Solar energy

CONTENT
• Basic Principle
• Construction
• Working
• Solar Radiation
• Measurement & Calculation
• Types of Solar panel
• Application

SOLAR ENERGY
WHAT IS SOLAR ENERGY ?
• Originates with the thermonuclear fusion reactions occurring in the sun.
• Represents the entire electromagnetic radiation (visible light, infrared, ultraviolet, x-rays,
and radio waves).
• Radiant energy from the sun has powered life on Earth for many millions of years.

SOLAR ENERGY
ADVANTAGES :
• All chemical and radioactive polluting by products of the thermonuclear reactions remain
behind on the sun, while only pure radiant energy reaches the Earth.
• Energy reaching the earth is incredible. By one calculation, 30 days of sunshine striking the
Earth have the energy equivalent of the total of all the planet’s fossil fuels, both used and
unused!
DISADVANTAGES :
• Sun does not shine consistently.
• Solar energy is a diffuse source. To harness it, we must concentrate it into an amount and
form that we can use, such as heat and electricity.
• Addressed by approaching the problem through:
1) collection, 2) conversion, 3) storage.

SOLAR ENERGY AS A RESOURCE
SOLAR ENERGY IS INCREASINGLY BEING USED AS A RESOURCE IN THE FOLLOWING AREAS:
• Architecture
• Urban Planning
• Agriculture
• Horticulture
• Heating, Cooling and ventilation
• Cooking
• Fuel Production
• Electricity Generation

SOLAR ENERGY
SOLAR ENERGY CAN BE USED TO GENERATE ELECTRICITY IN 2 WAYS
• THERMAL SOLAR ENERGY :
Using solar energy for heating fluids which can be used as a heat source or to run
turbines to generate electricity
• PHOTOVOLTAIC SOLAR ENERGY :
Using solar energy for the direct generation of electricity using photovoltaic
phenomenon.

TYPES OF SOLAR ENERGY
• Passive solar energy
• Active solar energy
• Photovoltaic solar energy
• Solar thermal energy
• Concentrated solar power

SOLAR PANEL
• Solar panel is an indispensable component of this system
• Solar panel is responsible to collect solar radiations and transform it into electricity
energy
• Solar panel is an array of several solar cells (Photovoltaic cells)
• The array can be formed by connecting them in parallel or series connection depending
upon the energy required

SOLAR CELL
• A structure that converts solar energy directly to DC electric energy.
• It supplies a voltage and a current to a resistive load (light , battery, motor)
• Power = Current * Voltage = Current 2 * R = Voltage 2 / R
• It is like a battery because it supplies DC power
• It is not like a battery because the voltage supplied by the cell changes with changes in
the resistance of the load

SOLAR PANEL SPECIFICATIONS
MECHANICAL SPECIFICATIONS :
• SOLAR CELL TYPE : Cell used in the module . E.g. : Mono- Si, Poly – Si
• CELL DIMENSION : The size of the cell used in the module. E.g. 125 (1) 125mm (5 inches)
• MODULE DIMENSION : The size of the Panel
• MODULE WEIGHT
• GLAZING OR FRONT GLASS : Type and width of the front glass used.
• FRAME : E.g. Anodized aluminium alloy
• OUTPUT CABLE : Type of cable and their dimensions provided at output to connect with
connector specifications
• JUNCTION BOX : Protection level of electrical casting at the back of panel

ELECTRICAL SPECIFICATIONS :
• PEAK POWER (W) : Defines the maximum power of the panel
• OPTIMUM OPERATING VOLTAGE : Defines the highest operating voltage of panel at the
maximum power at STC.
• OPTIMUM OPERATING CURRENT : Defines the highest operating current of panel at the
maximum power at STC
• OPEN CIRCUIT VOLTAGE : Defines the output when no load is connected under STC
• SHORT CIRCUIT CURRENT : Defines the protection level of electrical casting at the back of
panel. Also includes the no of bypass diodes
• I – V CHARACTERISTICS : Define the current and voltage variation for the panel

