basics of solar energy

1. Basics of Solar
Energy
BY –
SHUBHAM RISHAV

2.  Solar energy is the radiant light and heat from the sun that has been
harnessed by humans since ancient times using a range of ever-evolving
technologies.
 The Earth receives 174 Petawatts (PW) of incoming solar radiation
(insolation) at the upper atmosphere.
 Approximately 30% is reflected back to space while rest is absorbed by
clouds, oceans and land masses.

3.  The spectrum of solar light at the Earth’s surface is mostly spread
across the visible and near near-infrared ranges with a small part in
the near-ultraviolet.
 The total solar energy absorbed by Earth’s atmosphere, oceans and
land masses is approximately 3,850,000 Exajoules (EJ) per year. This is
much more than what the world consumes in a year (500 EJ).

4.  Solar energy refers primarily to the use of solar radiation for
practical ends. However, all renewable energies, other than
geothermal and tidal, derive their energy from the sun.

5. Applications of Solar
Technology
 Solar Power – PV and Solar Thermal
 Solar Lighting (PV Technology for SHS and Solar Lantern)
 Solar Thermal –
a) Agriculture and Horticulture (Greenhouse)
b) Water Heating
c) Space Heating, Space Cooling
d) Water treatment (Solar Desalination)
e) Cooking
f) Process Heating
 Solar Vehicles

6.  Solar Constant (Isc) or Extra-terrestrial Radiation: The
rate at which energy is received from the sun on a unit
area perpendicular to the rays of the sun on the outer
surface of the earth’s atmosphere.
 Isc = 1367 W/m2
 Isc varies due to earth’s varying distance (elliptical
path) from the sun

7. Spectral Distribution of Solar
Radiation

8.  Nuclear Fusion is the source of solar energy.
 Surface temperature of sun is 6000 K.
 Solar radiation is received on earth’s surface in an attenuated
form because it is subjected to the mechanisms of
absorption and scattering as it passes through the earth’s
atmosphere.
 Though solar constant is 1367 W/m2, earth receives
approximately 700-1000 W/m2 (subject to weather
conditions) due to attenuation by the earth’s atmosphere.

9.  Absorption: Due to Ozone, Water Vapour, CO2, CO, O2, CH4,
etc
 Scattering: Due to all gaseous molecules as well as
particulate matter in atmosphere
 Beam Radiation, Diffuse Radiation
 Global Radiation: The sum of Beam and Diffuse radiation
falling on a horizontal surface

10.  GHI (Global Horizontal Irradiance) for Flat Plate Collector e.g.
PV panel, solar water heater
 DNI (Direct Normal Irradiance) for Concentrated Solar Power
(CSP)

11. PV power plants CSP plants
Parameter Value Parameter Value
Minimum average annual GHI 5.00 kWh/m2
/day Minimum average annual DNI 5.00 kWh/m2
/day
Maximum ground slope 5% or 2.86⁰ Maximum ground slope 5% or 2.86⁰
Water availability minimal Water availability 500–1000 gallons per MWp of
panels per year or 2.9-3.5 m3
/MWh
Maximum distance from grid 40 km Maximum distance from grid 40 km
Minimum land availability 40 acres Minimum land availability 40 acres
Land requirement 5 acres/MWp Land requirement 10 acres/MWp
Site shouldn’t have restricted or
specially designated areas
Not applicable Site shouldn’t have restricted or
specially designated areas
Not applicable