1. Physics
Energy Flow and Conservation of resources
SOLAR ENERGY

2. What is solar energy???
Solar energy is the ultimate source of energy from millions of years and it is a renewable energy.
This energy consists of radiant light and heat energy from the sun. The sun is an inexhaustible an pollution free source of energy.
Out of all energy emitted by sun only a small fraction of energy is absorbed by the earth.
Just this tiny fraction of the sun’s energy that hits the earth is enough to meet all our power needs.
Using present solar techniques some of the solar energy reaching the earth is utilized for generating electricity etc….
Even then the energy demand met by using solar energy is very less.

3. HOW IS SOLAR ENERGY USED??
We can use solar energy by converting it to electrical energy . So we must use a device called solar panels which can convert the light energy into electrical energy.
Solar panel is a group of solar cells.
Solar cells works on the principle of photoelectric effect.
PHOTOELECTRIC EFFECT
When a light of certain frequency falls on the surface of a metal , electrons will absorb the energy . If incident light energy is greater than the work function(minimum energy required to remove the loosely bound valence electrons)of the metal ,then the photo electrons will be emitted and the excess energy is converted to the kinetic energy of electron

4. SOLAR PANELS
Solar electric panels are made up of something called silicon, the same thing that makes up sand.. Even though you can find silicon almost everywhere, making a solar panel is difficult and expensive. The silicon has to be heated to super high temperatures in a big factory, and then formed into very thin wafers. When sunlight hits a solar panel, it makes electrons in the silicon move  around. The electrons flow through wires that were built into the solar panel. We can do whatever we want with this electricity, run a calculator, a CD player, or, if we have big enough solar panels, a satellite! [Solar panels are also called photovoltaic panels. "Photo" means light and "voltaic" means electricity

5. USES OF SOLAR ENERGY Heaters Green houses Cars water pumps
Lights Desalination
Satellites Chilling
Dryers Solar ponds
Calculators Thermal
Commercial use
On an office building , roof areas can be covered with solar panels .
Remote buildings such as schools , communities can make use of solar energy.
In developing countries , this solar panels are very much useful.
Even on the highways , for every five kilometres ,solar telephones are used.

6. APLICATIONS OF SOLAR ENERGY
Solar car
Solar lights
Solar heater
Solar cooker

7. ADVANTAGES OF SOLAR ENERGY
Solar energy is a completely renewable resource which means that even when we cannot make use of the sun’s power because of night time or cloudy and stormy days, we can always rely on the sun showing up the very next day as a constant and consistent power source.
Initial cost of solar panels and solar lighting may seem quite expensive but in the long run it saves quite a great deal of money. It does not cost anything to harness the power of the sun. Harnessing sun’s energy is absolutely free.
Solar energy creates absolutely no pollution. Solar cells are totally silent and non-polluting.
Very little maintenance is required to keep solar cells running. There are no moving parts in a solar cell so, they require little or no maintenance at all, and have a long lifetime.
Solar powered panels and products are typically extremely easy to install. Wires, cords and power sources are not needed at all, making this an easy prospect to employ.

8. DISADVANTAGES OF SOLAR ENERGY
Installation of solar panels is expensive. Initial investment is high.
Solar energy cannot be harnessed during a storm, on a cloudy day or at night. Some days you may still need to rely on other sources of energy.
Most of the solar devices occupy large space to achieve average efficiency.
The efficiency of solar panels is low comparative to other sources of energy. To achieve equivalent output large equipment is required.
Geographical location and climate of a place can be a source of disadvantage of solar energy. The efficiency of the solar panels is dependent upon the amount of sunlight received.
Air pollution and weather can also have a large effect on the efficiency of the cells.
Do not get same efficiency on all the days and during every season as the intensity of sun’s light changes with season

9. IMPORTANCE OF SOLAR ENERGY
Solar energy is an important part of almost every life process, if not, all life processes. Plants and animals, alike, use solar energy to produce important nutrients in their cells. Plants use the energy to produce the green chlorophyll that they need to survive, while humans use the sun rays to produce vitamin D in their bodies. However, when man learned to actually convert solar energy into usable energy, it became even more important
Solar energy cells can be used to produce the power for a calculator or a watch. They can also be used to produce enough power to run an entire city. With that kind of versatility, it is a great energy source.

10. BETTER WAYS OF USAGE
Government should take measures and see that solar lights are used as street lights in all the areas.
We can place solar panels in the barren lands instead of keeping it away uselessly.
We can also keep these solar panels in the deserts , where we can make use of this energy with the help of a rechargeable battery.
Efficiency of solar panels depends on the range of frequencies of light that strikes the surface . So they can give higher efficiency if we split the light into different frequency ranges and direct the beams onto the cells tuned to these frequencies.
Building a new home is the best time to design and orient the home to take the advantage of the sun’s rays.

11. THE END