Solar Charge Inverter - Electronics for you.

8/13/2019 Solar Charge Inverter - Electronics for you.

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1.2 Basic Principle of Inverter:Inverter is a device which converts the DC supply to AC supply. Let us see how itgenerates AC supply from DC supply.

Figure 1.2. Basic Principle of InverterIn this circuit DC input from battery is given to an inverter ckt and then its acoutput to a transformer. When the switch is closed the current starts to rise in theckt. This will make the transformer to generate an EMF, opposing the EMF of thebattery. If we assume that the resistance of the transformer is negligible, then thecurrent will rise at a constant rate. This rise will depend on the inductance of thetransformer; the more time will be needed, to produce the required current tobalance the EMF of the battery.Now if switch is opened before the current in the transformer grows fully, thecurrent in circuit will start to fall. This will make the transformer to generatereverse EMF. Now, once the ckt current reaches zero, the switch is once againclosed and this whole process will start to repeat itself. So, by producing open,close cycle of switch in this circuit, we can produce ac current o/p from a dc currentsource i.e. battery. The o/p from secondary winding of transformer will be a squarewave of frequency at which switch is opened and closed; this is the basic working

principle of inverter.

1.3 Classification of Inverter:Inverter can be classified on the basis of nature of source, nature of outputwaveform, type of commutation circuit used, configuration and type of powersemiconductor devices used. 1. Based on nature of input source:a) Voltage source inverter: In this input to the inverter is DC voltage.


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b) Current source inverters: In this voltage is converted into current source andthen applied to inverter as i/p.2. Based on type of commutation ckt used:a) Auxiliary

b) Complementary.3. Based on power semiconductor devices used:a) Thyristorizedb) Transistorizedc) MOSFET basedd) IGBT based4. Based on configuration of inverter:a) Seriesb) Parallelc) Bridge5. Based on nature of output waveform:a) Squareb) Quasi-Squarec) PWM wave.d) Sine wave.

2. LITERATURE SURVEY

2.1 Relevance:The greatest need of to days world is energy, which may be in any form. But theform of energy that is required the most is the electrical energy. The electricalenergy is non-renewable source of energy, so the need of the hour is to find out theways to utilize the available electrical energy carefully and to optimally use therenewable resources of energy which are present in abundance in the environment.The inverter is an electronic device, which provides the electrical energy that isstored in a battery. Today inverter is an essential commodity to provide an

uninterrupted power supply for the houses, offices, schools, hospitals etc. With ourproject we are trying to interface the inverter with user and sun so that the usercan make an optimum use of solar energy. We will do this by making the inverterprogrammable for the user so that he can get his required performance from theinverter and by attaching a battery with solar charger which in turn will save energyas well as money.


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2.2 Present Theories:The inverter is basically a DC to AC converter, which converts DC energy stored inbattery in AC energy for everyday requirement and provides uninterrupted powersupply. The inverters available in the market are of different range, specifications

and cost. The inverters are available in different output waveforms which are,1) Square wave inverters.2) Quasi-square wave inverters.3) PWM inverters.4) Sine wave inverters.There are inverters available which control the output voltage by the use of PWMpulse, these inverters use IC 3525 to produce PWM wave. These inverters uses theleds to indicate ON/Off condition of inverter. Hence, we can say, according to our survey we found that inverter is the mostessential and important device in the field of electronics development. Keeping thisin mind we are making an inverter which not only provides a continuous powersupply but also saves the tremendous of non-renewable resources of energy byusing solar energy.2.3 Proposed Work:Inverters which are available in the market are just passive product i.e. you have touse them only in one way. The concept of our project is to make these widely useddevices active and user friendly by making them flexible in their use. We canprogram the inverter as we like with the help of microcontroller used in it. Themicrocontroller is also used to produce PWM wave instead of using IC 3525. Also we

are charging the battery by means of the solar energy which not only saves themoney but also saves the tremendous of non-renewable resources of energy i.e.electrical energy.The programmable inverter is unique in following ways,1) Programmable output wattage and display.2) Programmable charging current and display.3) User interface using remote control.4) LCD display.5) Battery state display.

6) Backup time display.7) Extendable output wattage by the use of dual battery.8) Input voltage and frequency display.9) Required text display.10) Battery charging takes place by means of solar energy.

