Photovoltaic Cells

483756270_2f2f1c3d3c_zPhotovoltaic cells are one of the most important ways to produce energy from the sun. A photovoltaic cell or solar cell can produce electricity for watches and small electrical appliances or for hundreds of houses when used at a more massive scale. It is a non – mechanical device that is made usually from silicon and is specially manufactured to absorb as much energy from the sun as possible. But how exactly do photovoltaic cells work?

How do photovoltaic cells work?

Solar energy is made of solar particles which are called photons. These photons contain various amounts of energy according to the wavelength of solar radiation that they belong to. When photons strike through a photovoltaic cell, the photons will either be reflected, pass through the cell or be absorbed. Only the photons that are absorbed by the photovoltaic cell can produce electricity.

When a great amount of photons hits the surface of the photovoltaic panel the electrons are removed from the atoms and this creates an electrical charge. Special care during the manufacturing of the photovoltaic cells makes it easier for electrons of the material to be released and in this way it becomes easier for electricity to be produced.

When the electrons move from one part of the photovoltaic cell to the other an electrical void is created. This causes more electrons to travel towards the same direction. When many electrons travel towards the same direction they create an imbalance of charge between the two parts of the conductor. In this way a voltage potential is created that is similar to the one between the two poles of a battery. When the two surfaces get connected with an external appliance electrical power is produced.

Solar arrays

The photovoltaic cell is the basic unit of the photovoltaic installation. Individual cells produce only one to two watts which of course is not enough for most electrical appliances. This is why photovoltaic cells are combined into modules and modules are combined together into arrays. Solar arrays are installed in many acres of land and are used to produce electricity in vast scales.

Efficiency

The efficiency of solar panels depends on the weather conditions. Fog and cloudy weather can greatly reduce the amount of sunlight received by a photovoltaic panel and in this way interfere with its performance. The efficiency of most photovoltaic modules ranges from 5% to 15% but researchers are trying to increase this percentage to 30%. As technology advances, increasingly efficient photovoltaic cells can be created that will absorb more solar energy even in adverse weather conditions.

Photo by flickr.com / Bernd Sleker

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What kinds of solar energy technology exist?

Solar panelThe amount of solar energy that reaches the surface of the earth in one day is more than the average energy that the world uses in one year. That is definitely a shocking statistic and it makes us wonder why we don’t use the sun more in order to produce the energy we need. One major reason may be that we have learned to rely too much on conventional ways of producing energy. Other reasons may include huge economic interests that guide the course of the global economy and the possible cost to transform the traditional ways of producing energy to more sustainable ones.

However, the progress of technology indicates that we could completely quit fossil fuel in the not so distant future. The more advanced the technology is the more effectively we can capture solar energy and leave behind us traditional forms of energy production. The type of solar installations and the technology used determine the effectiveness of solar capture and conversion. Currently there are three main technologies of solar energy:

Solar Thermal Collectors

Solar thermal collectors absorb directly the sun’s heat to warm up water or air. The warm water is used for domestic purposes or swimming pools whereas the warm air is used to heat up the inside of buildings. Solar thermal collectors are usually used for domestic purposes at a much smaller scale than solar thermal power plants.

Solar Thermal Power Plants

Solar thermal power plants work in a similar way to solar thermal collectors but concentrate more solar energy. Solar thermal power plants use mirrors to collect solar energy into a receiver. The receiver gathers the solar energy and then turns it into heat. This heat is then used to warm up a fluid that produces steam and generates electricity through a turbine.

Photovoltaic systems

Photovoltaic systems are one of the most popular ways of solar technology. They convert sunlight directly to electricity through a procedure that is called the PV effect. When the sun hits the solar panel it causes the electrons to move. In this way an electric charge is created. This electricity can be used to power houses, buildings and whole communities. Experts say that covering 4% of the world’s deserts with photovoltaic panels could cover our total need for electricity.

