Experiment Manual 14thNov2011

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Experiment Manual guidance e Includes 9 experiment with step-by-step guidanc © Insight Solar, 2011 Ecosense. in[email protected] in[email protected]

2 Develop an in-depth understanding o a Solar PV plant through a real-lie hands on experience.

A

Compact Solar Photovoltaic Module Stand

It consists of two faced Photovoltaic panel, which can be folded and reassembled at use. The module also contains a uniquely designed support stand with adjustable gears for microtilting the PV panel for accurate experiments and readings. This module module also carries two lamps lamps which can be regulated for variable radiation.

Adustable PV Panel

B

Main Controller

This has has been designed designed keeping in in view the user interactivity while connecting the terminals and simultaneously taking the corresponding readings. The main load indicator has been kept at the bottom to avoid the glare in the eye while conducting the experiments. Concealed meters

Protective shield

Regulated lamps

A Collapsible stand

B DC load indicator

AC load indicator

© Insight Solar, S olar, 2011 Ecosense. in[email protected] in[email protected]

2 Develop an in-depth understanding o a Solar PV plant through a real-lie hands on experience.

A

Compact Solar Photovoltaic Module Stand

It consists of two faced Photovoltaic panel, which can be folded and reassembled at use. The module also contains a uniquely designed support stand with adjustable gears for microtilting the PV panel for accurate experiments and readings. This module module also carries two lamps lamps which can be regulated for variable radiation.

Adustable PV Panel

B

Main Controller

This has has been designed designed keeping in in view the user interactivity while connecting the terminals and simultaneously taking the corresponding readings. The main load indicator has been kept at the bottom to avoid the glare in the eye while conducting the experiments. Concealed meters

Protective shield

Regulated lamps

A Collapsible stand

B DC load indicator

AC load indicator


Insight Solar Experiment Introduction

Insight Solar

Introduction This experimental experimental manual manual is prepar prepared ed specically or the users o “Insight Solar PV training kit”. This manual covers the undamentals o solar PV system which would be helpul to the engineering students o both undergraduate and postgraduate level. The manual is divided in two parts. Part I ocuses on the characteristics o PV module at dierent conditions. Part II ocuses on the characteristics o PV system and power ow analysis. Part I comprises ve experiments. Experiment 1 helps to evaluate current-voltage characteristics o single PV module while Experiment 2 ocuses on evaluating currentvoltage characteristics o combination o two PV modules in series and parallel. These two experiments also help to evaluate ll actor o PV module. Experiment 3 explains how incident radiation and power output o module gets changed with change in tilt angle o PV module. Experiment 4 shows the eect o shading o cells o PV module. This experiment uses some shading blades or shading the solar cells. Experiment 5 helps to explains the working o diode as blocking and bypass diode. Part II consists o our experiments. Experiment 1 demonstrates and explains the power ow o PV system when DC load connected to it. Similarly, Experiment 2 does the same when AC load is connected. These

two experiments explains the working o stand-alone PV system with either DC and AC load. Experiment 3 explores the complete stand alone PV system with both DC and AC load. Experiment 4 ocuses on the charging and discharging characteristics o battery. This experiment experiment is about about voltage and current current variation with charging and discharging.

DOs

DON’Ts

• Alwa Always yspe perfo rform rmt the he experimentwithat leasttwostudents.

• Don’t Don’tex expo pose set the he controllerunitin water.

• Alwa Always yss sta tart rtth the e experimentwithPV modulecleaning.

• Don’t Don’ts short hortt the he batteryterminals oranyothersource terminals.

• Make Makes sur ure eal alll connectionsaretight. • Note Noteal alllre read adin ings gs ofdierentmeters simultaneously. • Cond Conduct ucton one eset setof of eachexperiment within2-3minutes. • Foll Follow owa allllt the he precautionsgivenat theendofexperiment.

• Don’ Don’tmo t move vet the he halogenorPVmodule whiletheexperiment isgoingon. • Don’t Don’tc con onnec nect tth the e moduleo/ptothe chargecontroller beforeconnectingthe batterywithcharge controller. • Don’t Don’ta allllow owt the he moduletemperature above700C.