3. BLOCK DIAGRAM


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3.1 Block Diagram of Programmable Inverter:

Figure3.1: -Block Diagram of Programmable Inverter

3.2 Block Diagram of Solar Battery Charger:

Figure 3.2:- Block Diagram of SolarBattery Charger

3.3 BLOCK DIAGRAM DISCRIPTION:1. Microcontroller 89C52: -The AT89C52 is a low-power, high-performance CMOS 8-bit microcontroller with 8Kbytes of in-system programmable Flash memory. The device is manufactured usingAtmels high -density nonvolatile memory technology and is compatible with the

industry standard 80C51 instruction set and pin out.Memory to be reprogrammed in-system or by a conventional nonvolatile memoryprogrammer. By combining a versatile 8-bit CPU with in-system programmableFlash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller whichprovides a Highly-flexible and cost-effective solution too many embedded controlapplications.The AT89C52 provides the following standard features: 8K bytes of Flash, 256


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bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bittimer/counters, a six-vector two-level interrupt architecture, a full duplex serialport, on-chip oscillator and clock circuitry. In addition, the AT89S52 is designedwith static logic for operation down to zero frequency and supports two software

selectable power saving modes.The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port,and Interrupt system to continue functioning. The Power-down mode saves theRAM contents but freezes the oscillator, disabling all other chip functions until thenext interrupt or hardware reset.

Features of this microcontroller are : Compatible with MCS-51 Products

8K Bytes of In-System Programmable (ISP) Flash Memory 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz Low-power Idle and Power-down Modes 256 x 8-bit Internal RAM 32 Programmable I/O Lines Three 16-bit Timer/Counters

Microcontroller is used as the controlling device of the system. It is connected withthe LCD Display, Remote, Pre amplifier, EEPROM, Triac and Triac driver circuits,Multiplexer, changeover relay. Microcontroller will generate the PWM pulse with 50Hz frequency. O/P of microcontroller is given to the pre amplifier.

2. PIC16F877A Microcontroller:-Core features: High -performance RISC CPU Only 35 single word inst ructions to learn

All single cycle instructions except for program branches which are two cycle Operating speed: DC - 20 MHz clock input DC - 200 ns instruction cycle Up to 8K x 14 words of FLASH Program Memory, Up to 368 x 8 bytes of Data Memory (RAM)Up to 256 x 8 bytes of EEPROM data memory Pinout compatible to the PIC16C73B/74B/76/77 Interrupt capability (up to 14 sources)


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Eight level deep hardware stack Direct, indirect and relative addressing modes Power -on Reset (POR) Power -up Timer (PWRT) and Oscillator Start-up Timer (OST)

Watchdog Timer (WDT) with its own on -chip RC oscillator for reliable operation Programmable code -protection Power saving SLEEP mode Selectable oscillator options Low -power, high-speed CMOS FLASH/EEPROM technology Fully static design In -Circuit Serial Programming (ICSP) via two pins Single 5V In -Circuit Serial Programming capability In -Circuit Debugging via two pins Processor read/write access to program memory Wide operating voltage range: 2. 0V to 5.5V High Sink/Source Current: 25 mA Commercial and Industrial temperature ranges Low -power consumption:-

Peripheral Features:

Timer0: 8 -bit timer/counter with 8-bit prescaler

Timer1: 16 -bit timer/counter with prescaler, can be incremented during sleep viaexternal crystal/clock

Timer2: 8 -bit timer/counter with 8-bit period register, prescaler and postscaler

Two Capture, Compare, PWM modules

- Capture is 16-bit, max. resolution is 12.5 ns


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- Compare is 16-bit, max. resolution is 200 ns

- PWM max. resolution is 10-bit

10 -bit multi-channel Analog-to-Digital converter

Synchronous Serial Port (SSP) with SPI (Master Mode) and I2C (Master/Slave)

Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI) with 9 -bit address detection.

Parallel Slave Port (PSP) 8 -bits wide, with external RD, WR and CS controls(40/44-pin only)

Brown -out detection circuitry for Brown-out Reset (BOR)

3. Pre Amplifier: -

1. It is designed by using the transistors

2. We will use transistor BC 547 for designing the pre amplifier.

3. Pre amplifier is used to amplify o/p, which is present at the micro controller o/p

terminals.

