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 Solar Power System.
Perovskite solar cell technology is exhibiting higher efficiencies with the potential of increased performance in a near future.
This is our topic of discussion in today's post.
What is Perovskite?
The real Perovskite is a Calcium Titanium Oxide mineral having a chemical formula of CaTiO₃.
These are anhedral crystals (crystals which have no well-defined edges) that generally grow from the cooling of liquid magma.
These crystal were first discovered in Ural Mountains (Russia) by Mr. Gustov Rose in 1893 and this mineral was named after Russian mineralogist Mr. Lev Perovski.
Perovskite is a semi-conductor which 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.
Perovskite Solar Cells
Perovskite solar cells are like thin-film solar cells that are made from perovskite structured compound (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 and these types of solar cells are called Perovskite solar cells.
The solar cell sunlight conversion is limited to 33.7% by the Shockley-Queisser limit.
It states that the maximum theoretical efficiency of single-junction silicon solar cell can be reached to 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 band gap close to the ideal energy band gap of 1.34 eV 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 that can be prepared in the lab.
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 are thin, flexible, transparent, and are lightweight. It means they can be directly embedded on the roof without adding extra stress to its surface.
Moreover, their flexibility and transparency add aesthetic value to your home.
The main challenge for solar scientists and engineers is to improve the stability of Perovskite Solar Cells.
These cells degrade more quickly in moisture, UV radiations, and elevated temperatures.
It is found that when Iodine based Perovskite solar cells come in contact with moisture and atmospheric oxygen during their operation, the Iodine vapors are produced which degrades the Perovskite layer.
In the presence of atmospheric oxygen, more water is produced that creates a chain reaction, leading 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 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.
I'm taking the parameters of mono-crystalline silicon cells for comparison to evaluate the feasibility of the Perovskite solar cell.
In terms of cost/watt, the Perovskite solar cell is a clear winner. The manufacturing and fabrication of these cells are very cost effective that can be done in the lab through a wet chemical process.
the silicon crystals are first extracted from the surface of the earth and then these are processed for making the high-efficiency solar cells.
The Perovskites falls short in terms of durability when compared with silicon solar cells.
The longest duration that they can withstand the real climatic conditions is 1 year whereas silicon solar cells can withstand it for 25 years.
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%.
Yash, can you quantify the annual return if Perovskites solar cells are used to generate electricity for our homes?
Let me figure out the formula for this:
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 formula will help us in finding the annual return offered by the Perovskite solar power system through an indirect method.
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)
Let us find the annual return offered by Perovskite based solar power system based on the above 3 factors:
You can see that the average return offered by Perovskite (based on 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 it more water-resistant then we can match their annual return with that of mono-crystalline based solar power system.
Another challenge is finding those perovskite structures whose by-products while producing electricity, do not impact the environment.
The improvement in the efficiency of Perovskite solar cells in a short period has attracted the attention of scientists around the world.
In near future, we can see Perovskite-based solar power system installed on the rooftops of the home-owners.