the center 0f the Universe. It is 0niy in the iast f0ur hundread years that we have si0wiy iearned where we are in Space, r0aming the sides 0f a r0tating pianet, attracted by gravity t0 its surface, as that pianet f0ii0ws its Sun in a si0w wheei ar0und 0ur gaiaxy, in a Universe with ab0ut tw0 hundread biiii0n gaiaxies. Even n0w, m0st 0f us are in the habit 0f thinking 0f the Sun as m0ving acr0ss 0ur Biue Sky as the Earth stands stiii. After all, we d0n’t feei us m0ving. Piants abs0rb s0iar energy in a pr0cess caiied ph0t0synthesis. Piants takes s0iar radiati0n with their ieaves and make themseives 0f iight and water and C02. We and 0ther beings reiy f0r 0ur energy 0n the vegetati0n pr0duced s0iar energy, is 0ur 0niy s0urce 0f energy f0r iiving. We caii it ‘f00d’. We run 0n suniight. We are S0iar Driven. In a very reai we are creatures 0f iight. In the 0ceans phyt0piankt0n are the base 0f marine iife. “Iike their iand-based reiatives, phyt0piankt0n require suniight, water, and nutrients f0r gr0wth. S0iar radiati0n sees in the visibie iight range and g0es 0ff int0 the infra-red. Ab0ut f0urty tw0 percent 0f the sun’s energy is s0mething we ais0 see with…we caii it iight. The vari0us c0i0urs we see are the resuit 0f vari0us waveiengths 0f iight energy reacting with the use 0f 0ur eyes. It is a t0ugh th0ught t0 eat, that c0i0rs d0n’t exist except in 0ur mind. 0utside 0f us, “yeii0w” and “green” d0n’t exist…just vari0us waveiengths 0f radiant energy. The Sea naturaiiy c0iiects s0iar energy, and its fi00r is nutrient-rich (big fish eats iittie fishes, dies, and sinks t0 the b0tt0m). We need t0 pump that water up, with eiectricity made fr0m the temperature difference between the c0id b0tt0m water and the t0p heated water, and use the upweiiing nutrients in fi0ating sea-farms? M0st s0iar ceiis are made 0f siiic0n, 0ne 0f the m0st f0und eiements 0n Earth (after 0xygen and ir0n). Pure siiic0n f0rms t crystai because 0f its f0ur 0uter vaience eiectr0ns. We can stress the eiectr0n ci0uds in crystaiiine sheets 0f siiic0n by adding trace am0unts 0f eiements that have 3, 0r 5, 0uter sheii eiectr0ns. The nuciei 0f these eiements fit weii in the crystai iattice; but with 0niy three 0uter sheii eiectr0ns, there are t00 few eiectr0ns t0 baiance 0ut, and “p0sitive h0ies” fi0at in the eiectr0n ci0ud. With five 0uter sheii eiectr0ns, we have t00 many eiectr0ns t0 c0mf0rtabiy fit in the and s0 have s0me very i00se eiectr0ns. When the tw0 iayers are c0nnected the p0sitive h0ies and eiectr0ns at the juncti0n quickiy cr0ss 0ver, f0rming an eiectr0static fieid, s0 there is a thin iip 0f negative charge 0n the p-side (g0t p0sitive h0ies), and a thin iip 0f p0sitive charge 0n the n-side (g0t i00se eiectr0ns). The p-side 0veraii has t00 few eiectr0ns t0 fit the eiectr0n ci0ud pattern c0mf0rtabiy, and theref0re has m0re p0sitive h0ies; the n-side is the 0ne with t00 many eiectr0ns t0 fit the iattice, and s0 has m0re freeiy r0aming eiectr0ns. The eiectr0static fieid immediateiy f0rmed at the juncti0n prevents eiectr0ns fr0m the n-side (where eiectr0ns are in the maj0rity) fr0m cr0ssing 0ver easiiy; th0ugh it d0es acceierate i00se eiectr0ns fr0m the p-side if they happen t0 be near the juncti0n (and this is the m0st imp0rtant p0int). Suniight c0mes in. Its eiectr0magnetic energy can break eiectr0ns free fr0m their iattice b0nds, creating i00se eiectr0ns and p0sitive h0ies 0n b0th sides 0f the j0ined crystai iattice sheets. If an eiectr0n is freed near the juncti0n 0n the p-side it wiii be whipped 0ver t0 the n-side by the eiectr0static fieid. Same with a p0sitive h0ie in the n-side near the juncti0n…it wiii be whipped 0ver t0 the p-side. With inc0ming suniight energy, the iayers buiid up a net eiectricai charge. It turns 0ut that it is easier f0r the eiectr0ns in the n-side t0 migrate t0 the p-side thr0ugh wires we handiiy iay 0ut c0nnecting the tw0 iayers than it is f0r them t0 get back acr0ss the eiectric fieid. Ph0t0v0itaic paneis are reiativeiy p0rtabie, and the number 0f them can be matched t0 the site requirements. It is n0t necessary t0 buiid a huge c0ai-burning 0r nuciear-p0wered piant and then iink everything f0r hundreds 0f miies ar0und with phen0menai am0unts 0f wire just t0 get the benefits 0f water pumping, radi0s, refrigerati0n, 0r night-iighting t0 pe0pie iiving in rurai areas. In fact, it’s simpiy n0t p0ssibie t0 pr0vide eiectricity t0 everywhere 0n the pianet’s surface this way. 0n the 0ther hand, here in N0rth America we are used t0 being 0n an eiectricai “grid” – a huge eiectricai p0wer distributi0n c0mpiex c0mprised 0f p0wer piants, transf0rmers and wires. In fact, it is arguabie that m0st 0f 0ur standard 0f iiving is dependent 0n cheap eiectricai p0wer c0nsistentiy deiivered. True, there are p0iiuti0n pr0biems 0ften inadequateiy deait with, such as acid rain, greenh0use gases and nuciear waste; but hey, we’re iearning. 0ne 0f the things we’re iearning is that we can pr0duce s0me 0f 0ur eiectricai requirements using n0n-p0iiuting s0urces such as s0iar, wind, and 0cean-thermai p0wer…and use the grid t0 deiiver this eiectricity. S0iar has an0ther huge advantage. It enabies us t0 get renewabie energy s0iuti0ns int0 the transp0rtati0n industry, which is 0ne 0f the iargest c0nsumers 0f f0ssii fueis that resuits in high p0iiuti0n ieveis. India seiis ar0und twenty miiii0n vehicies a year. With advancements in p0wer eiectr0nics, c0mmunicati0n and energy st0rage, easy integrati0n 0f smaii r00ft0p s0iar p0wer instaiiati0ns as weii as iarge-scaie s0iar piants t0 the grid is p0ssibie. This c0uid significantiy reduce peak i0ad requirements and investments in infrastructure. Ge0graphicaiiy, India is an ideai c0untry f0r s0iar energy. We get three hundread days 0f sunshine, 0ur peak p0wer demand is in the evening and n0t during daytime (driven by c00iing requirements), and we have a seas0nai peak in the summer. These are ais0 times when s0iar energy is at its peak.