ELECTRICAL SPECIFICATIONS :
• MODULE EFFICIENCY : Defines the conversion efficiency given by a given module
• OPERATING TEMPERATURE : Defines the range of temperature for which the module can
function
• MAX. SERIES FUSE RATING : Defines the max. current which can be handled by the
module without damage.
• POWER TOLERANCE : Defines the range of power deviation from its stated power rating
due to change in its operating condition.
• PARAMETERS DEFINED UNDER NOCT : These parameters are same as defined under STC
conditions with different values.
• Temperature Coefficients

SOLAR PANEL WORKS
• Sunlight hit the solar panel and absorbed by semi conducting material such as silicon
• Electrons are knocked loose from their atoms , which allow them to flow through the
material to produce electricity. This process is called the photovoltaic effect
• An array of solar panel converts solar energy into DC electricity
• The DC electricity enters an inverter
• The inverter turns DC electricity into 120 volt AC
• The AC power enters the utility panel in the house.
• The electricity is then distributed to appliances or lights in the house

SOLAR PANEL WORKS
• When more solar energy is generated it can be stored in a battery as DC electricity and
will continue to supply your home with electricity in the event of a power blackout or at
night time
• When the battery is full the excess electricity can be exported back into the utility grid, if
your system is connected to it
• Utility supplied electricity can also be drawn from the grid when not enough solar energy
is produced
• The flow of electricity in and out of the utility grid is measured by a utility meter, which
spins backward by a utility meter, which spins backward and forward
• The two are offset ensuring that you only pay for the additional energy you use from the
utility company. This system is referred to as “net metering”

SOLAR ENERGY
SOLAR COLLECTOR POSITION :
The optimal tilt angle for solar panel for a certain month / season is based on :
• Season
• The location ( North / South) on the planet

SOLAR THERMAL DESIGN
• PV panel will collect the solar energy and convert it
into electricity to be stored within the battery
• The battery will operate the pump device which will
force liquid through the system
• The liquid runs through the solar collector, collecting
heat from the sun and then flows through the worm
bin transferring heat to the compost
• Thermostat will be used to control the temperature
and keep the worm bin within the desired range

SOLAR THERMAL DESIGN
DESIGN POSITIVES :
• Simple design
• Inexpensive
DESIGN NEGATIVES :
• Complicated piping system
• Leakage may crate overall energy losses, Environmental concerns, and even safety
hazards
• Difficult to build
• May need to hire experts for help to build the system

SOLAR AIR COLLECTOR DESIGN
• The collector portion will be attached to the roof
• Tubes or pipes will run down from the collector portion to the worm bin
• Two PV panels will be used to collect energy and power a fan
• The fan will circulate warm air flow to the worm bin

SOLAR AIR COLLECTOR DESIGN
DESIGN POSITIVES :
• Extremely efficient
• Only 2 PV panels required
• Inexpensive
• Material are easily obtainable
DESIGN NEGATIVES :
• Design will not be able to run on cloudy days
• Design will only run for an average of three hours per day

SOLAR RADIATION
• The sun emits EM radiation across most of the electromagnetic spectrum
• The sun does, however, emit X-rays, ultraviolet, visible light, infrared and even radio
waves
• When ultraviolet radiation is not absorbed by the atmosphere or other protective
coating. It can cause damage to the skin known as sunburn or trigger an adaptive change
in human skin pigmentation
• The sunlight that reaches the ground consists of nearly 50% visible light, 45% infrared
radiation and smaller amounts of ultraviolet light and other forms of electromagnetic
radiation
• This radiation can be converted either into : thermal energy or into electrical energy.

SOLAR RADIATION
SOLAR RADIATION COMPONENTS :
• Ultra – Violet ( 200nm to 400 nm) 8.7 % ,
• Visible (400nm to 700nm) 36.2 % ,
• Infra – red ( 700nm to 2500nm ) 53.78 %
• Near infra – red ( 700nm to 1100 nm) 28.1 %
• Infrared/ far – infrared ( above 1100nm) 25.4 %
SOLAR RADITION LEVEL:
• Average radiation outer space 136.7mw / sq.cm
• Radiation on earth surface.

