Solar Photovoltaic (PV) Technology: Solar to Electricity

A solar
photovoltaic (SPV) technology is used to converts fraction of solar radiation
into electrical energy.
Solar
Photovoltaic (PV) Technology consist of:

A. Solar
cells:

Solar cells
is a p-n junction semiconductor device made of silicone which is generally used
to fabricate semiconductor chips of the computer and other electronic devices.
When sunlight hits the cells, the solar cell generates Direct Current (DC)
electric power. A silicon solar cell normally generates 0.6V DC and about 8A
Current depending on the area. Therefore, a solar cell of 6 inches can
generates power up to 5 watts at the present-day technology.
 

B. Solar
Photovoltaic (SPV) Module:

Solar
Photovoltaic (SPV) Module converts fraction of solar radiation into electrical
energy. SPV module is a single mono block unit having a fixed number of solar
cell strings (36, 72 etc.), which is the fundamental building block of SPV
systems. It consists of Solar cell strings sealed between the layers of Ethyl
Vinyl Acetate (EVA).
A SPV
module is made of specific number of solar cells generally connected in series.
The series and parallel combination of modules serve two purposes. The number
of modules connected in series generates the required voltage suitable to
supply power to the controller and the number of modules in parallel generates
the required current to drive the motor and pump.
A Solar PV
array consists of number of modules which are connected into series and
parallel configuration to provide required voltage and current to drive a
specific load(s).
SPV module
has two polarities positive (+) and negative (-) and when exposed to Sun,
generates Direct Current (DC) electricity. The current flows from positive (+)
to negative (-) terminals of the SPV Module, or SPV array. This electricity so
produced which is in the form of DC power, can either be used in this form
directly or converted into Alternating Current (AC). As we know, Alternating
Current (AC) is generally used for domestic purposes.
 

Also Read: International Solar Alliance

C. Solar PV
Array:

A
photovoltaic (PV) array is the complete power generating unit consisting of SPV
module. Solar PV array consists of parallel and series combination of identical
photovoltaic (PV) 9 modules to generate the required power (kWp) to operate any
electrical appliance/ equipment. Since this programme is on solar PV water
pumping system, electric appliance in this case implies to the solar water pump
and its connected motor.
 

D. Types of
PV Modules:

Three major
technology types of modules used in solar PV applications. The technology is
classified based on its manufacturing technology such as wafer based or thin
films, and the type of semiconductor material such as Si (silicon), A-Si
(arsenic silicon), Cd-Te (cadmium-telluride) and CIGS (copper, indium, gallium,
selenide).
 

Depending
on current or voltage requirement, solar modules are connected in two ways:

(a) Series
Connection of Solar Modules:

Three solar modules (37 volts/8 amps each) are connected in series.
In this connection voltages add up as given below:
37+37+37=111
volts (approximately)
It must be
noted for either series connection or in a parallel connection the type,
capacity, make etc. of solar modules should be IDENTICAL to enable the system
to function properly.
 

(b)
Parallel Connection of Solar Modules:

In parallel
connection of solar modules, the voltage output would remain then same but the
current would add up and increase as shown in the figure 2.8.
This
connection is employed where the high currents are required.
Three solar
modules (37V/ 8A each) are connected in parallel. The negative of the first
solar module is connected to the negative of the next solar module, and the
following panels follow suit. The terminals at the end comprise of the positive
terminals of all modules and the negative 11 terminals of all the modules. In
this connection current add up and voltage remains the same.
8+8+8=24
Amps

Advantages
of Solar PV Technology:

Major
Advantages of SPV Technology are as follows:

• Clean energy source
• Since it uses sunlight as input, no fuel cost incurred.
• As long as solar radiation is available the power to drive
  the motor & pump will available.
• Since it is standalone system its operation is not affected
  or disturb by other loads operating nearby unlike grid-based pumping system.
• The modularity makes it easy for being constructed in sizes
  as required.
• Ease of installation and transportation.
• Minimal maintenance required and has long life span (more
  than 25 years).
• Long operation life and no
  wear and tear as there are no moving parts.

 

Limitations:

The
major limitation of solar PV technology is the capex (capital expense) cost is apparently high. The power available could be intermittent and affected by moment
of the cloud. Without storage, it is not possible to use the solar pumps

in night time.
 

Applications Solar PV
Technology:

Power
Supply: Power
supply for household use, industrial and agricultural use, etc.
 
Residential:
Indoor
and outdoor lighting system, electrical equipment, electric gate opener,
security system, ventilator, water pump, water filter, emergency light, etc.
 
Lighting
System: Traffic
signalling system, telephone booth lighting, billboard lighting, parking lot
lighting, street lighting, lighting in remote areas etc.
 
Water
supply: Irrigation,
drinking water, livestock watering, agriculture, gardening and farming, mining,
public utility etc.
 
Battery
charging system: Emergency
power system, battery charging centres etc.
 
Agriculture:
Water
pumping, agricultural products fumigator, thrashing machines, water sprayer,
insect trap lighting etc.
 
Fishing:
Water
pumping, oxygen filling system for fish-farming etc.
 
Health
center: Refrigerator
and cool box for keeping medicines and vaccines, medical equipment, etc.
 
Communication:
Air
navigational aid, air warning light, lighthouse, beacon navigation aid,
illuminated road signage, railway crossing signals, emergency telephone etc.
 
Telecommunication:
Microwave
repeater station, telecommunication equipment,
portable
communication equipment (e.g. communication radio for service and military
exercise), weather monitoring station, etc.
 
Remote
area: Power
supply in remote areas like hill, island, forest and remote area where the
utility grids are not available, solar water purification, wild life fencing.
 
Space:
Satellite,
international space station, spacecraft, etc.
 
Energy
Parks: The
large mega scale power plants feeding power to ultrahigh voltage grids.
 
Rooftop:
Solar
PV systems installed on the roof of house, industries, govt buildings, large
industrials roofs etc. feed power to HT and LT grids.