Could solar energy replace fossil fuels and save the planet?

Fossil fuels are actively destroying our planet. In fact, according to the European Environment Agency (2021), about two thirds of greenhouse gas emissions worldwide can be sourced back to the burning of fossil fuels. As we continuously seek to replace these non-renewable energy sources by green alternatives, solar energy comes in. Solar energy is a renewable energy source, which is simply defined as “any energy generated by the sun” (National Geographic Society, n.d.). One of the most popular ways that it is harnessed is through solar panels. The image below (Fig. 1) shows the CO2 emissions of solar and wind energy (renewable energy sources) compared to coal and natural gas (non-renewable energy sources). From this, we can see how significantly solar energy can reduce CO2 emissions and protect our climate.

Fig. 1: A comparison of the CO2 emissions from different energy sources (1)

You may be wondering: if solar energy is so great, why haven’t more fossil fuel power stations been replaced by solar farms? Well, solar panels aren’t exactly the most efficient energy producers. Solar panels tend to have an efficiency of around 15-20%, while coal can have an efficiency of up to 40%, and natural gas of up to 60% (Parkman, 2022). This makes it challenging to replace non-renewable energy sources by solar panels, as much more space and resources are needed to produce the same amount of energy. Now, is there any way we can solve this problem? Could we make solar energy more efficient?

In 2014, four researchers from different scientific institutes in Islamabad did an experiment in which they explored how mirroring and cooling systems affect the efficiency of solar panels. Mirroring is a process in which on top of the sun reaching a solar panel directly, a mirror is placed so that light reflects from this mirror to the solar panel. This allows more sunlight to reach the solar panel at once. (See Fig. 2.) Cooling systems simply help to keep the solar panel cool.

Fig. 2: Mirroring system on a solar panel (2)

To understand why mirroring and cooling systems could make solar panels more efficient, let’s take a look at how a solar panel works. Solar panels are made of smaller components, called solar cells. These cells are made of two layers of semiconducting materials that are contaminated with different impurities. This produces an unequal distribution of free electrons between the layers; the n-type (negative-type) layer contains free electrons, while the p-type (positive-type) layer contains “holes”, which are basically empty spaces for electrons. As photons from the sun reach the solar cell, the loosely bound electrons in the n-type layer enter an excited state and escape their respective atoms. With help of an external circuit, the electrons are then able to flow toward the p-type layer, where atoms are hungry for electrons. The flow of electrons in the external circuit produces electricity. (Arshad et al, 2014). See Fig. 3.

Fig. 3: A simplified depiction of how a solar panel works (3)

Now, to explain how mirroring can increase efficiency, we highlight the idea that photons from the sun reaching the solar panel release electrons from their respective atoms. As more photons reach the solar panel, more electrons will be free-bounded, and therefore more electric current can flow. Therefore, as photons are reflected from a mirror to the solar panel, more photons reach the solar panel and so more energy is produced. 

This however introduces us to a new issue: resistance. Resistance blocks the flow of a current, lowering the amount of energy production. As photons reach the solar panel, this energy is absorbed by electrons, which then speed up and collide with one another, increasing the temperature of the panel. An increase in temperature causes an increase in resistance, hindering the flow of the current. In fact, the efficiency of a solar panel is estimated to decrease by 0.5% for every degree that its temperature rises. (Arshad et al, 2014). This is where cooling systems come to play: cooling systems can help to keep the solar panel at a good operating temperature, which minimizes the effects of resistance on energy production.

As we have now developed a brief understanding of solar panels, as well as mirroring and cooling systems, let’s revisit the experiment. Researchers conducted an experiment in which they measured power outputs of solar cells without any mirroring or cooling systems, with only mirroring and no cooling systems, and with both mirroring and cooling systems. After collecting this data, they created graphs comparing the irradiance, power and efficiency seen over time of these different conditions. By analyzing these graphs, the researchers were able to recognize that the best results are seen when both mirroring and cooling systems are installed to a solar panel.

The findings of the experiment show that mirroring and cooling systems significantly increase the power outputs of a solar cell. Mirroring alone already provides a clear improvement in the efficiency of a solar panel: a 32% increase is seen in the power outputs. With the help of cooling systems, this efficiency is increased by another 20%. Hence, if both mirroring and cooling systems are used on solar panels, their efficiency can be increased by a whopping 52%! 

One thing that the researchers realized however, was that during early and late hours of the day, the cooling system actually decreased the efficiency of the solar panel, as it prevented enough energy from reaching the electrons to release them from their respective atoms in order to create a flow of current. Therefore, a way that solar panels could be made even more efficient is by deactivating cooling systems during these hours to make sure the energy production is not hindered. 

The results of this experiment gives us hope for a green future. By using various mechanisms, such as mirroring and cooling systems, we can increase the efficiency of solar energy by large amounts, making it a realistic alternative to non-renewable energy sources. So, to answer the very question of this blog post: yes, solar energy can replace fossil fuels and effectively save our planet. We just need to continue its research so we can make it a reliable energy source for our future. Let’s go solar!

Fig. 4: Let’s go solar! (4)

 

The study:

R. Arshad, S. Tariq, M. U. Niaz and M. Jamil, “Improvement in solar panel efficiency using solar concentration by simple mirrors and by cooling,” 2014 International Conference on Robotics and Emerging Allied Technologies in Engineering (iCREATE), 2014, pp. 292-295, doi: 10.1109/iCREATE.2014.6828382.

Bibliography:

Energy and climate change. (n.d.). European Environment Agency. 

https://www.eea.europa.eu/signals/signals-2017/articles/energy-and-climate-change

Solar Energy | National Geographic Society. (n.d.). 

https://education.nationalgeographic.org/resource/solar-energy/

Parkman, K. (2022, May 12). Solar energy vs. fossil fuels. ConsumerAffairs. 

https://www.consumeraffairs.com/solar-energy/solar-vs-fossil-fuels.html

Image sources: 

1. Herr, C. (2022, July 3). Are Solar Panels Better than Coal? Climate Solution Center. https://climatesolutioncenter.com/are-solar-panels-better-than-coal/
2. How to boost any solar panel output by 75%. (n.d.). https://geo-dome.co.uk/article.asp?uname=solar_mirror
3. How Solar Panels Work? (n.d.). NT Energy Solutions. http://www.nt-energysolutions.com/en/Article/Detail/101877
4. SolarResource.org. (2019, October 10). Best Solar Energy Memes From Around The Web. Solar Resource. https://solarresource.org/best-solar-energy-memes-around-webz/