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• Term "photovoltaic" comes from the Greek ”photos” meaning "light", and from "Volt", the unit of electro-motive force,
• The volt, which in turn comes from the last name of the Italian physicist Alessandro Volta, inventor of the battery (electrochemical cell).
• The term "photo-voltaic" has been in use in English since 1849.
Solar History
Solar Energy
Photovoltaic is technology in producing electricity from light or generation of electricity from sunlight.
Advantages
• Solar energy is free.
• Solar energy does not cause pollution.
• Solar energy can be used in remote areas where it is too expensive to extend the electricity power grid.
• Many everyday items such as calculators and other low power consuming devices can be powered by solar energy effectively.
• It is estimated that the world’s oil reserves will last for 30 to 40 years. On the other hand, solar energy is infinite (forever).
Disadvantages
• Only be harnessed when daytime and sunny.
• Solar collectors, panels and cells are expensive.
• Solar power stations can be built but they do not match the power output of similar sized conventional power stations.
• In UK, the unreliable climate means that solar energy is also unreliable as a source of energy.
• Large areas of land are required to capture the suns energy.
• Solar power is used to charge batteries so that solar powered devices can be used at night. However, the batteries are large and heavy and need storage space. They also need replacing from time to time.
Solar Cell• A solar cell (photovoltaic cell) is an
electrical device that converts the energy of light directly into electricity by the photovoltaic effect.
• current, voltage, or resistance vary when light is incident upon it.
• Materials presently used for photovoltaic solar cells;– Monocrystalline silicon– Polycrystalline silicone– Amorphous silicon– Cadmium telluride– Copper indium selenide/sulfide
A solar cell made from a monocrystalline silicon wafer
A monocrystalline solar cell
• The diagram shows basic photovoltaic cell. • Blue color show main material, silicon. • Black round and irregular shapes represent the impurities of boron or
phosphorous. • Sun/light strikes the cell the impurities free up electrons which ‘bounce’
around at incredible speeds. This creates an electrical charge.
Solar Cell Work
• Silicon is a material known as a ‘semiconductor’ as it conducts electricity and it is the main material for photovoltaic cells.
• Impurities such as boron or phosphorus are added to this base material.
• These impurities create the environment for electrons to be freed when sunlight hits the photovoltaic panel.
• The freeing of electrons leads to the production of electricity.
Solar Cell Work
• V = 0.5V
• I = 3.4A
• P = I x V = 1.7Watt
• Efficiency = 17%
• Sun radiation = 1000W/m2
Solar Cell Specification(+)
(-)
Solar Cell Efficiency
• Assemblies of photovoltaic cells are used to make solar modules which generate electrical power from sunlight.
• Multiple cells in an integrated group, all oriented in one plane, constitute a solar photovoltaic panel or "solar photovoltaic module“.
• The electrical energy generated from solar modules, referred to as solar power, is an example of solar energy.
• A group of connected solar modules is called an "array."
Solar Panel
Polycrystalline photovoltaic cells laminated to backing material in a
module
Solar Application
Early solar powered calculator
Solar panels on the space station absorb light from both
sides.
Electronic application
Solar powered vehicle
Solar powered vehicle• The Department of Sustainability and
Energy Management as a plug-in electric vehicle from University of Central Florida.
• The 3 solar panels attached to the roof, runs on 100% solar power.
• Per day, the car can go about 15 miles, which doesn't seem like much, but for just traveling around campus, its perfect.
• Two of the panels power a 48V charge controller, and the panel powers a 24V charge controller, which is enough to get the car going.
• Essentially operation of the car is carbon neutral - no fuel, no plugging into a station and no emissions.
Solar powered vehicle
• Solar powered golf cart and it can be used in sunny climates to carry golfers from one hole to the next.
• When it is standing still the solar panels charge up the batteries and it is the batteries that power the electric motors, directly.
• As the vehicle is not in continuous use the batteries have time to charge up before they are needed
Solar powered vehicle
• Solar powered cars could become practical is to charge up their batteries when they are parked, during the day.
• Imagine driving the short distance to work and plugging the car into a set of photovoltaic solar panels.
• Whilst you are working the batteries charge up ready for use for the journey home. The same procedure could be carried out when the car is parked at home.
Solar powered vehicle
• These are expensive to produce and usually seat only one or two people. The main cost is due to the large number of expensive and delicate photovoltaic solar panels that are needed to power the vehicle.
• Many of the solar powered cars used in races today are composed of expensive, lightweight materials such as titanium composites. Carbon fiber and fiber glass are also used for much of the bodywork. Most of the cars used in races are hand made by specialist teams and this adds to the expense.
Solar powered vehicle
• A solar powered vehicle can only run efficiently when the sun shines, although most vehicles of this type have a battery backup.
• Electricity is stored in the batteries when the sun is shining and this power can be used when sun light is restricted (cloudy).
• The batteries are normally nickel-metal hydride batteries (NiMH), Nickel-Cadmium batteries (NiCd), Lithium ion batteries or Lithium polymer batteries.
• Common lead acid batteries of the type used in the average family car are too heavy. Solar powered cars normally operate in a range of 80 to 170 volts. To reduce friction with the ground the wheels are extremely narrow and there are usually only three.
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