Explain Solar PV system, types, environmental impacts, and solar cells. Know advantages and disadvantages.

1. Prepared By-
Mr.Premanand Desai LECTURER /EE
B.L.D.E. Association’s
Shree sanganabasava Maha swamiji Polytechnic,Vijayapur-03
Cell No:+917892881829
E-Mail-ID:premananddesai@gmail.com

2. Unit-III
SOLAR PHOTOVOLTAIC SYSTEM
Course outcome : 03 - Explain Solar PV system, types,
environmental impacts, and solar cells. Know advantages and
disadvantages.

3. Photovoltaic effect solar cell
• The "photovoltaic effect" is the basic physical process
through which a solar cell converts sunlight into electricity.
• In typical solar cell , a p-n junction is formed between two
types of semiconductor namely P- type and N-Type
semiconductors.
• When Sunlight strikes a photovoltaic cell, the electrons-
Hole pairs are formed. The electric field existing across P-N
junction causes the electron hole pairs to separate.
• As free electrons are generated, they can be collected via
an external circuit and flow from N-type to P-Type material.
thus the current flow takes place.

4. Solar power
 Solar power is the conversion of sunlight into
electricity, either directly using photovoltaics
(PV), or indirectly using concentrated solar
power (CSP).
 Concentrated solar power systems use lenses
or mirrors and tracking systems to focus a
large area of sunlight into a small beam.
 Photovoltaics convert light into an electric
current using the photovoltaic effect.

7. Construction of solar cell
The junction diode is made of Si or GaAs. A thin layer of p-type is
grown on the n-type semiconductor. Top of the p-layer is provided with a few
finer electrodes which leaves open space for the light to reach the thin p-
layer and it under lays p-n junction. Bottom of the n-layer is provided with a
current collecting electrode
Solar cell

8. Solar photovoltaic module
Solar PV module
Block diagram

9. Photovoltaic (PV) array
 To generate electrical power more than that of individual solar cell and solar module ,
number of solar modules are combined together to form any array which is called solar
array or photovoltaic array.
 The main feature of a solar array is that it is able to meet any electrical power requirement .
 Thus a solar array or PV array is an interconnected system of PV modules that function as a
single unit producing electricity in which solar modules are assembled as a discrete
structure with a single common mounting as shown in above figure.

10. Materials used in solar cells
• The materials which are used for this purpose must have band
gap close to 1.5ev. Commonly used materials are-
1. Crystalline silicon (c-Si): These cells are entirely based around
the concept of a p-n junction. Solar cells made of c-Si are made
from wafers between 160 and 240 micrometers thick.
2. Monocrystalline silicon (mono-Si): Solar panels using mono-Si
cells display a distinctive pattern of small white diamonds.
3. Epitaxial silicon : Solar cells made with this technique can have
efficiencies approaching those of wafer-cut cells, but at
appreciably lower cost.

11. 4. Polycrystalline silicon : Polysilicon cells are
the most common type used in photovoltaics
and are less expensive, but also less efficient,
than those made from monocrystalline silicon..
5.Cadmium telluride : Cadmium telluride is the
only thin film material so far to rival crystalline
silicon in cost/watt. However cadmium is highly
toxic and tellurium supplies are limited.
6.Gallium arsenide thin film : The semiconductor
material Gallium arsenide (GaAs) is also used for
single-crystalline thin film solar cells.

12. Applications of Solar cells / solar power plant:
1. In space programs for electric power
generation.
2. For navigational signals.
3. Highway emergency systems.
4. Rail road crossing signals.
5. Water pumping for irrigation purposes.
6. Street lighting.
7. Weather monitoring system

13. Classification of solar photovoltaic (PV)systems
1. Stand-alone solar PV system.
2. Grid interactive (connected) solar PV system.
3. Hybrid system.

14. 1. Stand-alone solar PV system.

15. • In the block diagram , it consists of PV array, charge
regulator, battery, inverter, D.C and A.C Load centers.
• The PV array converts solar energy into electrical energy.
The DC output of PV array is connected to the battery
through charge controller unit.
• The charge controller consists of blocking diode, when
there is no sun shine it prevents battery to discharge
through PV array.