4. By using the pre amplifier we are converting the 5v s/g to 12v which is requiredto drive the power MOSFETs.

5. The pre-Amplifier converts the microamperes current from m/c to ma.


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4. Power Amplifier :-

1. Power amplifier is designed by using the power MOSFETs.

2. The MOSFETs used are IRF3205 and are connected in push pull configuration.

3. Power amplifiers are used to improve the power handling capability of ckt.

4. Power Amplifiers will convert the current in ma to the current in severalamperes.

5. Voltage Booster:-

1. Voltage booster is consisting of the transformer it will act as step up or stepdown on the basis of the operation mode of inverter.

2. At the o/p of step up transformer we get the 230v ac o/p.

3. Voltage booster will get the i/p from the power amplifiers.

Transformer: -

A transformer is a device which works on principle of mutual induction.


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Transformers are available in two types step up transformer and step downtransformer.

Step up transformer is used to increase the secondary (output) voltage inproportion to primary (input) voltage.

Step down transformer is used to decrease the secondary (output) voltage inproportion to primary (input) voltage.

The transformer is rated in volt-amperes rather than in watts.

Advantages of transformer : -

1. The output can be varied proportional to the input.

2. Noiseless transfer of power from primary to secondary, as there is no mechanicalparts involved.

3. As there is no electrical contact between the primary and secondary of thetransformer, circuit connected to the secondary is safe from the electric shock

Parts of a transformer

Coil: - In a transformer, coil is one of the most important part and we require wireto make the coil.


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5) Selective erasing is not possible. All the locations get erased.

6) Time required for erasing is long 10 to 15 min.

7) It is necessary to remove the PROM.

8) EPROM is less expensive.

9) It is an UV erasable & electrically programmable EPROM, a transparent lid isprovided in the package.

7. Relay:-

An electromagnetic relay is basically a s/w operated by magnetic force. Thismagnetic force is generated by flow of current through a coil in a relay .The relayopens or closes a ckt when current through a coil is started or stopped. The Relaywhich we have used is OEN-58-06-2C.

8. TRIAC And TRIAC Driver :-

We are using the BT139 as Triac and MOC 3021 as a Triac driver. Triac is basicallyused to control the charging current by controlling the 230V AC voltage bycontrolling the phase angle of triac. We control the 230V AC supply by giving

appropriate gate pulses to it. When the mains AC supply fails the m/c detects it andstart controlling the gate pulses given to triac using triac driver. It is the 6 pin IC.

It is used as the TRIAC driver.


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9. LCD Display:-

The LCD is used to display the information or users datab ase, entering amount.The LCD panel's Enable and Register Select is connected to the Control Port. TheControl Port is an open collector / open drain output. While most Parallel Ports haveinternal pull-up resistors, there are a few which don't. Therefore by incorporatingthe two 10K external pull up resistors, the circuit is more portable for a wider rangeof computers, some of which may have no internal pull up resistors. We make noeffort to place the Data bus into reverse direction. Therefore we hard wire the R/Wline of the LCD panel, into write mode. This will cause no bus conflicts on the datalines. As a result we cannot read back the LCD's internal Busy Flag which tells us if

the LCD has accepted and finished processing the last instruction. This problem isovercome by inserting known delays into our program. The 10k Potentiometercontrols the contrast of the LCD panel. Nothing fancy here. As with all theexamples, I've left the power supply out. You can use a bench power supply set to5v or use a onboard +5 regulator. Remember a few de-coupling capacitors,especially if you have trouble with the circuit working properly.

LCD Module : In recent years the LCD is finding widespread use replacing LEDs(Seven Segment LEDs or other multistage LEDs). This is due to the followingreasons: The declining prices of LCDs. The ability to display numbers, charactersand graphics. This is in contrast to LEDs, which are limited to numbers and a fewcharacters. Incorporation of a refreshing controller into the LCD, thereby relievingthe CPU of the task of refreshing the LCD. In contrast, the LED must be refreshedby the CPU (or in some other way) to keep displaying the data.


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The constructional diagram of LCD Module is as shown

Figure : Constructional Diagram of LCD Module

Reflective twisted pneumatic liquid crystal display.1.Vertical filter film to polarize the light as it enters.2.Glass substrate with ITO electrodes. The shapes of these electrodes willdetermine the dark shapes that will appear when the LCD is turned on or off.Vertical ridges etched on the surface are smooth.3.Twisted pneumatic liquid crystals.4.Glass substrate with common electrode film (ITO) with horizontal ridges to line upwith the horizontal filter.5.Reflective surface to send light back to viewer. (In a backlit LCD, this layer isreplaced with a light source.)

