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FINAL-REVIEW PROJECT PRESENTATION

DATE: 25th May 2015

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GUIDED BY: ANJU M (ASST PROF EEE DEPT)

Presented ByROHINI.SSANJUSH.SSUJINI.MVISHNU.M

AUTOMATIC SOLAR NIGHT LAMP

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ABSTRACT

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• 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.

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PROPOSED SYSTEM

BLOCK DIAGRAM&

CIRCUIT DIAGRAM

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Block Diagram

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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 In this circuit, it has been replaced by LED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.

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Circuit Diagram

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

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COMPONENTS USED

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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 )

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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.

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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

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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

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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.

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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.

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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.

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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.

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WORKING PRINCIPLE(CIRCUIT

EXPLANATION)

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• 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.

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• 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.

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ADVANTAGES

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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

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CONCLUSION

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

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FUTURE SCOPES&

APPLICATIONS

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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:

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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.

PHOTOVOLTAIC ARRAY

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• 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.

Solar Street light system with Automatic street light controller

A Future perspective

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Bed Rooms

Hostels and Hotels

Balcony / stair case / parking Lightings

Street lights

Garden Lights

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REFRENCE

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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

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THANK U…