Thermal energy info

Thermal Energy



Thermal Energy is everywhere. It’s lights up our days. It heats the earth, our bodies and our homes. It dries our clothes and gives us produce like sun-dried tomatoes. All for free! and yet we don't take advantage of these sources. It’s also used to heat water like solar geysers for domestic use or even pools. There are two ways in which water can be heated namely:-


1. Actively, when a conventional heating element within the solar hot water system heats water on hot days.


2. Passively, when water is preheated before it is delivered to the cold inlet of a conventional gas/ electric water heater.

Electric Energy


Electric Energy uses the power of the sun to produce electricity through solar cells, otherwise known as photovoltaics (PV). It can be applied in three ways:


1. Stand-alone / called Solar Home Sytems (SHS)


2. Grid-connected


3. Back-up



Stand-alone: also called Solar Home System (SHS):


A system not connected to the grid. More often than not, these systems are installed in remote areas where there is no utility-supplied power, like remote holiday cottages.


It is often cheaper to install a solar energy system than lay electricity cables to the site. Excess energy can be stored in a battery for use during times where there is no sunshine.



Grid-connected:


A system where utility supplied electricity is connected to the property, but the owners wish to harvest clean, free energy from the sun. Usually in a quest to live a more sustainable, environmentally friendly existence.


Electricity is supplied firstly from the solar energy system, then the connected battery if one has been installed and finally from the grid if there is still a need, all of the above is expensive with the annitial layout, but from there onwards, you profit all they way!

Back-up:


A system connected to an unreliable grid or one of poor quality. These types are usually installed in areas where a lot of power blackouts occur. A small system will service the most important electrical appliances and lights, but a bigger system will be required to keep the fridge running during a blackout.

So, what is solar energy used for then?

 To provide heating & to provide electricity

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Solar Power Your Home For Dummies (For Dummies (Home & Garden))

how does solar work?

How does Solar Cells realy work
The solar cells that you see on calculators and satelites are also called photovoltaic (PV) cells, which as the name implies (photo meaning "light" and voltaic meaning electricity), convert sunlight directly into electricity. A module is a group of cells connected electrically and packaged into a frame (more commonly known as a solar panel), which can then be grouped into larger solar arrays.

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¬Photovoltaic cells are made of special materials called semiconductors such as silicon, which is currently used most commonly. Basically, when light strikes the cell, a certain portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely.

PV cells also all have one or more electric field that acts to force electrons freed by light absorption to flow in a certain direction. This flow of electrons is a current, and by placing metal contacts on the top and bottom of the PV cell, we can draw that current off for external use, say, to power a calculator. This current, together with the cell's voltage (which is a result of its built-in electric field or fields), defines the power (or wattage) that the solar cell can produce.

That's the basic process, but there's really much more to it. You've probably seen calculators with solar cells devices that never need batteries ! As long as there's enough light, they seem to work forever. You may also have seen larger solar panels, perhaps on emergency road signs, power lights on the freeways.

Although these larger panels aren't as common as solar-powered calculators, they're out there and not that hard to spot if you know where to look. In fact, photovoltaics , which were once used almost exclusively in space, powering satellites' electrical systems, are being used more and more in less exotic ways. The technology continues to pop up in new devices all the time, from calculators to lights, cooking, etc.

The hope for a "solar revolution" has been floating around now for decades , and the idea that one day we'll all use free electricity fro¬m the biggest source, which is the sun of course!
On a bright, sunny day, the sun's rays give off approximately 1,000 watts of energy per square meter of the planet's surface. If we could collect most of that energy, we could easily provide power to our homes and offices for FREE, how lovely would that be…?

Solar Power Your Home For Dummies (For Dummies (Home & Garden))

Solar Electricity Handbook, 2010 Edition: A Simple Practical Guide to Solar Energy - Designing and Installing Photovoltaic Solar Electric Systems