Yash
Perovskite solar cells technology is exhibiting higher efficiencies with the potential of increased performance in a near future.
Because our engineers and scientists are experimenting and making efforts to develop a new technology that could increase the performance of solar cells, boosting the feasibility of the Solar Power System.
What is Perovskite?
The real Perovskite is a Calcium Titanium Oxide mineral having a chemical formula of CaTiO₃.
These are anhedral crystals (crystals that have no well-defined edges) that generally grow from the cooling of liquid magma.
These crystals were first discovered in the Ural Mountains (Russia) by Mr. Gustov Rose in 1893 and this mineral was named after Russian mineralogist Mr. Lev Perovski.
- It has a cubic structure with a general formula of ABX₃.
- ‘A’ and ‘B’ are cations and ‘X’ is an anion
- ‘A’ cations are generally larger than the ‘B’ cations
Any class of compounds that has a similar structure to that of Perovskite (CaTiO₃) are termed as Perovskite structures.
Perovskite is a semi-conductor that conducts electricity when sunlight falls on its surface.
It requires very less area to capture the same amount of light when compared with other solar cell technologies.
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What are Perovskite solar cells?
Perovskite solar cells are like thin-film solar cells that are made from perovskite structured compounds.
Usually Methyl-ammonium lead halide: CH3-NH3-Pb-X where X is halogen ion like Iodide, Bromide, or Chloride).
Their crystal structure increases the sunlight conversion efficiency.
But the solar cell sunlight conversion is limited to 33.7% by the Shockley-Queisser limit.
According to it, the maximum theoretical efficiency of single-junction silicon solar cells is 33.7%.
And the ideal bandgap for this maximum power efficiency should be 1.34 eV.
And achieving this ideal energy band gap is quite difficult.
But with Perovskite solar cells, we can tune the energy bandgap close to the ideal energy band gap of 1.34 eV.
This is done by adjusting the halide content in the compound.
Resulting in higher efficiencies close to the Shockley-Quiesser limit.
Why Perovskite solar cells?
High Efficiency
One of the biggest advantages of Perovskite solar cells is their high efficiencies.
Scientists hope that their high absorption coefficient can beat the efficiencies of traditional mono- and poly-crystalline solar cells.
These cells have already achieved lab efficiencies of 20% and above.
Low Cost
Unlike traditional silicon mono- and poly-crystalline solar cells, the fabrication process of Perovskite solar cells is less expensive.
Whereas, for making silicon solar cells, the raw material is first extracted from the earth and then it is processed for making solar cells.
This process is time-consuming and expensive.
Attractive Features
The Perovskite solar cells do not put extra stress on the roof surface.
Because they are thin, flexible, transparent, and are lightweight.
Moreover, their flexibility and transparency add aesthetic value to your home.
Disadvantages of Perovskite solar cells
They produce iodine vapors when they come in contact with oxygen and moisture.
This degrades the Perovskite layer.
Also, more water is produced in the presence of atmospheric oxygen, creating a chain reaction.
This leads to further degradation of the Perovskite layer.
Solar scientists are finding new ways to reduce Iodine vapor formation to delay the degradation of Iodine-based solar cells.
Another big issue is the environmental impact due to lead-based Perovskites.
While converting sunlight into the current, the lead-based Perovskites produce Lead-Iodide as the by-product of the reaction.
This Lead-Iodide is toxic and is a health hazard when inhaled.
Researchers are trying new substitutes that can replace toxic materials with safer ones.
Feasibility of Perovskite solar cells
Cost/watt
In terms of cost/watt, the Perovskite solar cell is a clear winner.
These cells are very cost-effective because of their easy manufacturing and fabrication process.
That is done in the lab through a wet chemical process.
Whereas, for making high-efficiency silicon solar cells, the silicon crystals are first extracted from the surface of the earth.
Durability
The Perovskites fall short in terms of durability when compared with silicon solar cells.
The longest duration that they can withstand real climatic conditions is 1 year.
Whereas silicon solar cells can withstand it for 25 years.
Efficiencies of Perovskites
The efficiencies of both types are quite comparable.
Perovskites-based solar cells have achieved near to 20% whereas mono-crystalline silicon cells have crossed 25%.
Annual return by Perovskites solar cells based solar panels
Yash, can you quantify the annual return if Perovskites solar cells are used to generate electricity for our homes?
Okay!
Let me figure out the formula for this:
Relation between Efficiency and Durability
Efficiency and Durability is directly proportional to the annual return offered by the system
whereas the cost of the system is inversely proportional to the return offered.
Consolidating the above relations in one equation:
This indirect formula helps in finding the annual return offered by the Perovskite solar power system.
We know that a mono-crystalline solar panel-based power system offers an annual average return of 15%.
(*The absolute return varies depending on various factors like sunlight, grid rate, maintenance cost, cost of the system, cost of capital, and many more).
Doing little MATH
Let us find the annual return offered by the Perovskite-based solar power system based on the above 3 factors:
You can see that the average return offered by Perovskite (based on the above 3 parameters, namely Efficiency, Durability, and Cost/watt) is 2.4%.
The main issue with the Perovskites is their stability.
If scientists can somehow achieve the stability of 6.25 years of Perovskite-based solar cells by suppressing the formation of Iodine vapors.
And can make them more water-resistant then we can match their annual return with that of the mono-crystalline-based solar power system.
Another challenge is finding those perovskite structures whose by-products do not impact the environment.
Their increase in efficiency in a short period has attracted the attention of scientists around the world.
In the future, we can see Perovskite-based solar power systems installed on the rooftops of the homeowners.
