Within the paradigm of energy engineering, efficiency improvement can be intensive, laborious and a painfully slow process. Products like internal combustion (I.C) engines have seen marginal efficiency gains over the last century. The best I.C. engines today do not go beyond 18% efficient. The research and development period for this machine stretches well over a century. And that too by hundreds of research institutes and manufacturers all over the world. Coal fired power plants similarly have peaked at 44% despite been in use for more than two centuries.
By contrast Solar Cell technology has made rapid gains in the last 50 years. Commercially available solar panels today have efficiency that surpasses 30% , meaning almost a third of the light (photon) energy falling on the solar panel is converted into electricity. And yet, there has arrived a new technology (within the solar cell umbrella) which has seen an unparalleled progress compared to established technologies in the category. Such has been the advancement that almost all Solar cell researchers are looking into it.
It is the Perovskite cells that have caused great excitement in the solar energy community. It has been reported that lab efficiencies for this type of cell have already crossed 19% within a period of 5 years. It should be noted that crystalline silicon cells took almost 65 years to reach this level.
This raises two pertinent questions: why if Silicon panels of 23% efficiency are already selling in the market, than other options are being researched? Why Perovskite cells, despite their lower efficiency compared to the top rated cells in the market, are causing such a buzz?
The reason is that Silicon cell price has dropped more than 100 times compared to their price in 1977 (from $0.74/W to $76.67/W), however their current price still makes PV systems out of reach for many people in the developing world. As Silicon needs to have 5C purity (99.999%) and the process requires heating Silica to about 1600 °C, this raises the cost of silicon based solar panels substantially. Perovskite cells on the other hand can be made at room temperature.
Already companies like Oxford Photovoltaic are hinting that Pervoskite panel can hit the market within 5 years’ time. These panels will be able to provide efficiency comparable to, if not more than silicon panels. Moreover, they will be available at a price that matches thin-film panels. It should be noted that Thin-film panels are cheaper than Silicon panels (by almost 30%), however their efficiency is also much lower.
There are certain factors that have made silicon the king. Firstly Silicon semiconductor are being used in the electronics industry and therefore the presence of infrastructure has helped Solar industry. Silicon used in electronics is even more pure than solar (purity level is 7C i.e. 99.99999% pure). However compared to the use in solar panel, the quantity of silicon used in electronics is fractional. The second factor that has buoyed silicon based solar cells is that it is the 2nd most abundant element on the earth’s crust.
For Pervoskite cells, the process of development is fairly simple and inexpensive, however there is the question over its availability. So far it has been found in Germany, Switzerland, Sweden, Italy, USA and Russia. It is certain that it may never be abundant as Silicon but may be still enough to revolutionize solar industry.
There were reservations regarding Pervoskite longevity and reaction to moisture. These have already been answered by researchers, who have found solutions for increasing its life. At a time when solar cells of most technology have already plateaued, the arrival of Perovskite cells has breathed a new impetus in the solar industry. Pervoskite tandem cells are poised to be the next big thing in the renewable energy arena and present a valuable investment opportunity for financiers.
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