What is Solar Energy ?

Solar (in Latin, solar means sun) powered gadgets like solar cookers and dryers, solar water heaters, solar cell phone chargers, solar calculators and solar emergency lights etc. are very popular nowadays. Do you know there are gadgets such as solar air conditioners and solar chimneys too? In fact there are full solar power plants too. Solar energy is becoming more and more popular and with good reason too.

Let’s know more about solar energy.

Solar energy definition

To give a very simple definition, solar energy is energy harnessed from the sun’s radiation. Solar energy can be of two types:

• Passive solar energy- When we utilize sun’s energy in its natural form, it is passive solar energy. For example sun drying laundry or using daylight to read.
• Active solar energy- When we harness or convert solar energy into another form of energy such as heat or electricity, using solar cells/panels/ dish etc., it is called active solar energy. For example, using solar cell phone chargers to charge phones or installing solar water heaters to get hot water or installing solar powered streetlights are all examples of active solar energy.

Where does solar energy come from?

You already know that the sun is actually a star around which our earth orbits along with several other planets. You may also know that sun is actually a super hot ball of gases named hydrogen and helium that go off like nuclear bombs and emit heat and light that comes out of sun to radiate all around. To put it very simply, this heat and light emitted by the sun is solar energy. Sun is the source from where all solar energy comes.

Is solar energy renewable?

Yes. For all practical purposes, the sun is an infinite source of energy (it has a remaining lifespan of another 5 billion years!). Then harnessing sun’s energy produces no by-products bad for environment. So we can say that solar energy is indeed a renewable source of energy.

Advantages of solar energy

• Sun is a virtually free source of energy that will be available for use for billions of years, unlike petroleum or coal that will be depleted in a few decades’ time.
• Solar energy is environment friendly, non-polluting and emits no smoke or greenhouse gases. You don’t need to dig mines, or drill holes or cut forests to get its raw material. The sun supplies it plentiful from morning to evening everyday!
• Solar energy can be used in remote areas too without needing conventional electrical grid.
• Once installed, solar energy generators need no raw material except sunlight to get to work.

Disadvantages of solar energy

• Solar power stations are expensive to build and solar gadgets too are comparatively steep in price.
• Solar power plants are bulky and require large land areas to set up.
• You need sunshine or daytime for solar energy generation. Cloudy weather, rains and nights are not conducive to it. If you live in regions where daylight hours are limited, you may not get enough sun rays to use your solar gadget effectively. True, solar batteries charged in daytime can work at night but these are bulky, expensive and need lots of maintenance.
• Manufacturing of solar energy harnessing equipment causes some pollution.

History of solar energy

Actually speaking, all life on this earth has been using solar energy passively since time immemorial, for the simple reason that sun is the prime source of all energy for the entire earth. If it weren’t for solar energy, there would be no plants, no animals, and no human beings.

However in the modern context, harnessing of solar energy to convert it into other forms of energy was first thought of by a French scientist named Alexandre Edmond Becquerel who at the age of just 19, built the first photovoltaic panel in 1839. Another interesting tidbit, famous British astronomer Sir John Herschel used a primitive solar cooker to cook food when on an expedition in Africa in 1830s. Using lenses to focus sun’s rays on paper or kindling to start a fire is also an old, old trick.

Do you have a solar powered gadget at home or school? Have you ever personally used a solar powered gadget? Write in and tell us.