© Insight Solar, 2011 Ecosense. in[email protected] in[email protected]

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Insight Solar Experiment no. 1

Insight Solar

Experiment no. 1 Objective To demonstrate To demonstrate the I-V and P-V P-V characteristics o PV module with varying radiation and temperature level.

Theory PV module is characterized by its I-V and P-V characteristics. At a particular solar insolation and temperature, module characteristic curves are shown in Fig. 1.1(a) and 1.1(b) respectively. 2,500 2,000 ) A ( 1,500 t n e r 1,000 r u C 0,500 0,000 00 .0 .050

.1 0. 0.15

0.20 .2 .250

.3 0. 0.35

0.40 0.45

.5 0.55

Characteristic curves of solar cell In I-V characteristic maximum current at zero voltage is the short circuit current (Isc) which can be measured by shorting the PV module and maximum voltage at zero current is the open circuit voltage (V oc oc). In P-V curve the maximum power is achieved only at a single point which is called MPP (maximum power point) and the voltage and current corresponding to this point are reerred as V mp mp and I mp. On increasing the temperature, Voc o module decreases as shown in Fig. 1.2, while Isc remains the same which in turn reduces the power. For most crystalline silicon solar cells modules the reduction is about 0.50%/°C.

0.6

Voltage (V)

Fig. 1.1(a). I-V characteristic o PV module 1,200 1,000

) W0,800 ( r 0,600 e w o P0,400 0,200 0,000 00 .050

.1 0.15

0.20 .250

.3 0.35

0.40 0.45

.5 0.55

0.6

Voltage (V)

Fig. 1.1(b). P-V characteristic o PV module


Fig. 1.2. Variation in V oc oc with change in temperature


I

On changing the solar insolation I sc o the module increases while the V oc increases very slightly as shown in Fig. 1.3.

PT

ISC IMP PMAX

2

1000W /m

2 V

A n i t n e r r u1 C

000

MP

,1

600W/m

2

200W/m

2

0,20

,3

Experimental set-up 0,40

,5

Fig. 1.3. Variation in I-V characteristic with insolation

Fill actor: The Fill Factor (FF) is essentially a measure o quality o the solar cell. It is the ratio o the actual achievable maximum power to the theoretical maximum power (P T )that would be achieved with open circuit voltage and short circuit current together. FF can also be interpreted graphically as the ratio o the rectangular areas depicted in Fig.1.4. A larger ll actor is desirable, and corresponds to an I-V sweep that is more square-like. Typical ll actors range rom 0.5 to 0.82. Fill actor is also oten represented as a percentage.

=

V

OC

Fig. 1.4. Graphical interpretation o the Fill actor (FF)

Voltage in V

P MAX FF = P T

V

I MP • V MP I SC • V OC

The circuit diagram to evaluate I-V and P-V characteristics o a module is shown in Fig.1.5. Form a PV system which includes PV module and a variable resistor (pot meter) with ammeter and voltmeter or measurement. Pot meter in this circuit works as a variable load or the module. When load on the module is varied by pot meter the current and voltage o the module gets changed which shit the operating point on I-V and P-V characteristics. A

V

Pot meter

Fig. 1.5. Circuit diagram or evaluation o I-V and P-V characteristics

PV characteristics evaluation can be achieved by ollowing connections in control board (as shown in Fig.1.6).

© Insight Solar, 2011 Ecosense. in[email protected]

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Controller connections

Observations: Table or I-V and P-V characteristics o PV module :

Module Temperature LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

Module Voltage DC Load

Battery 1

2

Solar Charge Controller DC I/P

AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2

Inv. Input Voltage POT Meter

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

These 4 sets are or dierent radiation and temperature levels but in one set the values o radiation and temperature will be constant.

Results:

Fig. 1.6. Control board connections to get I-V and P-V characteristics


1. Draw the I-V curves o all the sets on a single graph and show the characteristics at dierent radiation and temperature levels.


2. Draw the P-V curves o all sets on a single graph and show the characteristics at dierent radiation and temperature levels. 3. Calculate the ll actor or the given module.

Precautions:

experiment) otherwise temperature o the module may vary as radiation source used is halogen lamp. 2. Halogen lamp position should not be changed during one set otherwise radiation on modules will change. 3. Connections should be tight.