SOLAR RADIATION GEOMETRY
ANGELS USEFUL IN SOLAR RADITION ANALYSIS :
• Latitude of Location (φ1)
• Declination (δ)
• Hour angle (ω)
• Altitude Angle (α)
• Zenith Angle (θz)
• Solar Azimuth angle (ϒs)
• Slope (s)

LATITUDE OF LOCATION (Φ1) :
• Angle made by radial line joining
the location to the centre of the
earth and the projection of that
line on the Equatorial plane
• It is the angular distance north or
south of equator measured from
centre of Earth.
• It varies from 0° at equator to 90°
at the poles.

DECLINATION (δ) :
• Angular distance of the sun’s rays
north or south of the equator.
• It is the angle between a line
extending from the centre of sun to
centre of earth and the projection of
this line upon Earth’s Equatorial Plane
• It is due to tilt of Earth’s axis and it
varies between 23.5° (summer solstice
: June 22) to -23.5° (Winter Solstice
December 22)

HOUR ANGLE (ω) :
• The angle through which the earth
must turn to bring the Meridian of
a point directly in line with the
sun’s rays.
• It is a measure of the time of the
day with respect to solar noon
• At noon , ω = 0. ω =15° per
hour
• It is measured from noon, based
on the local solar time (LST), +ve
before noon and –ve during
afternoon.

LOCAL SOLAR TIME :
Solar time can be obtained from standard time observed on a clock by applying Two
corrections :
• Due to difference in Longitude between a location and the meridian on which the
standard time is based : Has a magnitude of 4 minutes for every degree difference in
Longitude
• Due to Equation of Time : As Earth’s Orbit and rate of rotation are subject to small
perturbations.
EOT = 0.2292 ( 0.075 + 1.868 cos N – 32.077 sin N – 4.615 cos 2N – 40.89 sin 2N)
Where N = (n-1) (
𝟑𝟔𝟎
𝟑𝟔𝟓
) ; n is the day of the year (counted from January 1st)

ALTITUDE ANGLE (α) :
• Vertical angle between the projection of sun’s rays on the horizontal plane on earth’s
surface and the direction of sun’s ray
• The Altitude Angle (α) is maximum at solar noon.

ZENITH ANGLE (θz) :
• Complimentary angle of solar Altitude Angle , i.e. Vertical angle between Sun’s rays and
a line perpendicular to the horizontal plane through the point, i.e. Angle between the
beam from the sun and the vertical.

SOLAR AZIMUTH ANGLE (ϒs) :
• Solar angle in degrees along the horizon east or west of north.
• It is a horizontal angle measured from north to horizontal projection of sun’s rays
• It is consider + ve west-wise

RELATION BETWEEN BASIC SOLAR ANGLES) :
BASIC SOLAR ANGLES:
• Latitude of location (φ1 or l)
• Declination (δ or d)
• Hour Angle (ω or h)
DERIVED SOLAR ANGLES:
• Altitude Angle (α)
• Zenith Angle (θz)
• Solar Azimuth Angle (ϒs)
Cos θz = cos φ cos ω cos δ + sin φ sin δ
= sin α …… (as θz = π/2 - α )
Cos ϒs = sec α (cos φ sin δ – cos δ sin φ cos ω )
Sin ϒs = Sec α cos δ sin ω

SLOPE (S):
• Slope (s) : angle made by the
plane surface with the
horizontal.
It is :
• + ve : for surfaces slopping
towards south
• - ve : for surfaces slopping
towards North

ANGLE OF INCIDENCE (θ) :
When tilted surfaces are involved:
• ANGLE OF INCIDENCE (θ) : Angle between sun rays and normal to surface under
consideration

APPLICATIONS OF SOLAR ENERGY
• A partial list of solar applications includes space heating and cooling through solar
architecture, potable water via distillation and disinfection , daylighting, solar hot water,
solar cooking, and high temperature process heat for industrial purposes.
• To harvest the solar energy, the most common way is to use solar panels.

