Jan 04, 2012— read in full
The sun is the original source of almost all the energy used on Earth.
It provides the energy that drives our weather systems. At the same time, trees and other plant life are sustained by using sunlight to create stored chemical energy through the process of photosynthesis. It is this energy that is released when plant material is burned.
Considering how dependent our planet is on the sun, it should come as no surprise that solar energy is one of the fastest growing energy markets in the world.
What is solar?
The sun’s power can be harnessed using photovoltaic (PV) cells- ‘photo’ meaning light and ‘voltaic’ referring to the production of electricity. They work by adapting certain materials known as semiconductors to release electrons when exposed to light.
One of the most common of these semiconductor materials is silicon (an element found in sand). Silicon is the main material in 98% of solar PV cells made today.
All PV cells have at least two layers of such semiconductors: one that is positively charged and one that is negatively charged. When light shines on the semiconductor, the electric field across the junction between these two layers causes electricity to flow.
The result is that the greater the intensity of light shining on the cell, the greater the flow of electricity.
There are four main kinds of crystalline silicon PV Cells
Monocrystalline: These wafer thin cells are cut from cylindrical shapes or ingots of silicon cast in giant moulds. Because the ingots are round, the square cells are normally cut with corners missing. This means there are spaces on the cell that are not able to process the light, making it less efficient.
Poly or multicrystalline: These cells are made from large blocks of molten silicon, cooled and solidified. They are less expensive to produce than single cells and so are more popular. But some people might argue that they are less efficient.
Thin film: Thin film cells reduce the amount of light absorbing material required to make a solar cell.
This means they are cheaper to process. Thin film PV is efficient in low light conditions and very sturdy.
They are made by coating the cell with layers of silicon and then using a laser to cut out the individual cells.
Hybrid: Made from monocrystalline and thin-film technologies, these cells are very efficient and perform well in poor light conditions.
Usually, solar panels have a sheet of glass on the front, and a resin case behind to protect the semiconductor wafers from the weather. The solar cells are then connected in series in modules, so that their voltages add together.
Connected or Off Grid?
Depending on how much energy your PV cells generate and you use, you may have different system needs.
These are the main system options for anyone installing a PV cell:
Grid Connected: This is the most popular type of solar PV system for homes and businesses. The solar system is connected to the local electricity network allowing any you to sell any solar generated electricity you produce but don’t use to the network. Electricity is taken back from the network outside daylight hours. An inverter is used to convert the DC power produced by the solar system to AC power needed to run normal electrical equipment.
Grid Support: The solar system is connected to the local electricity network and a back-up battery.
Any excess solar electricity produced after the battery has been charged is then sold to the network. This is ideal for use in areas where power supply is unreliable.
Off-Grid: Become completely independent of the grid and connect your solar system to a DC Battery. This stores the electricity generated and acts as the main power supply. An inverter can be used to provide AC power, enabling the use of normal appliances without mains