VCC, VSS and VEE:When VCC and VSS provide +5V and ground respectively, VEE is used forcontrolling LCD contrast.RS (Register Select):

There are two very important registers inside the LCD. The RS pin is used for theirselection as follows. If RS = 0, the instruction command code register is selected,allowing the user to send a command such as clear display, cursor at home, etc. IfRS = 1 the data register is selected, allowing the user to send data to be displayedon the LCD.R/W (Read/Write):R/W input allows the user to write information to the LCD or read information from


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4.2 Circuit Diagram of Solar charging kit:

4.3 Circuit Diagram Description:

As seen from the circuit diagram different resistors, capacitors, inductors ICs . We


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have used the microcontroller IC89s52,multiplexer CD4051,EEPROM24c02,PC817,Triac Driver MOC3021,Triac BT139,Transformer,Regulator IC 7805, 7812,op-amp LM324 ,LM393 ,transistors Bc547,Bc557, diodes 1N4148,1N4007,BA159Pin no. 1 of micro controller is connected to the preamplifier circuitry .the

preamplifier circuitry is three stage amplifier. The amplifier is connected in CEconfiguration. We have use the BC547 for designing the preamplifier.Pin no.3 is also connected to the second preamplifier circuitry which is also designby using BC547 the output of these two preamplifier circuitry are connected topower amplifier stage. This stage is design by power MOSFET we have usedIRF3205 for designing the power amplifier this power amplifier is designed in push-pull configuration the out of these push-pull amplifier stage is given to 12-0-12winding of transformer. The two diode(1N4007) at the power amplifier stage areused to avoid damaged due to reverse voltage of 12V.Pin no.4 ,5 & 6 of microcontroller is connected to the EEPROM IC24C04 which is 8terminal IC. Microcontroller will read this memory at time each run. This memorywill store the values which are changed by the user.Pin no 7 & 8 are open.

Pin no-9 is reset pin of microcontroller and it is connected to the reset circuit.Pin no-10 is connected to the buzzer circuit, which consists of transistor & buzzer,which will work when mains supply is absent.Pin no-11 is connected to the relay circuit it consists of transistor BC547,relay

switch used is 58-06-2C. two diodes at this stage are used to avoid the relaychattring.this relay circuit is of two stage.

Pin no-12 is connected to interrupt circuit which is designed by using BC547.

Pin no-13 is connected to remote sensorPin no-15 is connected to third driver circuit this third circuit comes into actionwhen there is inductive load it consist of transistor which is connected in common

emitter configuration output of this stage is given to two power MOSFET IRFP250through 470 ohm resistances .output of these MOSFET is given to 50V winding oftransformer.Pin no-16 of micro controller is connected to MOC3021 output of 3021 is connectedto Triac circuitry. Triac is used to control charging current. Pin no-17 is given toPC817 which is used for fuse blow indicationPin no-18 &19 are XTAL1 &XTAL2 of microcontroller these pins are connected to


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oscillator circuit .this oscillator circuit will generate the clock to synchronize all theinternal operation of microcontroller. We have used 24MHz crystal oscillatorcapacitors c1 &c2 are used to stabilize the n/wPin no-21 27are connected to LCD display Pin no-21-D4,22-D5,23-D6,24-D7,25-

enable,26-RS and 27-switch..

Pin no-22-24 are also connected to Pin no-9,10,11 of CD4051 which will act asmultiplexer lines of CD4051. CD4051 has diff. Input from main supply voltage,inverter voltage through bridge rectifier and op-amp circuit . we have used LM324for our purpose CD4051 is also connected with inverter current circuit and chargingcurrent circuit also battery voltage is given to CD4051 input terminal .

Pin no-3 is output pin of CD4051 which is connected to microcontroller Pin no-28through op-amp.

Pin no-29-36 are open,pin-no28,37,38 are connected to op-amp393.pin no-40 isVcc of microcotroller.

TRANSFORMER:-It is a 150w, 10-0-10 V transformer. The transformer is working as step down incharging mode and step up in the inverter mode. In charging mode the transformer

not only steps down the voltage to safe value but also isolates the low powerelectronic circuitry from high power mains and it also charges the battery in thismode. During step up operation it is provided with the pulses from themicrocontroller.

