Solarni panel (korišćenje sunčeve energije)
Sunce je daleko najveći izvor energije u solarnom sistemu. Količina sunčeve energije koja svaki minut stiže na Zemlju dovoljna je da zadovolji godišnje energetske potrebe čovečanstva u trenutnoj fazi razvoja. Uprkos ogromnom potencijalu, iskorišćenje pomenute energije trenutno pokriva vrlo mali procenat energetskih potreba čovečanstva. Razlozi su opravdani, sa jedne strane slaba razvijenost trenutnih tehnologija za iskorišćavanje energije Sunca, a sa druge strane visoka cena gotovih uređaja za upotrebu solarne energije.
Postoji nekoliko načina eksploatacije energije Sunca. Najjednostavniji i najjeftiniji način iskorišćavanja solarne energije svakako je grejanje vode ili neke druge tečnosti za upotrebu u domaćinstvima. Elementi koji koriste energiju Sunca za grejanje vode nazivaju se solarni kolektori i uobičajeno se postavljaju na krovove kuća i zgrada.
Drugi način iskorišćenja energije Sunca je koncentrisanje solarne energije pomoću sistema ogledala i stvaranje velike količine toplotne energije koja se kasnije u standardnim uređajima pretvara u električnu energiju. Ovako zamišljena postrojenja mogu biti vrlo velika i uobičajeno se grade u pustinjama, a služe za komercijalnu proizvodnju električne energije. Fotonaponske ćelije su treći i najpoželjniji način iskorišćavanja energije Sunca, ali zbog slabe efikasnosti i visoke cene ne koriste se još uvek u velikoj meri. Fotonaponski efekat otkrio je francuski fizičar Alexandre-Edmond Becquerel (1820-1891). 1839 godine. Fotonaponske ćelije direktno pretvaraju solarnu energiju u električnu energiju. Fotonaponske ćelije uobičajeno se koriste tamo gde nije moguće dovesti neki drugi izvor energije, na primer na satelitima, na znakovima uz puteve i slično. Dodatno se koriste za napajanje energijom malih potrošača, na primer džepnih digitrona.
PRINCIP RADA Fotonaponske ćelije izgrađene su od dva sloja-pozitivnog i negativnog, a razlika potencijala između ta dva sloja zavisi od intenziteta solarnog zračenja. Solarna energija stiže na Zemlju u obliku fotona. Prilikom pada na površinu solarne ćelije ti fotoni predaju svoju energiju panelu i na taj način izbijaju negativno naelektrisane elektrone iz atoma. Izbijeni elektroni kreću se prema drugoj (negativnoj) strani panela i na taj način dolazi do razlike potencijala, to jest nastaje električna energija. Fotonaponske ćelije se grade od silicijuma, a silicijum je jedan od najzastupljenijih elemenata na Zemlji.



Solar panel (utilization of solar energy)

The Sun is by far the greatest source of energy in the solar system. The amount of solar energy that reaches the Earth every minute is enough to satisfy the annual energy requirements of the mankind at the current stage of development. In spite of the immense potential, the exploiting of the aforementioned energy at the moment covers avery small percentage of energy requirements of the human race. The reasons are justified: on the one hand, low level of development of current technologies for harnessing the energy of the Sun, and on the other hand high price of finished devices for the use of solar energy.

There are several ways of exploiting the energy of the Sun. The simplest and the cheapest way of utilizing solar energy is certainly water heating or the heating of some other liquid used in households. The elements which use the energy of the Sun for water heating are called solar collectors and they are usually set onto the roofs of houses and buildings.

The second way of utilizing the energy of the Sun is concentrating solar energy by means of the system of mirrors and creating a large amount of thermal energy which is later transformed intoelectrical energy within standard devices. The facilities designed in this way can be very large and they are usually built in the deserts, and they are used for commercial production of electrical energy. Photovoltaic cells represent the third and the most desirable way of utilizing the energy of the Sun, but due to the low efficiency and high price they are still not used to a large extent. Photovoltaic effect was discovered by French physicist Alexandre-Edmond Becquerel (1820-1891) in 1839. Photovoltaic cells transform solar energy directly into electrical energy. Photovoltaic cells are commonly used in situations when it is impossible to deliver some other source of energy, for example on satellites, road signs, etc. In addition to that, they are used for energy supply of small loads, such as pocket calculators.

THE METHOD OF OPERATION Photovoltaic cells consist of two layers–the positive and the negative one, and potential difference between those two layers depends on the intensity of solar radiation. Solar energy reaches the Earth in the form of photons. In the process of hitting the surface of the solar cell, those photons transmit their energy to the panel and in that way they knock negatively charged electrons out of the atom. Freed electrons move towards the other (negative) side of the panel and thus the potential difference is created, that is to say electrical energy is produced. Photovoltaic cells are made up of silicon, and silicon is one the most common elements on Earth.