SOLAR PHOTOVOLTAIC SYSTEMS

Green DIY Energy Ever wonder how a solar cell takes sunlight and converts it to electricity? Whether it be your solar powered calculator which requires very little energy or a remote research facility in the forest that requires a substantial amount of power, the building blocks of solar photovoltaic systems are all same. You take a photovoltaic cell (fancy-science word for solar cell) which generates a tiny amount of electricity and then you connect a bunch of these together and wah-la you have more electricity!..Simple enough?.. ok that’s a seriously simplified explanation, but it is the basics. Follow me I’ll explain more.

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THE SCIENCE OF SOLAR PHOTOVOLTAICS

Ok.. here’s where I need to get a little scientific on you. Photovoltaics is the technological approach where sunlight is converted to electricity (see How Does Solar Energy Work). Another way to look at it is a photovoltaic device is a solar powered battery that consumes the same light that gives it energy.. Confused yet? Hope not.. moving on.. In its native form, the type of electricity created by a photovoltaic system is called direct current (DC..same kind of electricity your car battery stores) In this form it can be easily stored for later use or used directly. Some electrical systems like your car accessories (radio / lights / blinkers etc) require DC, yet most of our home’s electrical devices require AC (alternating current).

The conversion from the stored DC current to AC is done by a unit called an inverter (see Solar Power Inverter).  A simple way to understand the differences between direct current and alternating current is to know that DC is a constant flow of electricity (current) and AC is one that essentially turns on and off at very high rates so to an electrical device it seems like a continuous flow of electricity even though it isn’t.. Ok I probably confused you..sorry.. see the article titled Solar Power Inverter for further explanation.

SOLAR CELL CONSTRUCTION

Now before all this we need to look at the construction of a solar cell which does this magic! The most common type of a photovoltaic cell is one made with semiconductor material which is usually silicon. Now, were not even going to go down the road of P-N junctions and diode formation which make up a solar cell, but basically there are a few layers of semiconductor material which when pressed together creates an important junction. This junction between the layers of semiconductors creates and environment full of electrons that have the capacity to be stimulated by sunlight. This stimulation directly raises their energy level. When their energy level is raised in this environment, electrons begin to flow. The flow of electrons is current. Simple enough? Ok all you electrical engineers and techies reading this, don’t beat me up, I could have spent 3 pages on this alone and put the average reader to sleep!

A single photovoltaic (solar) cell is usually very small and only creates about 1-2 watts of power. Before we have something we can call a solar photovoltaic system, we need to connect many of these solar cells together to form “modules”.  Solar modules of course have higher electrical outputs and are the building blocks of larger units called arrays. I’ll break this down for you further. Think of your solar powered calculator for an example of a solar cell, a unit on top of a emergency telephone on the side of a road as an example of a module, and a the systems you see on residential roofs as an array. Small, medium and super-sized!

Hopefully you have a better understanding of the term solar photovoltaic system. As technological advances increase the efficiency and reliability of these systems we should see a wider acceptance and more prevalent applications.  The continual rise in energy costs and the environmental preservation concerns of our world are going to drive advancements and further research into this technology. The next step are initiatives and incentives like the Federal Solar Tax Credit that are aimed at creating a wider adoption of solar photovoltaic systems as a viable alternative energy source.

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