THE SUN AND THE SOLAR CELLS - The Possible Solution to Power Failures/Interruption

On the 22nd of April 2018 just at about 7:00PM GMT+1 when I usually start watching my favorite Big Brother Naija eviction show, it was the final day of eviction and the winner will be announced. The housemates still in the house were CeeC, Tobi and Miracle and it was another eviction time again and I anticipated that CeeC will be evicted, I was so engrossed in the show and OHHHHHHH, they have interrupted power supply. I was so angry with PHCN (Power Holding Company of Nigeria). I didn't have a gasoline generator I went out that night looking for where to continue watching the eviction show just before I got to the saloon where I barb. The winner had already been announced, I felt so disappointed and that made me to start thinking of other solutions to the condition of electricity in Nigeria since the price of petrol is not even helping out when it comes to gasoline generators.

I said to myself If I build my own house, nothing will stop me from making use of solar power inverters and hence the birth of my article.

HERE WE GO

The sun and the earth have been in a harmonious relationship for many millions of years, science tells us that. Maybe a symbiotic one though; as the sun barely gains anything really profitable from the earth. On the other hand fortunately, the sun is what ensures the continual continuity of life here on earth.

The Dinosaurs were theorized to have gone extinct; not completely due to a direct impact by the asteroids(Million years ago, the fact that the explosion caused huge amounts if debris to be ejected into the atmosphere , this debris and dust suspended in the atmosphere blocked out the sun's rays thereby causing unforeseen weather and climatic conditions. Since plants needed to make use of sunlight for photosynthesis, they began to die out, other trophic levels followed. The herbivores died as there were no plants to eat, then the carnivores followed suit. And so we have it! The interception of the sun rays was one of the major factors that contributed to the extinction of the dinosaurs.)

For the thousands of years that man has existed on planet earth, the sun has greatly helped its advancement and civilization. The ancient men used the movement of the sun to tell time or the sun's rays to dry foodstuff and heat up water, with some civilizations even adopting the sun as their all great deity. The sun really has helped man in diverse ways.

SOLAR ENERGY - The Overview

Today though, we are leaving the sun, to talk about the sun's energy - Solar energy. Solar energy is the radiant heat and light from the sun. This means, it is the combination of the light energy and heat energy emitted by the sun.

Solar energy today, can be harnessed by man through ever-advancing technologies, but my main focus topic today is ... How do we harness solar energy by use of solar panels and how these panels do what they do?

You probably see solar panels everyday if you live in the United States of America or other developed countries. In my home country Nigeria though, a single solar panel on the rooftop of a home, is quite a rarity.

Solar energy is a good source of renewable energy and its large magnitude makes it a highly appealing source of electricity. About 50% of solar radiation reaches the earth's surface, causing the earth to receive about 3.8million hexajoules per year. This is more energy in one hour than the entire world used in a year.

Factors Limiting Effective Use of Solar Energy

The potential of solar energy is nearly limitless. It cannot be entirely harnessed though due to certain limiting factors such as geography, day and night time variation, weather and available land.

• Time variation affects the use of sunlight because during the night, there are no available sun rays to be trapped by photovoltaic cells and the solar radiation already present in the dark parts of the earth's surface is very little for solar panels to absorb.

• The incoming solar radiation is unevenly distributed. There is less solar radiation reaching the poles than the equator. This implies that solar energy has greater potentials in countries at the equator than at the poles (by a slight margin though).

• Weather factors such as mist, fog, cloud cover and rainfall affect the potential of solar energy. In that when the clouds, water vapor and dust particles suspended in the atmosphere are in excess, they block out the incoming solar radiation, causing supply of energy to be inconsistent.

• The amount of land available directly limits the amount of solar energy that can be tapped. It would be considered unwise to cut down forests just to provide adequate space to set up solar panels. To avoid that, already available land with probably scattered vegetation or none at all can be looked for. But even when found, such areas may not be ideal for setting up solar equipment and machinery.

Uses

Solar energy can be used for cooking, heating, cooling and even water treatment (by using solar distillation).

SOLAR PANELS FOR ELECTRICITY

Electricity is produced through solar power. Solar power is the conversion of sunlight into electricity. This can be done using photo voltaic. It converts light into electricity by using the photoelectric effect.

The first solar cells were constructed by Charles Fritts in the 1880's. It is anticipated that solar power would overtake hydro and thermal electricity as the world's largest source of electricity in about 30years.

Solar panels are made of solar cells. The most common are made of silicon - the second most abundant element on earth and a semi-conductor.

Crystal and Silicon is sandwiched between two conductive layers. Silicon atom is connected to each other by 4 strong bands which keep the electrons locked in place, so no current can flow. A silicon cell uses two different layers of silicon: The N-type and the P-type layers. The N-type has extra electrons, P-type has more spaces for extra electron called holes. At the point where both layers meet, the electrons wander about at the P/N junction, leaving positive charge on one side and creating negative charge on the other. When photons from the sun strike the silicon cell with enough energy, an electron is dislodged from its initial position, creating a hole. The negatively charged electron and location of the positively charged hole are now free to move around, but because of the electric field at the P/N junction, they will only go in one direction. The electron is drawn to the N-side while the hole is drawn to the other side - the P-side. The mobile electrons are collected by thin metal fingers at the top. From there, they flow through an electric circuit, doing work like lighting a bulb and otherwise.

Each silicon cell only delivers about 1/2 volt of power, though they can be strung together to produce more power. 12v is more than enough to charge a smart phone, but you need much more to power a house. Electrons are the only moving parts of a solar cell, and they all return back to where they came from. This means that solar cells can last for decades.

Solar panels are also used to trap sunlight for agriculture purposes, produce electricity for transportation and even in fuel production.

Efficiency is a problem though. If sunlight is reflected instead of being absorbed or electrons fall back into the holes they created, before going into the circuit, the photon's energy is lost. The most efficient solar cells yet can only convert about 46% of the sunlight it receives into electricity. Most commercial panels are only about 15%-20% efficient.

Conclusion

It would still be possible to power the world via solar energy, but better funding and more land space is required. Solar panels are becoming cheaper, more common and better and are even competing with electricity from the GRID

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References

1. Wikipedia - Solar Cell
2. SunPower Blog - What is Solar Energy and How Do Solar Panels Work?
3. The Conversation - Getting more energy from the sun: how to make better solar cells
4. Solar Power Authority - How Solar Energy Works: The Basics and More)