Science & Technology: Solar Panel Technology: How it works, History and Development

Solar Panel Technology: How it works, History and Development

The universe contains millions of energy in it, but unfortunately new humans can use a small portion of natural energy. Examples of natural energy are sunlight that is used for technological developments in modern times, one of the uses of solar energy is solar sell technology or solar panels. With this solar panel you can produce electrical energy from sunlight.

Solar energy is energy in the form of light and heat from the sun. This energy can be utilized by using a range of technologies such as solar heating, solar photovoltaics, solar thermal electricity, solar architecture, and artificial photosynthesis.

Solar energy technology is generally categorized into two groups, namely passive utilization technology and active utilization technology. This grouping depends on the process of absorption, conversion, and distribution of solar energy. Examples of active use of solar energy are the use of photovoltaic panels and heat-absorbing panels. Examples of passive use of solar energy include directing buildings towards the sun, choosing buildings with good thermal mass or light dispersion capabilities, and designing spaces with natural air circulation.

How Does Solar Cell Technology Work?

Solar cells can be analogous to devices with two terminals or connections, where when the conditions are dark or not enough light functions like a diode, and when illuminated with sunlight can produce voltage. When irradiated, generally one commercial solar cell produces dc voltage of 0.5 to 1 volt, and short-circuit current in the milliampere scale per cm2. This voltage and current is not enough for various applications, so generally a number of solar cells are arranged in series to form a solar module. One solar module usually consists of 28-36 solar cells, and the total produces a dc voltage of 12 V under standard radiation conditions (Air Mass 1.5). These solar modules can be combined in parallel or in series to increase the total voltage and output current according to the power needed for a particular application. The picture below shows an illustration of a solar module.

Conventional solar cells work using the principle of p-n junction, i.e. junction between p-type and n-type semiconductors. This semiconductor consists of atomic bonds which have electrons as basic constituents. N-type semiconductors have excess electrons (negative charges) while p-type semiconductors have excess holes (positive charges) in their atomic structure. The condition of the excess electrons and holes can occur by doping the material with dopant atoms. For example to get p-type silicon material, silicon is doped by boron atoms, while to get n-type silicon material, silicon is doped by phosphorus atoms. The illustration below illustrates p-type and n-type semiconductor junctions.

The role of the p-n junction is to form an electric field so that electrons (and holes) can be extracted by contact material to produce electricity. When p-type and n-type semiconductors are contacted, the excess electrons will move from n-type semiconductors to p-type to form positive poles on n-type semiconductors, and vice versa negative poles in p-type semiconductors. As a result of the flow of electrons and holes, an electric field is formed which, when sunlight hits the juncture of the PN junction, will push electrons to move from the semiconductor to negative contact, which is then used as electricity, and instead the hole moves towards positive contact waiting for electrons to come, such as illustrated in the figure below.

In accordance with the development of science and technology, the types of solar cell technology also developed with various innovations. There are so-called one, two, three and four generation solar cells, with different structures or constituent cells. In this paper we will discuss the structure and workings of common solar cells in the market today, namely solar cells based on silicon material that also generally includes the structure and workings of first generation solar cells (silicon solar cells) and second (thin films).

The picture above shows an illustration of a solar cell and also its parts. Generally it consists of:

a. Substrate / Metal backing

Substrate is material that supports all components of the solar cell. Substrate material must also have good electrical conductivity because it also functions as a positive terminal contact for solar cells, so metal or metal materials such as aluminum or molybdenum are generally used. For dye-sensitized solar cells (DSSC) and organic solar cells, the substrate also functions as a place of entry of light so that the material used is conductive but also transparent materials such as tin tin oxide (ITO) and flourine doped tin oxide (FTO).

