1. FINAL-REVIEW PROJECT
PRESENTATION
DATE: 25th May 2015
1

2. GUIDED BY: ANJU M (ASST PROF EEE DEPT)
2
Presented By
ROHINI.S
SANJUSH.S
SUJINI.M
VISHNU.M

3. 3

4. • Here is a simple Solar Night lamp that turns on automatically
at sunset and stays on till morning. It uses 1 Watt High Bright
White LEDs to illuminate a confined area.
• Here the solar energy is converted into electrical energy with
the help of an solar panel and which is stored into an battery.
• Then from the battery LEDs are connected.
• Between LEDs and battery we are using an LDR and an
Transistor which act like an switch.
4

5. 5

6. Block Diagram
6

7. 7
Block Explanation
• Light dependent resistor: LDR senses the illumination
level and gives the input signal as voltage drop.
• Street light: Street light is the output of the circuit. In
this circuit, it has been replaced by LED
• ON OFF Control: The circuit is switched ON or OFF by
the transistor in saturation region or cut off region
respectively, which is controlled by the signal from LDR.
The collector current from the transistor toggle between
ON or OFF modes.

8. Circuit Diagram
8
The description of all the components used in this circuit is given
below.

9. 9

10. 1. SOLAR PANEL (6V)
2. RE-CHARGEBLE BATTERY (6V)
3. DIODE (IN4007)
4. CAPACITOR (470µF,25V)
5. POT (4.7K )
6. LDR
7. TRANSISTOR (SL1OO)
8. LED (1W, 4NOS)
9. RESISTOR (8.2Ω )
10

11. 1. SOLAR PANEL
 Solar panel refers either to a photovoltaic module, a solar hot
water panel, or to a set of solar photovoltaic (PV) modules
electrically connected and mounted on a supporting
structure.
 A PV module is a packaged, connected assembly of solar cells.
Solar panels can be used as a component of a
larger photovoltaic system to generate and
supply electricity in commercial and residential applications.
 Each module is rated by its DC output power under standard
test conditions (STC), and typically ranges from 100 to 320
watts.
11

12.  A single solar module can produce only a limited amount of
power; most installations contain multiple modules.
 A photovoltaic system typically includes a panel or an array of
solar modules, an inverter, and sometimes a battery and/or
solar tracker and interconnection wiring
12

13. 2. LDR-LIGHT DEPENDENT RESISTOR
 A photoresistor or light-dependent resistor (LDR) or photocell is
a light-controlled variable resistor.
 The resistance of a photoresistor decreases with increasing
incident light intensity; in other words, it
exhibits photoconductivity.
 A photoresistor can be applied in light-sensitive detector
circuits, and light- and dark-activated switching circuits
13

14.  A photoresistor is made of a high resistance semiconductor.
 In the dark, a photoresistor can have a resistance as high as a
few megaohms (MΩ), while in the light, a photoresistor can
have a resistance as low as a few hundred ohms.
 If incident light on a photoresistor exceeds a
certain frequency, photons absorbed by the semiconductor
give bound electrons enough energy to jump into
the conduction band.
14

15.  The resulting free electrons (and their hole partners)
conduct electricity, thereby lowering resistance.
 The resistance range and sensitivity of a photoresistor
can substantially differ among dissimilar devices.
 Moreover, unique photoresistors may react substantially
differently to photons within certain wavelength bands.
15

16. 3. DIODE
 A diode is a two-terminal electronic component that
conducts electric current in only one direction. A
semiconductor diode is a crystalline piece of semiconductor
material connected to two electrical terminals.
 The most common function of a diode is to allow an electric
current to pass in one direction while blocking current in the
opposite direction. Thus, the diode can be thought of as an
electronic version of a check valve. This unidirectional
behaviour is called rectification, and is used to convert
alternating current to direct current and to extract
modulation from radio signals in radio receivers.
16

17. 4. Light-emitting diodes
 Light-emitting diodes are elements for light signalization in
electronics. The basic principle behind the working of LED is
electroluminescence.
 The Light emitting diode should be forward biased to get the
light. In Light emitting diodes, electrons are injected from low
work function cathode to the conduction band of the n-type
semiconducting material and holes are injected from high
work function anode to the valence band ot the p-type
semiconducting material.
 When the electron in the conduction band combines with the
hole in the valence band, energy is released. In case of
indirect band gap semiconductors, photon will be released to
conserve of both energy and momentum. But in case of direct
band gap semiconductor, light will be emitted whose
wavelength depends on the band gap of the semiconductor.
17

18. 18

19. • Solar Panels positive and negative terminals can be directly
connected to the battery.
• Current from the Solar panel passes through IN 4007 diode
which acts as polarity protector.
• 470 uFcapacitor functions as a reservoir to give steady charge to
the battery in varying sunlight conditions.
• During varying sunlight condition the capacitor discharges and
supply charge to battery.
• Lamp circuit is an automatic switch controlled by an LDR During
day time LDR conducts taking the base voltage of the Driver
transistor SL 100 and it will be non conducting to keep the LEDs
off. 19

20. • At sunset, resistance of LDR increases and transistor conducts.
White LEDs get power and switches on.
• Alternately, 4.5 volt battery or mobile battery can be used.
• Backup time depends on the capacity of the battery since the
White LED takes 3 volts and 100-300 mA current.
20

21. 21

22.  Pollutant free
 Works according to the light intensity
 Low cost and reliable circuit
 Complete elimination of manpower
 System can be switched into manual mode whenever
required
22

23. 23

24. • Thus the working of the automatic SOLAR NIGHT LAMP was
explained in detail
24

25. 25

26. Application 1:
• The above circuit can be powered from a battery, which can
be charged during day time by harvesting the solar energy
through a solar cell as shown below:
26

27. Application 2:
• The solar energy harvested from sunlight can be stored,
inverted from DC voltage to AC voltage using sun tie
converter. The AC voltage can be stepped up and given to the
electric grid.
27
PHOTOVOLTAIC ARRAY

28. • The AC voltage from the electric grid can be stepped down,
rectified and used for powering the circuit. Meanwhile, the
street light can also be powered by the A.C. voltage, which is
controlled by a relay switch connected to the switching part of
the circuit. The above mentioned strategy will enable us to
harvest solar energy in an effective way for the operation of
the circuit and for powering the street light also.
28
Solar Street light system with
Automatic street light
controller
A Future perspective

29. Bed Rooms
Hostels and Hotels
Balcony / stair case / parking Lightings
Street lights
Garden Lights
29

30. 30

31. 1. Semiconductor Devices: Physics and Technology, S. M. Sze.,
New York: Wiley, 1985; 2nd ed., 2001, ISBN 0-471-33372-7.
2. Physics of Semiconductor Devices, S. M. Sze., New York:
Wiley, 1969, ISBN 0-471-84290-7 .
3. Solid State Physics, Hook, J. R.; H. E. Hall., Wiley, 2001,
ISBN 0-471-92805-4
31

32. THANK U…
32