Tuesday, November 25, 2014

PV electricity generation is not that complicated

The process of generating electricity with a photovoltaic solar system is not as complicated as many people think it is. It's actually a rather simple process that consists of several different principles. The basic principle is at follows; once the sunlight hits the surface of the PV panels the electrons in the solar cells get activated. The activation of electrons means that they start to move with much bigger frequency, and in the process they start to bump into each other more frequently. This interaction between the electrons is what generates electricity.

A solar (photovoltaic) panel or module consists of large amount of individual solar cells. If we were to simplify things we could say that solar cell is primarily silicon with some circuitry. The more cells there are in a solar panel, the more electricity it can generate. A string of panels makes up an array and multiple arrays comprise a solar PV system.

If we were to divide things even further we could say that PV system is only one form of harnessing solar energy. For instance, hot-water system is used specifically to heat water while A Concentrated Solar Power system (CSP) uses mirrors to focus sunlight on water, causing it to boil producing steam, which is then used to generate electricity.

PV systems are in most cases connected to the grid with the only real exception here being people in more remote locations where a battery back-up system is often lot more practical. Two primary types of solar panels are mono-crystalline and polycrystalline.

Silicon is the primary material used in solar panels as the main active material in a solar cell, primarily because of its unique chemical properties. A silicon atom is comprised of twelve electrons on three separate 'shells' or layers. The outermost 'shell' has four electrons that are highly reactive. The outer electron shell of a silicon atom is seeking to reach of state of equilibrium by 'sharing' its electrons with other atoms. Conversely, those other atoms will share their electrons as well.

These electrons are always moving but the energy from the sun causes their rate of movement and interaction to increase. By bumping into each other more frequently they generate friction and this is what generates electrical energy. After this phase it is only a matter of channeling the current through all the wiring to the inverter. The inverter is needed to convert the electricity from direct current to alternating current because our electrical grid is not designed to handle direct current. In a grid tied system any excess current is supplied back to the grid. In off-grid PV system there is usually a battery back-up system to store excess current generated by the system for later use.

Generating electricity from the sun is a very practical way to meet our electrical demand, especially because solar panel prices have decreased by more than 70% in the last five years. This particularly applies to remote and isolated areas where using PV panels to generate electricity is far more efficient than rebuilding entire energy grid.

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