REGULATOR:-There are various types of voltage regulator but we choose 7805 regulators due totheir simplicity.

These are the reasons why regulators are used (why simple power supply does notprovide constant output voltage):- Output voltage varies with ac input. Output voltage changes with functions in dc load current. Output voltage varies with time temperature particularly if semiconductor devicesare used.Three terminal voltage regulator in which the fixed output voltage is available at


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In this Inverter, charging current, o/p wattage, is controlled or changed accordingto user requirement within the battery limit by using the microcontroller.Microcontroller has I/p as inverter vtg, mains vtg, charging c/n, inverter c/nthrough the op-amp. M/C is connected with LCD display, EEPROM, relay, remote,

Triac and Triac driver ckt, pre amplifier, mux.Inverter can basically operate in three different modes as:-A) Inverter Mode:-In the inverter mode of operation inverter can operate as follows,Mux has different i/p from the inverter o/p, battery vtg, mains vtg., charging c/n,inverter c/n it is given to the mux through the op-amp 741. M/C will select the i/pdepending on its requirements. M/c will generate a 50 Hz PWM pulse which is givento pre-amplifier where it is get amplified then its o/p is given to power amplifier.O/p of power amplifier is given to voltage booster, which is basically a step uptransformer. O/p of step up transformer is ac o/p 230V.EEPROM stores theparameters of inverter which are entered by user according to his requirement.When AC mains supply fails then relay switches to battery and Inverter will operatein Inverter mode & when it is connected to mains vtg it is in charging mode andbattery is in charging condition. We can change the charging C/N, o/p wattage, o/pvoltage as per the requirement & this can be achieved by using remote control thatis connected to micro controller. So, we can say our Inverter is programmableInverter. LCD display is used which displays charging C/N, O/P voltage, back upvoltage battery voltage.

B) Charging Mode:-

System Operates in Charging Mode when either the AC mains supply or the solarenergy or both are available.When mains is available:1. The M/c detects that AC mains supply is available and it gives the signals to triacdriver which controls the gate pulses given to triac. Due to the gate pulses theOutput vtg of triac is controlled which in turn controls the charging current given tothe battery. The o/p of triac is connected to the transformer which is operated as

step-down transformer and it gives 12V and required charging current at thesecondary which charges to battery.When the solar energy is available:2. The panel o/p is given to the battery with a diode connected in between thepositive terminals of the panel and the battery. Because of this the feedback frombattery to the solar charging kit will not be there as the diode will be in reversebiased mode.


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C) Programming Mode:-

In this Mode the System is programmed according to the users requirement with

the help of IR Remote.In this mode we can program1) Output voltage.2) Output Current.3) Charging Current.4) Text Display.

The values of above Parameters given by user are stored in EEPROM. Whenmicrocontroller wants this value then it will read this from the EEPROM.

5.1 Battery Charging in Inverter:In an inverter when the mains ac available the mains supply is connected to 0-230vtaping of inverter transformer through a relay .In this situation transformer worksas a step down transformer, which has 0-140v taping at the primary and 12-0-12vat secondary. This voltage at secondary is used to charge the battery connected tothe inverter when the mains ac supply fails the relay makes 12-0-12v tapingprimary and 0-230v taping secondary this makes the inverter to provide 230v acsupply from the 12v battery so when single transformer is used for inverter andcharger operation then the transformer is act as step up transformer and step down

transformer for inverter and charging mode resp..One of the most part of inverter is battery. It is the source of power when mainssupply fails. Proper working of inverter dependence on conditions and capabilities ofbattery being used.There are two categories of battery:a) Primary Battery:-Primary batteries are for single use as the chemical reaction that produces electriccurrent in them are irreversible these are chip and simple to use.E.g. Zinc carbon battery, zinc manganese alkaline battery.

b) Secondary Battery:-Secondary battery are rechargeable battery the can use multiple times. Thesebatteries can be use in industries and automobiles where higher initial current isrequired.E.g. nickel cadmium, lead acid batteryBackup time provided by inverter mainly depends on rating of battery use withthem. Voltage rating and ampere hr rating is used to define power availability or


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capacity of battery .The backup time provided by battery connected to inverterdepends on the dc bus voltage of inverter. Life of battery is depend on chargingmethod use to charge the battery Three types of charging circuits are used ininverter to charge the battery, Constant voltage, constant current, constant voltage

constant current.