AGRICULTURE AND HORTICULTURE :
• Agriculture and horticulture seek to optimize the capture of solar energy in order to
optimize the productivity of plants.
• Applications of solar energy in agriculture aside from growing crops include pumping
water, drying crops, brooding chicks and drying chicken manure.
• More recently the technology has been embraced by vendor , who use the energy
generated by solar panels to power grape presses
• Greenhouse convert solar light to heat enabling year- round production and the growth
of specialty crops and other plants not naturally suited to the local climate.

SOLAR LIGHTING :
• Daylighting system collect and distribute sunlight to provide interior illumination
• Hybrid solar lighting is an active solar method of providing interior illumination
• Solar thermal technologies can be used for water heating, space heating, space cooling
and process heat generation
• Solar hot water systems use sunlight to heat water.

WATER TREATMENT :
• Solar distillation can be used to make saline or brackish water potable.
• Solar water disinfection involves exposing water – filled plastic polyethylene
terephthalate bottles to sunlight for several hours.
• It is recommended by world health organization as a viable method for household water
treatment and safe storage.
• Solar energy may be used in a water stabilisation pond to treat waste water without
chemicals or electricity

COOKING :
• Solar cooking use sunlight for cooking, drying and pasteurization. They can be grouped
into three broad categories: Box cookers, panel cookers and reflector cookers.
• A basic box cookers consists of an insulated container with a transparent lid
• Panel cookers use a reflective panel to direct sunlight onto an insulated container and
reach temperatures comparable to box cookers
• Reflector cookers use various concentrating geometries to focus light on a cooking
container.

PROCESS HEAT :
• Solar concentrating technologies such as parabolic dish, through and scheffler reflectors
can provide process heat for commercial and industrial applications
• Evaporation ponds are shallow pools that concentrate dissolved solids through
evaporation
• Clothes lines, clotheshorse, and clothes racks dry clothes through evaporation by wind
and sunlight without consuming electricity or gas

EXPERIMENTAL SOLAR POWER :
• Solar pond is a pool of salt water (usually 1 -2 m deep) that collects and stores solar
energy
• The pond consisted of layers of water that successively increased from a weak salt
solution at the top to a high salt solution at the bottom.
• This solar pond was capable of producing temperatures of 90◦C in its bottom layer and
had an estimated solar to electric efficiency of two percent.
• Thermoelectric or thermovoltaic devices convert a temperature difference between
dissimilar materials into an electric current.

SOLAR CHEMICAL :
• Solar chemical processes use solar energy to drive chemical reactions. These processes
offset energy that would otherwise come from an alternate source and can convert solat
energy into storable and transportable fuels. Solar induced chemical reactions can be
divided into thermochemical or photochemical.
• Hydrogen production technologies been a significant area of solar chemical research since
the 1970s
• Another approach uses the heat from solar concentrators to drive the steam reformation
of natural gas thereby increasing the overall hydrogen yield compared to conventional
reforming methods.
• Thermochemical cycles characterized by the decomposition and regeneration of reactants
present another avenue for hydrogen production

SOLAR CHEMICAL :
• Some vehicles use solar panels for auxiliary power, such as for air conditioning, to keep
the interior cool, thus reducing fuel consumption
• A solar balloon is a black balloon that is filled with ordinary air
• Solar sails are a proposed form of spacecraft propulsion using large membrane mirrors to
exploit radiation pressure from the sun.

MEDICAL USES :
• These include, disinfection and sterilization without the use of chemical. Ultraviolet light
is also used to destroy bacteria and viruses.
• It stimulates the immune system and has shown good results in killing blood borne
pathogens.
• Some micro organisms destroyed by ultraviolet light are bacillus anthracis, salmonella or
food poisoning, shigella dysentariae or dysentery , bacteriophage or E. coil, hepatitis and
influenza.
• Ultraviolet light can be combined with other therapies
• Some kinds of skin conditions can improve with the exposure of ultraviolet light.

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