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construction of solar cell booster-image 1
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Inspiration
Climate change is significantly affecting all forms of life on this planet. A major contributor to climate change is the gas CO2. Carbon dioxide absorbs energy at a variety of wavelengths and is responsible for global warming. A major source of CO2 in the atmosphere is the combustion of fossil fuels to generate electricity. Replacing the use of fossil fuels with renewable sources of energy, for example solar, will significantly reduce CO2 emissions. However, the unreliability of solar energy and its lower efficiency is the reason why most people don't use solar energy as the primary source of generating electricity. This project aims to improve the efficiency of solar panels in an attempt to popularize renewable sources of energy, in order to reduce the adverse effects of global warming.
What it does
The efficiency of solar cell is defined as the amount of solar irradiance incident on the cell which is converted to electricity. This efficiency is typically quite low, due to which solar cells are less preferred over fossil fuels. This project aims to improve the efficiency of solar cells by ensuring maximum absorption of incident light (by minimizing reflection losses) and preventing overheating of solar cells, which can adversely affect the efficiency. This project uses CdTe single junction solar cell, since the bandgap of this material is optimum to produce high efficiency. The shape of the cell is dome shaped. This is done because, regardless of the angle of incidence, the light will always be incident along the radius, thus allowing maximum absorption. In order to facilitate maximum absorption of solar energy, the outer surface is coated with a thick black layer. This is capable of absorbing more wavelengths of the electromagnetic spectrum. The inner layer is coated with aluminum in order to reflect any light back to the solar cell, which might have escaped absorption by the cell. The layer just within the aluminum layer is made of vacuum to minimize convection losses. The next layer is composed of air at 25 degrees Celsius, just outside the PV cell. This helps to keep the temperature of the cell at optimum values while ensuring maximum solar radiation to be incident on the PV panel. The bandgap of CdTe solar cell is optimum for maximum utilization of the incident solar energy. The remaining parts (heavily doped n-junction, lightly doped p-junction layer) are similar to a conventional single-junction solar cell. This mechanism thus helps in absorption and utilization of maximum solar radiation.
How we built it
I've used data from various websites and studied the key concepts from YouTube and Khan academy to gain insights of the current scenario and developments in the field of solar energy. I've studied some fundamental concepts of physics including blackbody radiations, Shockley-Queisser limit, working of pn junction diodes, single and multijunction solar cells etc.
Challenges we ran into
1) The Shockley-Queisser limit restricts the maximum solar efficiency of single junction solar cell to 33.7%. In addition to this being a very low efficiency, it can only be attained under ideal conditions, thus making even the maximum efficiency of solar cells way below that obtained from non-renewable energy sources. It is very challenging to mitigate the factors that cause the efficiency to be this low. 2) The efficiency of solar panels is a function of temperature. As the temperature rises above 25 degrees Celsius, the efficiency falls drastically. It is thus crucial to maintain optimum temperature at the solar cell regardless of external environmental temperature. 3) The design of the solar panels must be such that it absorbs maximum solar radiation depending on the position of the sun and angle of incidence of solar radiation (solar tracking systems that follow the sun are expensive and complex to design).
Accomplishments that we're proud of
This strategy for combating climate change (by increasing the use of renewable energy) has not been infringed from any source. The concepts related to renewable energy have been closely studied and the latest developments in this field have been taken into account.
What we learned
This project helped me to understand the ill-effects of fossil fuel combustion on the environment and one of the ways to reduce its disastrous effects, i.e. to switch to renewable sources of energy. While conducting research for this project, I came to know about various strategies and lifestyle changes that help save the environment, which I am sure to follow henceforth. This project helped me explore various concepts of physics, chemistry, math and biology. Overall, I found this project topic highly relevant in today's times.
What's next for Solar Efficiency Booster
At the given instant, this project is still in the ideation stage. The next part will be to construct these solar cell models and quantitatively measure the efficiency of these cells. This will help verify the credibility and effectiveness of this project.
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