4. The sun
yellow dwarf star in the center of the solar system
diameter = 1,392,000 km, 109 times of earth’s
mass = 2×1030kg, 330,000 times of earth’s
99.86% of the solar system’s total mass
¾ hydrogen, the rest is mostly helium
primary source of energy in the earth
6. solar energy
the earth receives 174 petawatts [1015 watts] from the sun
30% is reflected into space and the rest is absorbed by land,
oceans, clouds etc.
the total energy absorbed by earth’s atmosphere, oceans, land
mass is 3,850,000 exajoules [1018 joules] per year
energy entering the earth from the sun is twice the energy
harnessed from all non-renewable sources of energy combined
8. photovoltaic's
generating electrical power by converting solar radiation
into dc electricity using semiconductors that exhibit the
photovoltaic effect
The photovoltaic effect is the creation
of voltage or electric current in a material upon exposure
to light
first observed by Alexandre-Edmond Becquerel in 1839
9. the photovoltaic cell
also called solar cell, is an electrical device that converts
the energy of light directly into electricity by
the photovoltaic effect
made of monocrystalline silicon or polycrystalline
silicon or amorphous silicon or cadmium telluride,
or copper indium selenide/sulfide
first built by Charles Fritts in1883 by coating
the semiconductor selenium with an extremely thin layer
of gold
10. the photovoltaic cell cont.
photons in sunlight hit the solar panel and are absorbed
by semiconducting materials, such as silicon
electrons are knocked loose from their atoms, and
current starts flowing through the material and this
electricity is captured
an array of solar cells converts solar energy into a usable
amount of direct current [DC] electricity
13. Difference between renewable energy and
non-renewable energy
Renewable energies are the energies that
never run out, they don't pollute our
planet and some of them produce a lot of
energy. Examples: wind energy, solar
energy... And non-renewable energies,
are the energies that in a day they run
out, and they pollute a lot our planet.
14. Why we need to use renewable energy?
Many forms of energy that we have grown dependent on
are from non-renewable energy sources. This means that
when the energy has been consumed, the supply has
gone and cannot be replaced. An example of this is coal.
Coal is known as a fossil fuel and is the largest source of
energy for the generation of electricity worldwide. When
coal has been mined and burnt, it cannot be replaced.
Finding alternative energy sources, ideally from
renewable sources, will decrease our dependency on
fossil fuels and other non-renewable energy sources.
16. advantages
solar energy is a renewable source of energy
in the presence of solar power, use of non-renewable sources of
energy like petroleum can be lessened which also lessens pollution
an array of solar cells converts solar energy into a usable amount
of direct current [DC] electricity
Though solar panels are expensive, the total amount that would be
saved makes the price of the panels will seem small
17. disadvantages
solar panels are expensive
solar power is inefficient in cloudy areas
batteries and solar panels occupy more space ( Need more spaces )
solar power maintenance is a problem
disposal is difficult for the batteries and solar panels when they have
broken down because they contain toxic chemicals like lead, sulfuric acid &
cadmium telluride
