Understanding Solar Electricity_ The Sun, the Panel and Photoelectric Effect

The sun is the main source(the generator) of energy of almost all the forms of energy in the ecosystem . according to the second law of thermodynamics, energy can be converted form one form to the other, ideally the magnitude of energy radiated by the sun to the earth should be equal to the total energy(energy from the sun) present on earth, but losses exist. The sun transmits energy in beams of light to the earth through radiation, the magnitude of this energy that successfully reaches the earth is significantly lesser than the initial energy transmitted by the sun due to heat losses. The energy now on earth is used for photosynthesis by plant, to keep the earth warmth, harnessing to electricity and other vital functions that have made the earth a solace.

Photoelectric Effect

Over decades ago, scientist has been in a consistent mission to rescue the earth from global warming. In their success-step to this aim, they invented other safe alternatives for generating electricity. Scientists studied the sun and found possibilities of solar electricity. The energy(photon) radiated from the sun via beams of light per minute is more than the sum of electric energy generated globally every year. Scientists also knew that the only way to harness solar energy into electricity is utilizing the photoelectric effect of light(particle property of light).

Max Planck made a hypothesis and he showed that heat or electromagnetic radiation was emitted from hot bodies(sun is also a hot body) in little packets which he called quanta, he proposed that the energy content of these quantum is inversely proportion to its wavelength. Later, Albert Einstein developed Planck's concept and came out with photoelectric effect. He proposed that light radiates small discrete particles or packets of energy which he called photons. Photoelectric effect is the particles property of light in which if light is incident on an photoemissive material(metals or metalloids), its photons collides with the atoms of the material and knocks out electron from the surface of the material. These ejected electrons from the photoemissive material have different kinetic energy which is dependent on the frequency of incident light(E=h/f)

As stated previously, sunlight radiates photon(photons are not continuous energy value but granular or in discrete units and is dependent on the radiation frequency) of high magnitude of energy which is higher than the work function of photoemissive materials. At this point, photons from sunlight is present, the photoelectric effect of light with certain materials is known. However, a designed material that can give absorb light and gice out electrons when light is incident on it(photoemissive material) was needed, this was where the idea of solar panel began.

Solar Panel Technology

Solar panel is basically an assembly or array of solar cells interconnected to each other using a tiny conductor(mostly copper). Solar cell or photovoltaic cell is a cell made of of material(doped semiconductor) which its electrical characteristics(current and voltage) varies with light. The higher the intensity of the incident light, the higher the quantity of electrons emitted and the higher the frequency of incident light, the higher the kinetic energy of ejected electrons. After interconnection of the solar cells, it is enclosed in a glass_ all this assembly is called solar panel. A conductor is extended from the solar panel and the electrons knocked out from the assembly of solar cells flows through the conductor. Hence creating electricity_ the flow of electrons.

Presently, the efficiency of solar pane is ranges from 20-40%, this means that only 20-40% of the sunlight(photon energy) incident, is absorbed by the panel and is converted into electricity, the remaining percentage is reflected off by the solar panel. However, with time the efficiency would be above 60% because solar electricity technology is progressive.

The Battery And The Charge Control System

The flowing electrons ejected from the solar panel need to be stored and used in the appropriate time. For this cause an electrical storage is include in the solar electricity technology. The electrons flow from the panel through a conductor connected to a battery, this electrical energy is converted to chemical energy by some chemistry reactions (this is the basis of rechargeable batteries). A charging control system is adopted to avoid overcharging which might lead to damage of the battery. This system regulates the charging current and automatically stops the charging process once the charge is completed.

Conclusion

The sun radiates sachets of energy which collides with the atoms of solar panel and knocks out electrons from it. The knocked out electrons flow(electricity) through the conducting wire and charges the battery connected at its terminals. The quantity of ejected electron and its kinetic energy depends on the intensity and frequency of the incident light respectively, more electrons flowing with high velocity results to higher voltage or current. This is the reason why solar batteries charge faster during afternoon periods.
Finally, the energy cycle of solar electricity is photon energy is transformed to electrical energy by the solar panel, this electrical energy is converted to chemical energy by the rechargeable battery. This is in accordance with law of thermodynamics_ energy can not be created or destroyed, rather, are transformed form one form to the other.

Thanks for your ample time, I remain your brethren @ikchris

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References

• James Maclachian, Children of Prometheus(A history of science and technology): Quanta and photons
  ISBN: 0-921332-27-0
• John O.A. Odiddi, Mechanics, Thermal Physics and Properties of Matter: Heat transfer_Radiation
• M. Nelkon, Principles of Physics: Emission Of Electromagnetic radiation
• G.I Brown, Introduction to Physical Chemistry: Law of thermodynamics
• The solar panel

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