16. • The battery gets charged using DC out put of the PV
array during day light hours.
• The battery output can be connected either to DC load
centers or AC load centers. When battery is connected
to AC load centers,
• The battery output is connected to an inverter. The
inverter converts DC into AC and then supplies power
to the AC load.

17. 2.Grid interactive (connected) solar PV system

19. • Grid-connected or utility-interactive PV systems are designed to operate in
parallel with interconnected with the electric utility grid.
• The primary component in grid-connected PV systems is the inverter, or
power conditioning unit (PCU).
• The PCU converts the DC power produced by the PV array into AC power
consistent with the voltage and power quality requirements of the utility
grid, and automatically stops supplying power to the grid when the utility
grid is not energized.

20. • A bi-directional interface is made between the PV
system AC output circuits and the electric utility
network, typically at an on-site distribution panel
or service entrance.
• This allows the AC power produced by the PV
system to either supply on-site electrical loads, or
to back feed the grid when the PV system output
is greater than the on-site load demand.
• At night and during other periods when the
electrical loads are greater than the PV system
output, the balance of power required by the
loads is received from the electric utility.

21. Advantages of PV systems
1. PV panels provide clean – green energy.
2. Solar energy is energy supplied by nature – it is
thus free and abundant.
3. Solar energy can be made available almost
anywhere there is sunlight
4. photoelectric phenomenon, produce electricity
in a direct electricity generation way
5. Operating and maintenance costs for PV panels
are considered to be low.

22. 6. PV panels have no mechanically moving parts.
7. Absence of moving parts.
8. Long life and highly reliable.
9. It Can be installed at load centers & saves cost
of transmission and distribution lines.
10. It can be easily started as no starting time is
required

23. Disadvantages of PV systems
1. solar energy has intermittency issues; not shining
at night but also during daytime there may be
cloudy or rainy weather.
2. Solar energy panels require additional
equipment (inverters) to DC to AC in order to be
used on the power network.
3. High capital investment.

24. 4. Solar panels efficiency levels are relatively low
(between 14%-25%) compared to other
renewable sources of energy.
5.Manufactures of solar array is labor intensive.

25. Environmental Impacts Of Solar PV System.
• Hazardous Materials
The PV cell manufacturing process includes a number of
hazardous materials, most of which are used to clean and purify
the semiconductor surface. These chemicals, similar to those used
in the general semiconductor industry, include hydrochloric acid,
sulfuric acid, nitric acid, hydrogen fluoride, trichloroethane, and
acetone. The amount and type of chemicals used depends on the
type of cell, the amount of cleaning that is needed, and the size of
silicon wafer.

26. • Life-Cycle Global Warming Emissions
While there are no global warming emissions associated with
generating electricity from solar energy, there are emissions
associated with other stages of the solar life-cycle, including
manufacturing, materials transportation, installation,
maintenance, and decommissioning and dismantlement. Most
estimates of life-cycle emissions for photovoltaic systems are
between 0.07 and 0.18 pounds of carbon dioxide equivalent
per kilowatt-hour.

27. • Ecological impacts: In the point of generating
electricity at a utility-scale, solar energy
facilities necessitate large area for collection of
energy. due to this, the facilities may interfere
with existing land uses and can impact the use
of areas such as wilderness or recreational
management areas. As energy system may land
through materials exploration, extraction,
manufacturing and disposal, energy footprints
can become incrementally high.

28. • Impacts to soil, water and air resources :
The construction of solar facilities on vast area
of land imposes clearing and grading , resulting in
soil compaction, alteration of drainage channels
and increased erosion.

29. MODEL QUESTIONS BANK
• Cognitive Level: UNDERSTAND
1. Explain Photovoltaic effect and solar power.
2. Explain the Construction of solar cell and solar photovoltaic module with
block diagram.
3. Explain Construction of photovoltaic panel.
4. state the Classification of solar photovoltaic systems.
5. List the Advantages and dis-advantages of PV systems.
• Cognitive Level: APPLICATION
1. Explain Construction of PV array.
2. Explain the Materials used for solar cells.
3. Explanation of stand-alone with block diagram
4. Explanation of grid interactive solar PV system with block diagram.
5. Explain the environmental effects of solar PV system.

30. Course outcome : 03
Explain Solar PV system, types, environmental impacts,
and solar cells. Know advantages and disadvantages.