Dear Diary. Day 64. Still no communication with the outside world. Confined within these four walls in absolute solitude slowly caving in, I feel delirious, dehydrated, demented. Starting to hallucinate. Seeing stars…no…. solar cells. Clinging onto what iota of sanity I have left. Ever wondered if this is what goes through the mind of a research student? Take what I said, bar solar cells, and that’s actually the mindset of someone who has successfully completed their PhD. The repercussions still linger long after the battle has been won.
Now to take a more serious tone it is time for a more educational blog post so grab a pen, wipe the dust off your notebook and put your thinking caps on. From time to time I’ll include these sort of posts so that my blogs are somewhat informative and not seem like they’ve just been written by a two bit clown (fun fact: I know how to juggle) . You could just do a quick Google search or read them up on Wikipedia but where’s the fun in that? If you’re looking for just straight information without an inkling of light-hearted humour, then you should save some of that hard-earned money and go buy yourself a personality 😛 …just kidding, Wikipedia and/or other sources would be your best bet.
So class, the aim of this blog post is to introduce you to solar cells, the essential components it’s comprised of and what their roles are. I could say a million and one things about solar cells but for the sake of your attention span and sanity, I’ll try to keep it short and concise. Boy, if I were to write like this in formal publications, it’ll be as informative as Where’s Wally (Waldo for my american friends).
Before I digress any further, photovoltaics (PV) is a method used to harness the energy from the Sun and a PV cell, or more commonly known as solar cell, is a device used to convert solar energy into electrical energy. What makes them unique is that these sophisticated pieces of technology are capable of generating electricity without producing any harmful by-products and/or noise. They also operate without requirement of any mechanical moving parts. These points raise a stark contrast, when it comes to generating electricity, between solar cells and the ignition of fossil fuels the latter of which inevitably pollutes the environment with all kinds of harmful gases which in turn makes us humans less human-like and less lively.
The process of photovoltaic energy conversion is extremely intricate and complex and attempting to describe it requires the aid of a thousand books, journals and the sacred spirits of Einstein, Newton and Galileo on mild steroids. However, seeing as I’m an expert in dumbing things down, you will find that putting on your socks in the morning a more mind-boggling process after I explain the keys steps in the operation of solar cells in future posts.
You with me so far? Or did all of that just fly over your head? It helps if you weren’t day dreaming about that work colleague you’d like to….you know ;). Now you know what they do, time to explore the essential components of a basic solar cell required to generate electricity. Every solar cell in existence is at least comprised of the following components:
Base – This component makes up for the bulk of a typical silicon solar cell and is where majority of the incident light is absorbed. The generation of charge carriers by light occurs here which are just excited negatively and positively charged particles known as electrons and holes respectively.
Emitter – This is a thin layer component that is layered on top of the base to form something known as a P-N junction at the base/emitter interface in which charge carriers wiz around and move across. The P-N junction is a whole topic of its own so I won’t overload your brain by elaborating on this subject, not right now anyway.
Front and Back Contact – These metal contacts are used as means of collecting and transporting the light-generated charge carriers from the solar cell to an external circuit so that a current can be generated.
External load – The contacts are connected to an external load to make a fully functioning solar powered circuit. The charge carriers are transported here where they dissipate their extra energy as the load consumes the power. Try to remember what you were taught in your physics class about circuits some odd years ago. Where there’s current and voltage, there’s also the dreaded resistance as well. Power is also dissipated in these parasitic resistances as well.
And hey presto, electricity is generated to make your tiny little hair follicles stand. Of course this is a pretty vague description of a how the most basic solar cell operates and is something that shouldn’t be presented in a conference full of world leading pioneering solar cell companies. I wanted to keep it light and humorous but I do plan on making future posts entailing a more in-depth understanding of how solar cells operate. But in the meantime, I’ll return with some more terrific tales from my extravagant adventures as a research student.
(Image taken from: http://www.pveducation.org/pvcdrom/solar-cell-operation/solar-cell-structure)