Storing Solar Energy in Batteries:

The most common method of storing solar electricity is to use it to charge batteries.Building a solar-powered battery charger is an inherently safe activity because ofthe way solar cells self-limit the amount of current they produce. Recharging abattery at too fast a rate (too high a current) might cause a buildup of gas insidethe battery, potentially causing it to explode. Charging batteries with mini solar

panels eliminates this potential safety hazard. The voltage of a power sourceindicates its ability to force electrons through an electrical circuit. When a battery isconnected to a circuit, it forces electrons out of its negative terminal (marked witha minus [-] sign), through the circuit, and into its positive terminal (marked with aplus [+] sign). This action slowly changes the chemical makeup of the battery.With use, this change reduces the voltage of the battery and at some point thebattery can no longer force the electrons through the circuit. At this point we saythe battery is dead. For some dead batteries, another power source can be used to force the electrons

to flow in the opposite direction and cause the chemical makeup of the battery toreturn to its original state. The battery is then recharged. In order to do this, thevoltage of the other power source must be greater than the charged voltage of thebattery.

Lead-Acid Battery Operation:-Lead-Acid Battery Charging :Lead-acid battery chargers attempt to force constant voltage Bulk charge - At max. current, battery voltage is below set point

_ Battery voltage increases as the battery charges Once the battery recovers sufficient charge, voltage is controlled

_ May be 2 stage charge - bulk & constant voltage (14.0V) _ May be 3 stage charge - bulk, acceptance (14.3V) & float (13.3V) _ May offer equalization (15.3V) mode for periodic battery conditioning

Solar Panel:


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Determine your solar charging goals and estimated power use Continuous dry camping

_ Refill at least what you use each day _ Can require a large solar system, perhaps 150 - 300W or more

Long weekend dry camping _ Refill a portion of what you use each day _ If you can last 3 days on 200 amp- hours, one 75W panel can extend this to 5days, or two 75W panels to 12 days Storage maintenance

_ 50W is usually sufficient

Solar Charging System :A solar charging system consists of one or more solar panels and a charge

controller. Charge controller prevents overcharging the battery May display battery voltage and/or charge current

The Photo Voltaic Module Charger Controller:There are three types available1. On/Off (bang-bang) type controller

_ Disconnects module when high battery voltage is reached ( 14V) _ Reconnects module when battery voltage lowers ( 13V)

_ Control may be relay or solid state2. Pulse Width Modulation (PWM)

_ When desired battery voltage is reached ( 14 V) output turns on/offquite rapidly (100Hz - 50KHz)

_ Battery voltage held constant, producing a more fully charged battery3. Maximum Power Point Tracking (MPPT)

_ Provides PWM type battery voltage control _ Extracts all available power from the PV module _ Patent Pending Solar Boost TM MPPT technology can increases chargecurrent up to 30% or more compared to traditional charge controllers

Photovoltaic Electricity :Photovoltaic (PV) is the field of technology and research related to the applicationof solar cells for energy by converting sunlight directly into electricity . Due to thegrowing need for solar energy , the manufacture of solar cells and photovoltaicarrays has expanded dramatically in recent years
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The bottom layer is doped with a P type material such as Aluminum, Gallium orIndium to produce holes (the green circles). The N type layer is doped withPhosphorous, Arsenic or Antimony to create mobile electrons (the blue dots). Thefigure has two phases. The dark phase in which no light is necessary and the light

phase in which light is necessary.DARK PHASE: Initially no charge difference exists between the barrier junction.However because of the crystalline nature of Silicon electrons unbounded by astable octet in the N layer have a tendency to migrate across the junction barrier toform a stable octet in the P layer. When this happens a difference in potential is setup between the two layers.LIGHT PHASE: Electrons become excited when light quanta penetrates into the Player. The excited electrons have two choices of movement. They may migratethrough the external circuit or short circuit there way across the barrier junction. Ifthe photoelectric circuit is constructed correctly they will find their way back to theN junction through the external circuit.