Photo by flickr.com / Chandra Marsono

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Advantages and Disadvantages of Solar Energy

3268270728_42b062c007_mDuring the last few decades solar energy has become a promising field in energy production that can cover our needs in electricity while ensuring environmental sustainability. Taking into consideration that the Earth receives at least 174 petawats of solar radiation per year, solar energy can be an excellent way to produce the electricity we need while we reduce greenhouse emissions.

One of the main benefits of solar energy is that it does not pollute the environment. As mentioned above, solar energy does not produce greenhouse emissions that could add to the greenhouse effect. In this time of increasing climate change with unpredictable consequences to civilizations and communities around the globe, using solar energy can be an effective way to ensure ecological sustainability without compromising the comfort of our daily lives. Careful planning of the photovoltaic installations can further improve their efficiency and bring more environmental benefits.

Furthermore, photovoltaic panels in houses can be a great way to produce energy for domestic purposes at a low cost. By installing photovoltaic panels on roofs of buildings lots of energy is saved because the distance between the production and the consumption unit is minimized. This can be translated into less money spent on electric bills. At the same time, this can make each house able to produce, store and use the amount of energy they want at the time they want to. As technology progresses and photovoltaic panels are produced at a more massive scale, more and more houses and businesses will afford to use solar energy for heating, cooling and electricity production.

In spite of the many advantages, solar energy has some disadvantages as well. One of its main limitations is that it is a source of energy that is not constant because it depends on the location, time of day, time of year and the weather conditions. Fluctuations in the amount of sunlight reaching the earth can have an impact on the amount of energy produced. This is why a lot of thermal / solar power plants use complementary sources of energy (such as gas or fossil fuel) or batteries when needed.

Last but not least, photovoltaic panels usually take up vast areas of land in order to produce energy at an effective rate because not so much solar energy can be concentrated on one single space at one single time. This can have a negative impact on the environment and can make it difficult to find suitable areas to install the photovoltaic panels. Careful selection of the locations and consideration of the multiple environmental factors can be a good way to mitigate the possible adverse environmental effects of solar energy installations.

In spite of the few disadvantages, solar energy is a solution that can help cover our energy needs and achieve environmental balance. All that it takes is to give a chance to this form of energy to prove its potential and leave behind practices that have damaged our planet to an unprecedented degree.

Photo by flickr.com / Sweet Tea

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Introduction to Solar Energy

imagesThe sun has been used as a source of energy for thousands of years. Since the ancient times civilizations like the Mayas, the Aztecs, the Greeks and the Romans used solar power to heat their homes and cook food. The sun was regarded in many of these ancient civilizations as a God who was worshiped in religious ceremonies. Only during the modern times however the human civilization has developed the technology to capture solar energy and produce from it electricity for homes and industries.

Solar energy is essentially the radiation of the sun that reaches the Earth. In one whole year the Earth receives almost 174 petawats (PW) of incoming solar radiation. From this energy a 30% is reflected back to space and the rest is being absorbed by oceans, clouds and land. The solar light that reaches the earth ranges from the visible to the infrared part of the spectrum and equals to 3.850.000 exajoules per year.

At solar thermal power plants solar energy is captured and turned first into heat and then electricity. At these plants the heat from the sun is used to warm up water and produce steam. This steam is used to generate a turbine that produces mechanical energy. This mechanical energy is turned afterwards into electricity with the use of a turbine in order to warm up water for homes, heat up greenhouses and for other industrial purposes.

Solar energy can be turned directly into electricity through the use of Photovoltaic cells (PV). A photovoltaic cell is a non-mechanical device that is usually made of silicon. When the photons from the sun hit the surface of the photovoltaic cell they cause a certain amount of electrons to be removed. This creates an electrical charge that when connected to an external generator can produce electricity. Individual PV cells are combined into panels to produce electricity in larger scales.

Through this kind of technologies an enormous amount of solar power can be captured and used for electricity production. Given the fact that solar energy does not pollute the atmosphere solar thermal power plants and photovoltaic cells can be a great way to cover our energy needs without further destroying nature.

Photo by en.wikipedia.org / NASA’s Solar Dynamic Observatory

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