WHAT IS SOLAR ENERGY AND WHY USE SOLAR ENERGY?
The sun’s atmosphere - also called the corona- boils at about a temperature of 1-Million-degree Kelvin. We humans have heated matter to an astonishing 3.6 million degrees Celsius. But that was under experimental conditions, and with the help of insanely expensive machinery (By expensive, I mean the world’s most powerful X-Ray laser machine). The sun produces an insane amount of energy, because of its high temperature. The sun has a mass-energy conversion rate of about 4.26 million metric tons per second, which produces the equivalent of 38,460 septillion watts (3.846×1026 W) per second. To put this into perspective, you would require about 18 billion thermonuclear bombs exploding per second to produce that kind of energy. (FUN FACT- The sun’s atmosphere is actually hotter than its surface. The exact reasoning still remains a mystery. Although, there are some theories floating around, none has yet explained comprehensively this observation)
Solar energy, if harnessed efficiently, is the single most valuable renewable source of energy for earthlings. The first ever solar cell was not built until the 1940’s. However, solar energy has always been utilised by humans in one way or another. In the ancient times, solar energy was used by magnifying glasses in order to light fires. It is believed that the Romans and the Greeks used big mirrors to harness solar energy and light torches for ceremonies and other occasions. The point being that although, humans started using solar energy to produce electricity in only the nineteenth century, it has always been an important source of energy for humans.
Coming back to the modern era, let’s see what role solar energy plays for humans today.
There are many different ways of producing energy. As you already might be aware, there are two types of energy sources i.e., renewable and non-renewable energy sources. The renewable ones are the ones which never get exhausted and are provided in unlimited quantity by the nature. One of the most advanced type of renewable energy is the one generated with the help of turbines. The turbine is a rotor, connected to a much larger generator, which produces electricity in bulk. The turbine may be rotated in several different ways, which gives rise to many different types of electricity production departments- steam, geothermal, wind, hydroelectric, wave, tidal, and nuclear.
By far, the BEST method of using the nature to produce electrical energy through heat and light is solar energy, which is the topic of this post.
But, how do we use this solar energy to produce electricity?
COMPONENTS OF A TYPICAL SOLAR PANEL
The answer is photovoltaic/ solar cells. A solar cell is the very basic component of a solar panel, which is nothing but a series connection of a bunch of photovoltaic cells. Each one of these cells can produce up to 8 ampere current. The series string is then laminated and connected to a backing material, covered with a waterproof sheet, and sealed with glass material. These panels are then put into an array, which is the form of these photovoltaic cells that you might have seen on the roof of houses. Just like the cells were connected in series to produce the maximum possible current, these panels are also connected in series, which gives the maximum current and voltage output.
TYPES OF SOLAR PANELS
Different materials may be used to make the solar panel that we talked about in the last paragraph. The most industrially common material is silicon, which is also one of the most efficient ways of harnessing solar energy.
The silicon material itself, can be used in different ways to produce different quality panels. The most basic one is the one made out of amorphous silicon; It is the most basic solar panel, mainly used for prototypes- only going up to an efficiency of about 10 percent. The solar panel made of polycrystalline silicon is the most industrially dominant, going up to an efficiency of about a 17 percent.
Now let’s analyse the structure of the cross section of a photovoltaic cell.
As you can see in the figure, there are two separate junctions – N type and P type. Well, don’t panic, p for positive and N for negative. Let me explain this. Silicon material is dopped with different materials in order to change its conductivity. Well, the p layer would contain a positive charge and the n type, negative. These charges would help proper conductivity of electricity generated by silicon, and this completes the circuit. NOW YOU KNOW !!
AN INTRODUCTION TO SBSP(space based solar power)
We now arrive at the most interesting part of the post i.e. space based solar Power. Until now, we talked about harnessing solar energy on our own planet. Well, about 47% of sun’s energy is lost on its way to earth. This might seem a weird phenomenon to some of you high school students out there; how can energy be lost into thin air (which btw is not present in space) ? Well, this energy is not really lost. Most of it is deflected back into the space by the Earth’s atmosphere, whereas the rest of it is absorbed by the innumerable gases present in Earth’s atmosphere. If this “barrier” of our planet’s atmosphere was somehow broken, it would mean that this energy would no longer be deflected back and we would be able to harness all of it. But, how do we do that?
The solution is SBSP. SBSP is the idea of sending satellites equipped with photovoltaics, so that we would be able to harness a much larger amount of solar energy than we are at Earth. SBSP is open for research. Many physicists believe that SBSP is the future of renewable energy sources. But, nothing comes without a flaw.
THE FLAWS OF SOLAR ENERGY
Solar energy is very expensive for many, and developments are being made in order to maximize the efficiency and minimize the cost of photovoltaics. Many other kinds of materials are being tested, and solar energy is a growing department of physics.
As far as SBSP goes, it is a great topic of research, but a concept of the future. As of right now, it many just be way too expensive to be of any economical importance. For deep space projects, solar energy is no longer being used because of darkness in many undiscovered areas of space. In the perseverance, NASA chose the MMRTG(multi-mission radioisotope thermoelectric generator ) over solar energy, which tells us a lot about the future of space exploration projects.