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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