Photo generation of charge carriers:When a photon hits a piece of silicon, one of three things can happen:1. The photon can pass straight through the silicon this (generally) happens forlower energy photons,2. The photon can reflect off the surface,3. The photon can be absorbed by the silicon, if the photon energy is higher thanthe silicon band gap value. This generates an electron-hole pair and sometimes

heat, depending on the band structure.

When a photon is absorbed, its energy is given to an electron in the crystal lattice.Usually this electron is in the valence band , and is tightly bound in covalent bondsbetween neighboring atoms, and hence unable to move far. The energy given to itby the photon "excites" it into the conduction band , where it is free to move aroundwithin the semiconductor.The covalent bond that the electron was previously a part of now has one fewerelectron this is known as a hole. The presence of a missing covalent bond allowsthe bonded electrons of neighboring atoms to move into the "hole," leaving anotherhole behind, and in this way a hole can move through the lattice. Thus, it can besaid that photons absorbed in the semiconductor create mobile electron-hole pairs.A photon need only have greater energy than that of the band gap in order toexcite an electron from the valence band into the conduction band. However, thesolar frequency spectrum approximates a black body spectrum at ~6000 K, and as
http://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Band_gaphttp://en.wikipedia.org/wiki/Band_gaphttp://en.wikipedia.org/wiki/Band_gaphttp://en.wikipedia.org/wiki/Valence_bandhttp://en.wikipedia.org/wiki/Valence_bandhttp://en.wikipedia.org/wiki/Valence_bandhttp://en.wikipedia.org/wiki/Conduction_bandhttp://en.wikipedia.org/wiki/Conduction_bandhttp://en.wikipedia.org/wiki/Conduction_bandhttp://en.wikipedia.org/wiki/Frequency_spectrumhttp://en.wikipedia.org/wiki/Frequency_spectrumhttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Frequency_spectrumhttp://en.wikipedia.org/wiki/Conduction_bandhttp://en.wikipedia.org/wiki/Valence_bandhttp://en.wikipedia.org/wiki/Band_gaphttp://en.wikipedia.org/wiki/Photon


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such, much of the solar radiation reaching the Earth is composed of photons withenergies greater than the band gap of silicon. These higher energy photons will beabsorbed by the solar cell, but the difference in energy between these photons andthe silicon band gap is converted into heat (via lattice vibrations called phonons )

rather than into usable electrical energy.

Charge carrier separationThere are two main modes for charge carrier separation in a solar cell:1. Drift of carriers, driven by an electrostatic field established across the device2. Diffusion of carriers from zones of high carrier concentration to zones of lowcarrier concentration (following a gradient of electrochemical potential).In the widely used p-n junction solar cells, the dominant mode of charge carrierseparation is by drift. However, in non-p-n-junction solar cells (typical of the third

generation of solar cell research such as dye and polymer thin-film solar cells), ageneral electrostatic field has been confirmed to be absent, and the dominant modeof separation is via charge carrier diffusion.

The p-n junction (Semiconductor):The most commonly known solar cell is configured as a large-area p-n

junction made from silicon. As a simplification, one can imagine bringing a layer ofn-type silicon into direct contact with a layer of p-type silicon. In practice, p-n

junctions of silicon solar cells are not made in this way, but rather, by diffusing ann-type dopant into one side of a p-type wafer (or vice versa).If a piece of p-typesilicon is placed in intimate contact with a piece of n-type silicon, then a diffusion ofelectrons occurs from the region of high electron concentration (the n-type side ofthe junction) into the region of low electron concentration (p-type side of the

junction). When the electrons diffuse across the p-n junction, they recombine withholes on the p-type side. The diffusion of carriers does not happen indefinitelyhowever, because of an electric field which is created by the imbalance of chargeimmediately on either side of the junction which this diffusion creates. The electricfield established across the p-n junction creates a diode that promotes current to

flow in only one direction across the junction. Electrons may pass from the n-typeside into the p-type side, and holes may pass from the p-type side to the n-typeside, but not the other way around.This region where electrons have diffused across the junction is called the depletionregion because it no longer contains any mobile charge carriers. It is also known asthe "space charge region".
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Connection to an external load:Ohmic metal - semiconductor contacts are made to both the n-type and p-type sidesof the solar cell, and the electrodes connected to an external load. Electrons thatare created on the n-type side, or have been "collected" by the junction and swept

onto the n-type side, may travel through the wire, power the load, and continuethrough the wire until they reach the p-type semiconductor-metal contact.Here, they recombine with a hole that was either created as an electron-hole pairon the p-type side of the solar cell, or are swept across the junction from the n-type side after being created there.

