How Does Solar Energy Work?

Solar energy is the technology used to harness the sun’s energy and make it useable. Solar energy technologies include solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants and artificial photosynthesis.

The Sun is an incredibly large source of energy. To put it in perspective, consider this… 18 days’ worth of sunshine has an equivalent amount of energy as what is contained in practically all the natural resources (including natural gas, coal, oil etc.) on Earth.

As of now, there are two methods by which we harness the power of the Sun, i.e. solar energy: Photovoltaic technology and thermal technology. Let’s look at how each of these work.


Recommended Video for you:

If you wish to buy/license this video, please write to us at admin@scienceabc.com.

Photovoltaic technology

rooftop solar panels

Rooftop solar panels (Image Source: Wikipedia)

You have likely seen flat, glass-like structures installed in an angled fashion over rooftops of buildings and solar power plants. These are called solar panels, and they are solely responsible for taking light from sun-rays and running our electric appliances with that energy. The question is… how do they go about doing that?

Photovoltaic (PV) cells

Solar panels consist of the aptly named ‘photovoltaic cells’, which convert sunlight (photo) to electricity (volt). An array of photovoltaic cells make up a solar panel. These cells consist of silicon atoms that lose an electron when sunlight strikes their surface.

silicon atom

A silicon atom with 4 electrons in the outermost shell (Image Source: Wikipedia)

It works this way: sunlight consists of extremely small particles called ‘photons’ that are capable of knocking electrons off of the silicon atoms present on photovoltaic cells. These electrons make up direct current (DC), but as most of our household appliances function on alternating current (AC), it becomes important to convert electric current from DC to AC. This is done by another component called an ‘inverter’, which is yet another important element of the system.

Inverter

The inverter takes the DC formed by the excited electrons and converts it into AC, which is then routed to the main power supply of your house.

how does solar energy work diagram

This is how solar energy works

From there, that AC reaches different appliances through wires (note that the presence of the inverter in a solar energy system depends entirely on the type of current required by the system). As a result, the moment you flip the switch on, the electric circuit is completed and the bulb lights up!

Battery

Since you can only harness solar energy when there’s sunlight (e.g., when it’s not cloudy or rainy), batteries also form a noteworthy part of the system. Power generated throughout the day is stored in the battery to be used when required.

The efficiency range of the PV system typically lies around 20-22%, which means that it converts 20-22% of the sunlight falling on it into electric current. However, in the more common systems found on rooftops, the efficiency is a bit less.

Thermal technology

The other method of harnessing the energy from sunlight is through the use of solar thermal technology. This consists of ‘solar collectors’ – devices that capture solar radiation. ‘Flat plate’ and ‘evacuated tube’ are two types of collectors.

solar thermal collectors

Types of collectors: Flat plate collectors (left) and evacuated tube collectors

The flat plate variant, as its name indicates, consists of a dark flat plate absorber, containing a heat-transport liquid. Evacuated tube collectors, on the other hand, contain multiple evacuated glass tubes containing an absorber plate, along with a transfer fluid (e.g., water).

How does the thermal technology work?

Both of these thermal variants have different components, but the basic functionality remains pretty much the same in both.

solar thermal water heater

The basic working of a solar thermal water heater

In the presence of sunlight, solar collectors heat up and transfer the heat to the heat-transport liquid (typically water, or a mixture of glycol and water in cold regions to prevent the mixture from freezing). This liquid is then transported to a heat-exchanger liquid housed inside the water tank. After transferring its heat to the water in the tank, the heat-transport liquid flows back to the collectors to be heated again. This process is repeated until the desired temperature is achieved.

Note that no electricity is produced in this thermal energy case; instead, heat from the Sun’s rays falling on the system is transferred to another medium, such as water, food, etc.

a solar cooker

A solar cooker (Image Source: Wikipedia)

Therefore, water heaters and solar cookers are some of the most popular examples of systems that utilize solar energy to boil water and cook food, respectively. Solar thermal collectors typically have an efficiency in the range of 60-80%, which is much higher than the efficiency of a PV system.

Solar energy is undeniably a tremendous source of energy that can power houses and offices for extended periods of time. There are some countries that readily promote the use of solar and other renewable energy sources in order to ease the pressure on the limited natural resources on planet Earth and promote good conservation practices. With continuous improvements to the technology of harnessing solar energy, we’re getting closer to a world that is powered and heated purely by the power of the Sun… even at night!

Suggested Reading

Was this article helpful?
YesNo
Help us make this article better
Scientific discovery can be unexpected and full of chance surprises. Take your own here and learn something new and perhaps surprising!

Follow ScienceABC on Social Media:

About the Author

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spearheads the content and editorial wing of ScienceABC and manages its official Youtube channel. He’s a Harry Potter fan and tries, in vain, to use spells and charms (Accio! [insert object name]) in real life to get things done. He totally gets why JRR Tolkien would create, from scratch, a language spoken by elves, and tries to bring the same passion in everything he does. A big admirer of Richard Feynman and Nikola Tesla, he obsesses over how thoroughly science dictates every aspect of life… in this universe, at least.

.
Science ABC YouTube Videos

  1. Neutron Stars Explained in Simple Words for LaymenNeutron Stars Explained in Simple Words for Laymen
  2. How Robert J. Oppenheimer became the ‘Father of the Atomic Bomb’How Robert J. Oppenheimer became the ‘Father of the Atomic Bomb’
  3. Higgs Boson (The God Particle) and Higgs Field Explained in Simple WordsHiggs Boson (The God Particle) and Higgs Field Explained in Simple Words
  4. Slowing or Reversing Aging: Can We Live for 180 years?Slowing or Reversing Aging: Can We Live for 180 years?
  5. Detectives Use this Simple Technique to Find Your Fingerprints (Even AFTER You Have Wiped Them Off)!Detectives Use this Simple Technique to Find Your Fingerprints (Even AFTER You Have Wiped Them Off)!
  6. Why is a Circle 360 Degrees, Why Not a Simpler Number, like 100?Why is a Circle 360 Degrees, Why Not a Simpler Number, like 100?
  7. Quantum Mechanics Explained in Ridiculously Simple WordsQuantum Mechanics Explained in Ridiculously Simple Words
  8. Do Fish Get Thirsty and Do They Need to Drink Water?Do Fish Get Thirsty and Do They Need to Drink Water?