Skip to content

How Do Solar Cells Work Essay

Solar Energy

We all have been using sun’s energy since years for numerous purposes but only recently we have started using the sun’s energy for generating power. About 70% of the light that hit the earth gets reflected back to space and only the remaining 30% light is enough to meet up our needs for years to come. So, solar energy is the energy that we get from the sun. We get enough energy from the sun that it could meet up our power demands, if only we could harness it properly. The energy that is absorbed by the earth is used for drying clothes, used by plants in the process of photosynthesis, taken in by the ocean where the heat creates wind and heat currents and for heating up homes.

How Solar Energy Works?

When we get the solar energy from the sun it gets trapped and stored and can be used in various ways to generate power. Solar energy can be used as direct or indirect, active or passive. Basically there are 2 ways in which we can harness sun’s energy:

1. Solar Thermal: Solar thermal is also known as solar water heating. In this process, solar energy is used directly to generate heat. Solar panels are used to trap the heat from the sun and are used to heat water in the glass panels. Glass panels are painted black so that they absorb maximum energy from the sun, then water is pumped through these pipes. These panels are positioned in such a way to maximize the absorption of heat throughout the day and can help in reducing the electricity bills.

2. Photoelectric Cells: This method converts the sun’s energy into electricity. Photovoltaic cells are most popular form of converting solar energy into electricity. These cells are silicon based pieces of materials that absorb the sun’s light. When the sunlight enters the cells, it causes the electrons to move. These electrons move in a certain direction which is known as current. This electricity is in the form of direct current.The electrical output from a single cell is small, therefore individual solar cells are arranged together in a PV module and the modules are grouped together to form an array. This power is then used to charge cells or inverters and this electricity can be used to provide sufficient power for common electrical appliances.

Solar energy is available throughout the world and in many parts of the world it is possible to capture that energy and use it to meet up our growing demands. The main benefit of solar energy is that it doesn’t cause any or little pollution, is a free energy source and is available in abundant quantity. If utilized to it’s full potential it can help us in overcome our dependence on fossil fuels and also can help us greatly in reducing the global warming.

References:

http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-solar-energy-works.html

http://www.scientificamerican.com/article.cfm?id=how-does-solar-power-work

http://www.treehugger.com/clean-technology/how-does-solar-energy-work.html

Rinkesh

Rinkesh is passionate about clean and green energy. He is running this site since 2009 and writes on various environmental and renewable energy related topics. He lives a green lifestyle and is often looking for ways to improve the environment around him.

Latest posts by Rinkesh (see all)

Rinkesh

Clean Power

Published on September 30th, 2011 | by Glenn Meyers

How Do Solar Panels, Solar Cells and Solar Energy Work?

September 30th, 2011 by Glenn Meyers 


US Army personnel with solar paels in Africa

With all the news about solar power lately, I thought it would be useful to go back to how PV solar panels work.

(For a comprehensive look at some other solar power technologies, check out this piece: Hot Panels, Practical but Not Yet Popular – A Solar Overview.)

The short description goes something like this: Silicon is mounted beneath non-reflective glass to produce photovoltaic (PV) panels that collect photons from the sun and convert them into DC electrical power. That DC power then flows into an inverter, which transforms it into basic AC (alternating current) electrical power.

Okay, that’s the short and simple answer, but others may want more information. A useful website, Solar Home, offers an in-depth answer to the question, especially about one of the key materials, silicon.

Solar Home writes: “Silicon has four electrons in its outer shell. However, it has the capacity to hold eight. By sharing these four electrons with other silicon atoms and their four shell electrons, the capacity of eight is filled. When they combine with each other in this way, silicon atoms develop a strong, stable bond. This structure is known as pure, crystalline silicon.”

Pure silicon, however, is not a good conductor of electricity because there aren’t any electrons that are free to move. In other words, adds the author, “The silicon is better off with impurities.”

Thus, silicon is combined with an element such as phosphorus, which has five electrons to share. As a result, a negative charge is created. Silicon can only take four of the five electrons, leaving one free electron – called a free carrier – to carry an electrical current.

Other methods for manipulating silicon are also used. For instance, when silicon is combined with an element containing three electrons, a positive charge can be created. Boron is one material that suits this purpose. When silicon and boron are combined, holes are created.

“These silicon combinations and their differing charges are used to make solar panels. As photons come down from the sunlight and strike the silicon, it shakes everything up. The free electron that was hanging onto the silicon/phosphorous combination is now forced to the outer ring. From here, it gets sucked up to the outer ring of the silicon/boron combination. This is how electricity is created.”

NASA Science also provides solid information on the subject, writing that the photoelectric effect was first noted by a French physicist, Edmund Becquerel, in 1839. He learned that certain materials would produce small amounts of electric current when exposed to light. Here we learn that, in 1905, Albert Einstein described the nature of light and the photoelectric effect on which photovoltaic technology is based. For this discovery, he eventually won a Nobel Prize in physics.

Source: NASA

This NASA diagram illustrates the operation of a basic photovoltaic cell, also called a solar cell, the building block of solar panels. Solar cells are made of the same kinds of semiconductor materials, such as silicon, used in the microelectronics industry. For solar cells, a thin semiconductor wafer is specially treated to form an electric field, positive on one side and negative on the other. When light energy strikes the solar cell, electrons are knocked loose from the atoms in the semiconductor material. If electrical conductors are attached to the positive and negative sides, forming an electrical circuit, the electrons can be captured in the form of an electric current — that is, electricity. This electricity can then be used to power a load, such as a light or a tool.

This information from Scientific Americanprovides solid information on solar energy basics  for those wanting to know more about how solar power works in the first place: “The sun’s light (and all light) contains energy. Usually, when light hits an object the energy turns into heat, like the warmth you feel while sitting in the sun. But when light hits certain materials the energy turns into an electrical current instead, which we can then harness for power.”

Hope this information about how solar panels work is helpful.

Image Credits:  US Army Africa & NASA


Tags:How do solar cells work, NASA, silicon in solar panel, solar home, Solar PV, the basics in solar energy, understanding solar panels


About the Author

Glenn Meyers is a writer, producer, and director. Meyers was editor and site director of Green Building Elements, a contributing writer for CleanTechnica, and is founder of Green Streets MediaTrain, a communications connection and eLearning hub. As an independent producer, he's been involved in the development, production and distribution of television and distance learning programs for both the education industry and corporate sector. He also is an avid gardener and loves sustainable innovation.