b. Semiconductor material

Semiconductor materials are a core part of solar cells that typically have thicknesses of up to several hundred micrometers for first generation solar cells (silicon), and 1-3 micrometers for thin layer solar cells. This semiconductor material serves to absorb light from sunlight. For the case of the picture above, the semiconductor used is silicon material, which is commonly applied in the electronics industry. Whereas for thin layer solar cells, semiconductor materials are commonly used and have entered the market, for example Cu (In, Ga) (S, Se) 2 (CIGS), CdTe (cadmium telluride), and amorphous silicon materials, in addition to semiconductor materials other potential in intensive research such as Cu2ZnSn (S, Se) 4 (CZTS) and Cu2O (copper oxide). The semiconductor part consists of a junction or a combination of two semiconductor materials, p-type semiconductors (the materials mentioned above ) and the n-type (n-type silicon, CdS, etc.) that forms the pn junction. This P-n junction is the key to the working principle of solar cells. The definition of p-type semiconductors, n-types, and also the principle of p-n junctions and solar cells will be discussed in the "how solar cells work" section.

c. Contact metal / contact grid

In addition to the substrate as positive contact, above some semiconductor material is usually overlaid metal material or transparent conductive material as negative contact.

d. Anti-reflective coating

Reflection of light must be minimized in order to optimize the light absorbed by the semiconductor. Therefore usually solar cells are coated with an anti-reflection layer. This anti-reflection material is a thin layer of material with a large optical refractive index between the semiconductor and air that causes light to be turned towards the semiconductor to minimize the reflected light back.

e. Glass encapsulation / cover

This section functions as an encapsulation to protect solar modules from rain or dirt.

History of Solar Panel Technology

Based on historical records, solar panel technology even existed in the 18th century, precisely in 1839 a French physicist named Alexandre Edmund Becquerel first sparked solar panel technology. Initially the solar panel technology was first coined by him through an experiment of irradiating two electrodes using various light spectra which produced a photovoltaic effect. Photovoltaic (Photo = light and voltaic = electricity voltage) is the process of forming electrical energy from light energy. But at that time, the amount of electrical energy produced was too little and easily exhausted.

In 1873, a scientist named Willoughby Smith discovered selenium which served as an element of photo conductivity. Bring a little fresh air and hope that light can produce energy can be realized.

Until in 1883 Charles Fritz tried to do research by coating selenium semiconductors with a very thin layer of gold. The photovoltaic it produces produces an efficiency of less than 1%.

Then in 1876, a teacher named William Grylls Adam and his student Richards Evans Day strengthened Alexandre Edmund Becquerel's research which suggested that in this world there are solid material objects, namely selenium which can produce electrical energy when selenium is exposed to certain rays. Although it only produces a small amount of electrical energy, this experiment also proves that electrical energy can be produced from light energy.

In 1904, Albert Einstein had researched solar sell and he named the experiment with the name Photoelectric Effect. It was only in 1941, researchers named Russell Ohl succeeded in developing solar panel technology while patenting the product. He is known as the first person to find solar cell technology (solar panels) and the use of homemade solar panels are still used today.

In making solar panels, he needed silicon. A solar panel can produce electricity because the semiconductor material in it is like silicon. When silicon is in direct contact with light, it can cause reactions that will later produce electrical energy.

Bell Laboratories succeeded in finding the right plate to be used as a base for the embryo of solar panels. Findings by Gerald Pearson, Daryl Chapin, and Sherher Fuller accidentally discovered that silicon combined with elements in the main metal produced by the extraction process turned out to be sensitive to light.

It is conceivable, how the struggles of the scientists above, with a long enough vulnerability of 115 years to find the initial milestone of solar panels that are now widely used in developed countries. The knowledge of the initial Scientists was passed on to the next generation and continued to the next generation and continues to do so until finally achieving good efficiency.

Development of Solar Panel Technology

Based on the latest data reveals that the earth is expected to experience an energy crisis in 2060 due to the depletion of petroleum. For this reason, researchers in today's age are competing to find alternative materials, one of them is by utilizing solar energy to produce energy.

Japan has even used solar panel technology since the 1980s or about 3 decades ago, then developed countries in Europe and America. The use of solar sell also penetrates in the automotive and gadget fields, for example the manufacture of solar power cars, mobilephone and solar power banks. Following is the development of the application of solar technology.

