Solar panels and solar cells
P H Y S I C S P R O J E C T.
SOLAR PANELS & SOLAR CELLS
By Hammaad Khalil
25th December 2002
Set 1
CONTENTS
* Introduction
* How solar panels and solar cells are
made and how they work.
* Where they are used (examples).
* Why they are used?
* Solar Cells.
* Conclusion
SOLAR PANELS
SOLAR PANELS AND SOLAR CELLS.
Introduction.
Solar panels and Solar cells basically come from solar energy (energy from the sun). You have probably seen calculators that have solar cells and don't even have an off button. Solar panels are used everywhere as well. For example they can be found on emergency road signs and call boxes. Although these larger solar panels aren't as common as solar powered calculators, they still do the same job and are out there and not hard to spot if you know where to look. Solar cells are even used on satellites to power the electrical systems.
You have probably even heard of people saying that they will start to use solar energy to power homes and offices, as this energy is completely free. On a bright sunny day the sun shines approximately 1,000 watts of energy per square meter of the planet's surface and we could collect all that energy and use it to power our homes and offices.
How Solar panels and Solar cells are made and how they work?
The solar cells that you see on calculators and satellites are photovoltaic cells or modules. Photovoltaic, as the word implies (photo is light, voltaic is electricity), convert sunlight directly into electricity. They could even power your house.
The solar panel is the basic building block of the system. This is your battery charger. If you have several solar modules wired together you have created a solar array. The size of the solar array determines the amount of power or energy that will be produced. Your location is also a factor in the amount of energy produced. If you live in Florida, Southern California, or
Texas you will produce more than if you live in Oregon, Maine or Maryland. In general the closer to the equator you live your system will produce a larger ...
This is a preview of the whole essay
The solar panel is the basic building block of the system. This is your battery charger. If you have several solar modules wired together you have created a solar array. The size of the solar array determines the amount of power or energy that will be produced. Your location is also a factor in the amount of energy produced. If you live in Florida, Southern California, or
Texas you will produce more than if you live in Oregon, Maine or Maryland. In general the closer to the equator you live your system will produce a larger amount of energy. Photovoltaic (PV) cells are made of special materials called semiconductors such as silicon, which is currently the most commonly used. Basically, when light gets to the cell, and some of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor.
When light hits the solar cell, its energy is transformed into a current, and the cell's electric field causes a voltage. With both current and voltage, we have power, which is the product of the two.
Operation of a PV cell
Unfortunately the most our cell could absorb is around about 25 percent of the solar energy.
Where are they mainly used? (Examples)
Solar Panels and Solar cells are mainly used to help power buildings and homes. They can be used almost everywhere. Even in space an example is the Hubble telescope using solar panels:
General schematic of a residential PV system with battery storage
Why are they used?
Solar panels and solar cells are mainly used as they are renewable sources of energy they do not cost a penny until they are installed. After paying the initial cost you don't have to pay anything. All the energy comes from the sun and is converted into electricity for you to use at home. An example of a solar powered house is in America, it is called the, 'North Carolina House':
Solar
Panels
From this we can see how cost effective solar energy could actually be. Even though the initial cost is a lot you don't pay after the installation is complete. It's like it's almost free!
Solar panels that are fitted facing south are very effective.
There are two types of solar energy these are:
Active Solar Heating - Solar water heating panels use the heat of the sun to warm water directly, usually to provide domestic hot water. Once installed, a system requires very little maintenance and should last for decades, but it cannot provide all your hot water needs year-round, so a back-up system will be needed. Solar water heating is best regarded as a fuel saving measure, and can typically save about half of your water heating bills. For more information on solar water heating please refer to our book 'Tapping the Sun'. Some commercially installed systems can be quite expensive and it is worth getting several quotes. Costs can be reduced by installing a system yourself, or even by building your own panels. Our publication, 'Solar Water Heating: A DIY guide' explains how to design and install your own system.
Solar water heating panels work best on sunny days, but still contribute something to your hot water demand when it is cloudy. Solar water heating is very effective at providing heat for swimming pools. However in the British climate they cannot really make any useful contribution to your space heating needs.
Passive Solar Design - every house gets some of its heating requirements from the sunlight that falls on the outside of the house. When designing a new house, it is possible to arrange the design to make the best possible use of this effect, and so to reduce the amount of heating required by 50%-80%. The most common elements of passive solar design include:
* increasing the amount of glazing (the size of the windows) on the south face of the building
* using thermally efficient glazing (double glazed, argon filled, low-e glass)
* decreasing the amount of glazing on the north
* adding a solar heating space, such as a conservatory
* including heavy materials, such as masonry, to store up solar energy for use at night
* arranging the house ventilation system to make best use of the solar heating elements
* maximising insulation to reduce heat loss
* Finding a suitable place for the house to increase the amount of sunlight hitting it.
* providing shading to control excessive heat gains in summer.
Solar Cells
Solar cells convert solar energy into electricity as well. A solar cell contains solid substances such as silicon; solar radiation entering these substances frees electrons from the atoms of these substances to produce electricity. These are mainly used in satellites and calculators. Solar powered vehicles can be seen on the market nowadays.
A Honda Solar Powered Car.
Solar Water Heating
Over 44,000 solar water heating panels have been installed in the UK. Solar panels contain water which is heated by the sun, and this then usually goes through a coil in a hot water cylinder, transferring the heat to the water there. (If wood comes from managed forests, it is potentially a renewable fuel and is carbon neutral as it absorbs the same amount of carbon dioxide when growing as it gives off when burnt. It is important that wood is well seasoned and burnt efficiently, or it will give off harmful toxins.) In most cases solar water heating panels will not provide space heating because there is not much sun in the winter, when you need heating the most.
Conclusion.
So it seems to me that Solar panels and solar cells are a marvellous way to generate electricity and power everyday things. Examples as given above are things like the solar panelled car; house and even satellites use them in space. It is an extremely generous thing to do if you install a solar panelled heating system in your home as you are contributing as a member to save the ozone layer. And another advantage is that you are not paying a penny after you have had the system installed.
