Solar power is an energy source based on the solar cell technology, which converts energy obtained from the Sun into electricity. Solar panels are arrays of solar cells which generate a sizable amount of electric power.
Considering that our Earth receives roughly 1000 watts of solar energy per square meter, the solar cell technology promises to be the energy source of the future. However, the cost of solar cell production and their low efficiency are proving to be barriers, in making the technology available to the common man. Still there is a promise that research advances in the future, will make solar cells cheaper and accessible to common people in developing countries.
How Do Solar Panels Work and Generate Electricity?
As I said before, solar panels are arrays of individual solar cells connected in series to generate electricity. One has to first understand how the solar cell or solar photovoltaic cell works.
The name photo - voltaic itself means that the cell converts energy obtained from photons into electricity (volt). There was a time when solar cells were used only in space applications to power satellites and space crafts! With technical innovations and private enterprises entering the field, the production of solar cells has become possible. They are now used to power everything from calculators, cars to space crafts.
Working of a Solar Photovoltaic Cell
Photovoltaic cells are made up of special types of materials called 'Semiconductors'. The most widely used semiconductors are silicon and germanium. They are insulators in the natural state. However, they can be converted into conducting materials, by adding small quantities of doped elements. Such doped semiconductors are used in constructing photovoltaic cells.
Let us see what happens when such a solar cell is connected in a closed electric circuit and kept in the sun. This explanation is simplistic and a bit naive but conveys the essence of the principle which operates the solar cell. There are technical details which I am not venturing into, since this is intended for a layman audience. This will convey the gist of how solar panel works.
When photons fall on the surface of solar cells, electrons in the semiconductor are knocked out or freed by the absorption of energy. Every such photon is like a missile dislodging electrons from its orbits around the atom. Every ray of sunlight contains millions of such photons which strike the semiconductor surface of a photovoltaic cell.
Every photon helps in liberating electrons from their atomic shells. This creates a bunch of free electrons in the semiconductor which can be made to flow if an electric field is applied across the solar cell. This gives rise to a minuscule current across the semiconductor, which can be drawn for external use, through the use of metal contacts placed on the surface.
This current is very weak and not powerful enough. The efficiency of solar cells of the best manufacturing quality is less than 30%. That means 70% of the solar energy which falls on these solar cells goes unused. However, its electricity generated by solar energy, which in itself is a huge breakthrough.
To convert this small electric output, into a sizable one, arrays of hundreds and thousands of solar cells are bunched together to create solar panels. The electricity generated by each photovoltaic cell is combined through a series connection of such cells in the panel. The combined electric voltage output of the solar panel is given to a rechargeable battery where it is stored for further use!
The best thing about solar cells is that they generate electricity without pollution, unlike other sources of electricity generation. Solar power is increasingly being used in the developed world, but it's still far away from making inroads into the power hegemony of oil giants.
Solar energy is the path to a green tomorrow! If the production technology of solar cells is made cheaper, it can be mass produced and distributed in huge numbers, which will reduce dependence on conventional sources of energy, which are fast depleting!