1. Home / Places with Solar Panel Power Technology

Passive home design specifically for humid and subtropical hot climates, a common feature of passive solar architecture is the direction of the building to the sun, the exact size of the building (ratio of surface area to small volume), barrier selection (porch), and thermal mass use. [ 20] When these features are shared, a bright room and comfortable temperature can be produced.

This greenhouse in the municipality of Westland, the Netherlands, is used to grow vegetables, fruits and flowers.

Solar water heaters face the sun to maximize absorption. The solar hot water system uses sunlight to heat water. In regions with low geographical longitude latitude (below 40 degrees), 60% - 70% of hot water for household use with temperatures up to 60 ° C can be obtained using a solar heating system

2. Solar Panel Power Vehicles

The presence of motorbikes and solar-powered cars adds to the list of technologies that utilize solar panels in this century. How not, now many car companies care about natural conditions by creating environmentally friendly cars. The main advantage of solar panel vehicles is to reduce the use of petroleum which is running low. In addition, this car is able to run continuously as long as it is in direct sunlight.

In 1974, the AstroFlight Sunrise drone made its first flight using solar power. On April 29, 1979, the Solar Riser made its first flight using solar power, with full control and capable of lifting someone up to 40 feet (12 m) in height. In 1980, Gossamer Penguin made its first solar-powered flight with a pilot powered only by photovoltaic cells. This flight was quickly followed by Solar Challenger that crossed the British canal in July 1981. In 1990, Eric Scott Raymond flew from California to North Carolina using solar power. The development of solar aircraft returned to the drone model with the Pathfinder model (in 1997) and subsequent designs, which produced the Helios model which managed to carve a record height for a rocketless aircraft at an altitude of 29,524 meters (96,864 feet) in 2001. Zephyr aircraft were developed by BAE Systems is the latest aircraft to break the record of solar powered flights, flying for 54 hours in 2007, and flights for a month are planned for 2010.

3. Solar Jacket

A new technological innovation has re-emerged, namely a solar power jacket that is capable of storing electrical energy from sunlight and can be used to charge smartphone batteries. For those of you who are on vacation and do not have time to bring a power bank or power bank is dead, you can use the second alternative by buying a solar power jacket.

With a capacity of up to 1,500 mAh, you can also charge your smartphone fully. The price of a solar power jacket is priced at around 7.2 million. Although you have to spend a little inside, but this tool can last up to 15 years.

4. Solar Panel Power Drone

Almost all drone products are embedded in a battery that allows it to fly for about 20 minutes. To overcome this, American companies develop drones that use wind and solar sell as their energy source. The advantage is, the energy source is endless and makes drone flight time relatively long. The main target of making this drone is industry that requires a drone to fly for a long time.

5. Solar Power Generation System

Solar power plants are also a development in Indonesia. With the use of the Solar Power Generation System, the monthly cost of electricity tokens can be reduced and saves on monthly budgets. In this modern age, the Solar Power Generation System can store large amounts of electrical energy during the day and be used at night or the next day.

Solar power is the process of converting sunlight into electricity, either directly using photovoltaic, or indirectly using concentrated solar power, CSP. The CSP system uses a lens or mirror and a tracking system to focus exposure to extensive sunlight into a small beam of light. PV converts light into electricity using the photoelectric effect.

Commercial CSP plants were first developed in the 1980s. Since 1985, installation of a 354 MW capacity CSP SEGS in the Mojave desert, California is the largest solar power plant in the world. Other CSP power plants include the Solnova solar power plant with a capacity of 150 MW and Andasol solar power plant with a capacity of 100 MW; both are in Spain. The 250 MW Agua Caliente Solar Project in the United States and the 221 MW Charanka Solar Land in India are the largest photovoltaic plants in the world. Solar projects exceeding 1 GW are being worked on, but most photovoltaics are installed on roofs with small capacity sizes, ie less than 5 kW, which are connected to power lines using net meters and / or feed-in rates

That is a brief discussion about the work, history and development of solar panel technology. It turns out that solar panels have many benefits, especially as an alternative tool to overcome the energy crisis in the future.

Reference:

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Kamis, 14 Februari 2019

Solar Panel Technology: How it works, History and Development

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