Solar Panels And Photovoltaic devices

A photovoltaic (PV) cell, also called a solar cell, is an electrical component that creates electricity when photons, or light particles, are exposed to it. The photovoltaic effect, named after French physicist Edmond Becquerel, was first identified in 1839. Photovoltaic cells did not find their first practical application in satellite technology until the 1960s. 

Solar Power:

Solar power is an infinitely renewable energy source since the sun has been radiating an estimated 5000 trillion kWh of energy for billions of years and will continue to do so for another 4 billion years. Solar energy is a type of energy that is used in electric cookers, water heaters, and other appliances. The main disadvantage of solar energy is that it cannot be generated without sunlight. Solar cells, which transform solar energy into electrical energy, bypass this constraint. We will study about photovoltaic cells, their benefits, and drawbacks in this part.

Flow of Electricity:

The migration of electrons, each with a negative charge, toward the cell’s front surface causes an electrical charge imbalance between the front and back surfaces. This imbalance, like the negative and positive terminals of a battery, provides a voltage potential. The electrons are absorbed by the cell’s electrical conductors. Electricity flows in an electrical circuit when the conductors are connected to an external load, such as a battery.

Photons Carry Solar Energy:

Photons, or solar energy particles, make up sunlight. The varied wavelengths of the sun spectrum correspond to different amounts of energy in these photons.

A semiconductor substance is used to make a PV cell. Photons striking a PV cell may bounce off of it, pass through it, or be absorbed by the semiconductor material. Only the photons that have been absorbed supply enough energy to generate electricity. When enough sunshine (solar energy) is absorbed by the semiconductor material, electrons are dislodged from the substance’s atoms. During production, a special treatment of the material surface makes the front surface of the cell more sensitive to dislodged, or free, electrons, allowing them to naturally migrate to the cell’s surface.

How a Photovoltaic Cell Works:

When photons impact a semiconductor material such as silicon, the electrons in its atoms are released, leaving a free space. The wayward electrons roam around aimlessly in search of a new “hole” to fill.

However, in order to generate an electric current, the electrons must all move in the same direction. Two forms of silicon are used to do this. The sun-exposed silicon layer is doped with phosphorus atoms, which have one more electron than silicon, while the other side is doped with boron atoms, which have one less electron. The resulting sandwich functions similarly to a battery: the layer with excess electrons is designated as the negative terminal (n), while the side with a lack of electrons is designated as the positive terminal  (p). At the point where the two layers meet, an electric field is formed.

The electrons are swept to the n-side by an electric field when they are stimulated by photons, while the holes drift to the p-side. The electrons and holes are directed to the electrical contacts on both sides before passing as electrical energy to the external circuit. This results in a direct current. To reduce photon loss due to surface reflection, an anti-reflective coating is applied to the top of the cell.

Efficiency of  Photovoltaic Cell:

The efficiency of a cell is the ratio of the electrical power it produces to the amount of sunlight it receives. The cells are joined into modules, which are then assembled into arrays, to test efficiency.

Peak power, or the amount of electricity generated by the system, is a proportion of the solar energy received. The efficiency of a panel of one square metre that provides 200 W of electrical power is 20%. PV cells have a theoretical maximum efficiency of roughly 33%. The Shockley-Queisser limit is the name for this limit.

Applications:

Calculators and wristwatches are powered by the tiniest photovoltaic systems. Larger systems can generate electricity to pump water, power communications equipment, power a single home or company, or construct vast arrays that offer electricity to tens of thousands of people.

PV systems have the following advantages:

• PV systems can provide electricity in areas where there are no electricity distribution systems (power lines) and they can also provide electricity to a power grid.

• PV arrays may be readily installed and are available in a variety of sizes.

• PV systems mounted on buildings have very little environmental impact.

Disadvantages:

• Solar panels have a low efficiency when compared to other renewable energy sources.

• It can only be used in the presence of sunlight. 

• Solar energy transmission over long distances is inefficient and difficult. 

• Photovoltaic panels are delicate and can be easily damaged. 

Conclusion:

A solar cell, often known as a photovoltaic (PV) cell, is a non mechanical device that transforms sunlight directly into energy. Artificial light can be converted to power by some PV cells. A semiconductor substance is used to make a PV cell.