What is Solar energy?
By Dilys & Doug Griffiths - 03/03/2008
Solar energy is energy obtained from the sun and it can be used in three ways:
(1) Using photo-voltaic cells (PV cells)
(2) Water heating systems
(3) Creating hot air flow systems.
Let’s take a look at Photo-voltaic (PV) cells.
When we take a stroll on a sunny but cold winter’s day, it is comforting to feel even the slightest warmth from the pale sun. Hunched up behind our woolly scarves, we would surely find it difficult to imagine how intense this same sun can be in a desert.
But, I promise you, if we were able to take our stroll in a desert its more than likely we would soon stop in our tracks to gaze in amazement at what lies before us. There’s things happening in them there sand hills!
Let's take our stroll through some of the deserts in U.S.A., where there are many sorts of experiments going on. We may suddenly come upon long lines of curved mirrors all facing into the blazing sun. Each mirror is set to focus the sun’s rays on to long lines of water pipes. The idea behind this lot is to heat up the water in order to produce steam and use it to drive turbines. These machines, in turn, will drive electric generators.
Strolling through another desert we might stumble upon a very large mass of square panels, set in long lines, all facing the blazing sun. Each panel measures about a metre or more and is made up of small two -inch cells. These may look like framed masses of bee’s eyes –some round and even some square-eyed bees at that! Actually, these are PV cells, hundreds of thousands of them.
What is a PV cell? It varies in size from minute to about as big as a matchbox. And if you could look inside you would find it’s made up of even more cells. Basically it’s made up of a metal plus lots of other elements.
Each PV cell can generate a small amount of electricity even on a dull day. Imagine what this large gathering of cells can produce! In a tropical region, if we covered an area 110 miles by 110 miles with these ‘busy bees eyes’ they, could produce enough energy from the sun to supply the whole of Europe’s present energy needs, with a little bit left over.
In Britain these days we buy energy by importing and eventually burning coal, oil and gas from areas all over the world. Why don’t we obtain our energy from the many deserts we have on our planet? Then there would be no nasty waste gases to worry our heads over!
There is an international group of scientists and engineers who are, currently, seeking solutions to the problem of transmitting large amounts of electrical energy from deserts to populated areas. If we could only achieve the aid and political backing of major large Countries, this could become a reality within the next two decades. Let’s all live in hopes.
From the potential giants to the ‘mighty midgets’, lets think about a bank of PV cells sitting on the roof of your house. Did you know, even with only our pale winters sun, you can have a supply of energy to cover from one quarter to all of you household’s needs, depending on your roof’s size and its position to the sun. Setting this up would cost £8,000 to £14,000.
Present Government Grants can reduce these figures by a large amount and are worth considering; especially now those fossil fuel prices are rising. In this country there are only a few winter days, when power is unable to be generated. For this reason, British scientists and engineers are busy looking at means of storing energy.
One of the most promising means is to use the electricity obtained in the sunshine, to split up water, held in large tanks, into its two component elements and produce oxygen and hydrogen. The hydrogen produced can be stored and used at a later date as a gas, for cooking, heating or regenerating electricity. The oxygen can be sold as a by-product. Some States in Southern America have several working examples of this method but here in Britain the plans continue to be experimental.
PV cells are already a common sight on our road signs. Solar lights for our gardens are selling like hot cakes, as are porch and security lights. On a larger scale some factory and house-heating apparatus is already installed. One school is using these cells for its main source of energy. Mobile phones, computers, cameras, calculators, toys to name but a few can be powered by PV cells…..What next?
Using our sun for power is no new thing. Legend has it that in 212BC a Greek Philosopher, Archimedes, used polished bronze shields to focus the sunlight on to enemy wooden ships in an attempt to set them alight. The result is unknown but certain people, in the Greek Navy, repeated this experiment in the early 1970s and actually set fire to a boat some 50metres away! I believe there were no passengers aboard.
During the 16th century Leonardo da Vinci proposed using mirrors to heat water. There is no record of this ever having been done.