To understand the electronic behavior of a solar cell, it is useful to createa model which is electrically equivalent, and is based on discrete electricalcomponents whose behavior is well known. An ideal solar cell may be modeled by acurrent source in parallel with a diode ; in practice no solar cell is ideal, so a shuntresistance and a series resistance component are added to the model. The resultingequivalent circuit of a solar cell is shown on the left. Also shown on the right, is theschematic representation of a solar cell for use in circuit diagrams.

Disadvantages:1. Cost may not cover lifespan savings unless a preferential feed-in tariff is offeredby the grid network. But this depends on location and energy prices.2. Solar electricity is often initially more expensive than electricity generated byother sources.

3. Solar electricity is not available at night and is less available in cloudy weatherconditions. Therefore, a storage or complementary power system is required.4. Limited power density: Average daily insulation in the contiguous U.S. is 3-7kWh/m and on average lower in Europe.5. Solar cells produce DC which must be converted to AC (using a grid tie inverter ) when used in currently existing distribution grids. This incurs an energy loss of 4-12%.

Advantages:1. The 89 pet watts of sunlight reaching the earth's surface is plentiful - almost6,000 times more than the 15 terawatts of average power consumed by humans.Additionally, solar electric generation has the highest power density (global mean of170 W/m) among renewable energies. Solar power is pollution free during use.Production end wastes and emissions are manageable using existing pollutioncontrols. End-of-use recycling technologies are under development.
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2. Facilities can operate with little maintenance or intervention after initial setup.3. Solar electric generation is economically superior where grid connection or fueltransport is difficult, costly or impossible. Examples include satellites, islandcommunities, remote locations and ocean vessels.

4.When grid-connected, solar electric generation can displace the highest costelectricity during times of peak demand (in most climatic regions), can reduce gridloading, and can eliminate the need for local battery power for use in times ofdarkness and high local demand; such application is encouraged by net metering . Time-of-use net metering can be highly favorable to small photovoltaic systems.5. Grid-connected solar electricity can be used locally thus reducingtransmission/distribution losses (transmission losses were approximately 7.2% in1995).

6. Once the initial capital cost of building a solar power plant has beenspent, operating costs are extremely low compared to existing power technologies.

7. Compared to fossil and nuclear energy sources, very little research-money hasbeen invested in the development of solar cells, so there is much room forimprovement. Nevertheless, experimental high efficiency solar cells already haveefficiencies of over 40% and efficiencies are rapidly rising while mass productioncosts are rapidly falling

Advantages

1) Programmable Output Wattage.2) Programmable Charging Current.3) Extendable Output Wattage by use Dual Battery.4) User interface with the help of remote.5) LCD display which displays, Input AC mains Voltage, Load voltage, Load c/n, ACMains Frequency, Inverter frequency. LCD also displays Charge of Battery andBattery Backup with Time remaining to discharge the Battery.6) Switching between Inverter mode and Charging mode within 10ms which avoidsrestarting of computer.
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APPLICATIONSAs far as application areas are concerned our inverter is so feasible, energy savingand easy to install that it can be used anywhere in the houses, schools, colleges,hospitals, industries and institutions etc.1) Uninterrupted Power Supply.2) AC Motor Control.3) Mobile AC power Supplies.4) High-voltage direct current (HVDC) power transmission.5) Emergency Power Supplies for EPABX, Biomedical Instruments.

FUTURE ASPECTS

To overcome the ever increasing demand of electrical energy. By changing theprogram stored in inverter we can change the Frequency of Inverter and it can beused for Induction Heating. Inverters convert low frequency main AC power to ahigher frequency for use in induction heating . Our inverter then changes the DCpower to high frequency AC power.A variable-frequency drive controls the operating speed of an AC motor bycontrolling the frequency and voltage of the power supplied to the motor. Aninverter provides the controlled power. In most cases, the variable-frequency driveincludes a rectifier so that DC power for the inverter can be provided from main AC

power. Since an inverter is the key component, variable-frequency drives aresometimes called inverter drives or just inverters. Our Inverter can be used bychanging its Program.
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Date post:	04-Jun-2018
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Solar Charge Inverter - Electronics for you.

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