You don’t have to know how rooftop solar panels work in order to get the benefits of clean electric power from them, but the more you know about it, the more informed decisions you’ll be able to make. For instance, when we talk about solar energy, there are a few distinctly different technologies at play, such as solar thermal (concentrating and storing the heat from the sun’s rays) or solar water heating (basically solar thermal systems in which the heat-storing element, the water, is used directly and then replaced), but when the topic comes to home solar, the technology is solar photovoltaic, or solar PV.
Because the photovoltaic effect is at the heart of solar cell technology, it’s probably the most complex element of home solar that you’ll come across, simply because all the action happens on a scale that can’t be seen by the human eye. We can see that it’s sunny out and that the sun’s light is hitting the surface of the solar panel, and then go verify that electricity is flowing out of the array, but most of us have no idea what happens between those two points.
Here’s a technical description of the photovoltaic effect, courtesy of Wikipedia:
“When the sunlight or any other light is incident upon a material surface, the electrons present in the valence band absorb energy and, being excited, jump to the conduction band and become free. The chemical bonds of the material are vital for the process to work, as crystallized atoms are ionized and create a chemical electric imbalance, driving the electrons. These highly excited, non-thermal electrons diffuse, and some reach a junction where they are accelerated into a different material by a built-in potential (Galvani potential). This generates an electromotive force, and thus some of the light energy is converted into electric energy.”
However, if that definition doesn’t quite cover it, the following video attempts to explain what the photovoltaic effect is, in just two minutes, using beer pong. And while you’ll have to overlook the presenter’s pronunciation of the word silicon (which he refers to as silicone, and which is more likely to be found in caulking and sealants than in solar energy discussions), it is one of the most unique ways of illustrating the photovoltaic effect:
Perhaps that was more entertaining than educational, so perhaps this older video, which covers the photovoltaic effect, can shed a little light on the subject:
And finally, if you want just the facts on the photovoltaic effect, here’s this great animated version:
Image: Alan Levine