1. Readings or one set should be taken within 1-2 minutes (or indoor

Notes


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Insight Solar

Experiment no. 2 Objective

Pmax

Fig. 2.1(b). I-V characteristic o parallel connected modules

To demonstrate the I-V and P-V characteristics o series and parallel combination o PV modules. I(A)

Theory

Pmax

PV module is characterized by its I-V and P-V characteristics. At a particular level o solar insolation and temperature it will show a unique I-V and P-V characteristics. These characteristics can be altered as per requirement by connecting both modules in series or parallel to get higher voltage or higher current as shown in Fig. 2.1(a) and 2.1(b) respectively. Pmax

Pmax

I(A)

Voc

Voc

Voc Voltage(v)

Thereore, i modules are connected in series then power reduction is twice when connected in parallel. On changing the solar insolation, I sc o the module increases while the V oc increases very slightly, thereore there is overall power increase. In parallel connection power increment is twice than when connected in series.

Voltage(v)

Fig. 2.1(a). I-V characteristic o series connected modules

On increasing the temperature, V oc o modules decrease while I sc remains same which in turn reduces the power.


Experimental set-up The circuit diagram to evaluate I-V and P-V characteristics o modules connected in series and parallel are shown in Fig. 2.2(a) and 2.2(b) respectively.


Form a PV system with modules in either series or parallel and a variable resistor (Pot meter) with ammeter and voltmeter or measurement. Modules in series or parallel are connected to variable load (pot meter). The eect o load change on output voltage and current o the modules connected in series or parallel can be seen by varying load resistance (pot meter). A

Series connected modules


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current


V

Battery 1

2

Pot meter Solar Charge Controller DC I/P

AC Load

Module Output 1

DC Load

Battery / Inverter

Fig. 2.2(a). Circuit diagram or evaluation o I-V and P-V characteristics o series connected modules A

Module Output 2


Inv. Input Current

V

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

Pot meter

Fig. 2.2(b). Circuit diagram or evaluation o I-V and P-V characteristics o parallel connected modules

I-V and P-V characteristics o the modules connected in series or parallel can be achieved by connections shown in Fig. 2.3(a) and (b) respectively.

Fig. 2.3(a). Control board connections or modules connected in series


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Parallel connected modules

Observations: Table or I-V and P-V characteristics o PV modules in series:


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current


Battery 1

2


AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2


Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

Fig. 2.3(b). Control board connections or parallel connected modules



Table or I-V and P-V characteristics o PV modules in parallel:


connected in series and parallel and show the characteristics at dierent radiation and temperature levels. 2. Draw the P-V curves o all the 3 sets on a single graph or the modules connected in series and parallel and show the characteristics at dierent radiation and temperature levels.

Precautions:


Results: 1. Draw the I-V curves o all the 3 sets on a single graph or the modules

1. Readings or one set should be taken within 1-2 minutes (or indoor exp.) otherwise temperature o the module may change as radiation source used is halogen lamp. 2. Halogen lamp position should not be changed during one set otherwise radiation on modules will change. 3. Connections should be tight.

Notes


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Insight Solar

Experiment no. 3 Objective To show the eect o variation in tilt angle on PV module power.

Spring & Fall Tilt angle is set at latitude

Theory Tilt is the angle between the plane surace under consideration and the horizontal plane. It varies between 0-90 0. PV arrays work best when the sun’s rays shine perpendicular to the cells. When the cells are directly acing the sun in both azimuth and altitude, the angle o incidence is normal. Thereore, tilt angle should be such that it aces the sun rays normally or maximum number o hours.

Summer

Tilt angle is set at latitude minus 15 degrees

Fig. 3.1. Tilt angle settings or diferent seasons


Winter

Tilt angle is set at latitude plus 15 degrees

The tilt angle settings or dierent seasons are shown in Fig. 3.1. PV systems that are designed to perorm best in the winter, array should be tilted at an angle o equal to latitude +15°. I the array is designed to perorm best in the summer, then the array needs to be tilted at an angle o equal to latitude−15°. In this way the array surace becomes perpendicular o the sun rays. For best perormance throughout the year, tilt should be equal to the latitude angle.


Experimental set-up The tilt angle o the module can be changed by rotating the lever below the module. Lit the halogen lamp and change the tilt o the module by rotating the lever.



Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current


Battery 1

2


AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2


Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

Fig. 3.2. Arrangement to vary tilt o the module

To evaluate eect o tilt on power output o the module, ollowing connections are to be done in the control board as shown in Fig. 3.3. The pot meter in this case has to be xed at constant position so that the eect o tilt can be seen.

Fig. 3.3. Control board connections to evaluate efect o tilt


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Observations:

Results

Tables or evaluating eect o tilt: Each set is or the dierent positions o pot-meter but during one set its position will be xed. Radiation on module will be calculated by taking an average o the radiations recorded at three dierence locations on the module (viz. upper end, middle and lower end).

Draw the graph between tilt (as x-axis) and Radiation and Power (on let and right y-axis). Relation between radiation and power o/p will be linear.

Precautions: 1. Readings or one set should be taken within 1-2 minutes (or indoor exp.) otherwise temperature o the module may vary as radiation source used is halogen lamp. 2. Observations or tilt angle should be taken as correct as possible. 3. Always take radiation reading ater module current and voltage readings. 4. Connections should be tight.

Notes



Insight Solar

Experiment no. 4 Objective

Experimental set-up

To demonstrate the eect o shading on module output power.

There are some shading elements o the string size which can cover the string o module completely. For executing this experiment, put one o these shading elements on one string to shade it completely. Ater this shade two parallel connected strings. For conducting this experiment do the connections as shown in Fig. 4.2.

Theory There are 36 solar cells in a module. These 36 solar cells are in series as shown in Fig. 4.1 which makes the module as series connected solar cells.

Fig. 4.1. Internal structure o the module

These cells are in series without bypass diode so shading o one cell will be sufcient to reduce the power to zero. This arrangement gives zero power i the entire row o cells gets shaded.


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Observations: Table or evaluating the eect o shading on cells:


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current


Battery 1

2

Results: 1. Demonstrate the power output o module with one string shaded.


AC Load

Module Output 1

DC Load

Battery / Inverter

2. Demonstrate the power output o module with two strings shaded.

Module Output 2

Precautions:


1. Shading o string should be exactly on that string only.

Inv. Input Current

2. Connections should be tight. Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

Fig. 4.2. Control board connections



Insight Solar

Experiment no. 5 Objective To demonstrate the working o diode as Bypass diode and blocking diode.

Theory Diode is very important element in the PV system. This element can work as a blocking diode or as a bypass diode. Diodes connected in series with cells or modules are called blocking diodes and diodes connected across cells or modules are called bypass diodes. There are two situations where these diodes can help.

sunlight is not available. The battery could discharge at night time by owing current backwards through the module. This would not be harmul to the module, but would result in loss o precious energy rom the battery bank. To prevent the current ow rom the battery to the module at night time blocking diode is placed in the circuit between the module and the battery. Circuits with and without diodes are shown in ollowing gures.

Bypass action o diode I two modules are in series then the current in circuit will be decided by the module which is generating less current. Hence i one module is completely shaded then the current in the circuit will be zero. I there is a diode in parallel with the shaded module then power output o non-shaded module gets bypassed by diode and will be available at load terminals.

Blocking reverse fow o current rom the battery through the module at night. In battery charging systems, the module potential drops to zero at night when

+

Fig. 5.1. Diode in blocking mode in series connected modules

Blocking reverse fow down through damaged module rom parallel connected modules during the day. Blocking diodes placed at the head o separate series wired strings in high voltage systems can perorm yet another


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unction during daylight conditions. I one string becomes severely shaded, or i there is a short circuit in one o the modules, the blocking diode prevents the other strings rom loosing current backwards down the shaded or damaged string. The shaded or damaged string is “isolated” rom the others, and more current is sent on to the load. In this conguration, the blocking diodes are sometimes called “isolation diodes”. A

+

V

-

Shaded diode

Fig. 5.2. Diode in blocking mode in parallel connected modules

Experimental set-up There are two diodes which can be used as a blocking diode as well as bypass diode.


a) Diode in bypass mode in series connected modules Shade one module completely and connect the diode in parallel with shaded module terminals (as shown in Fig. 5.3.). b) Diode in blocking mode in series connected modules with batteries In blocking action o series connected modules a diode is connected in series with series connected modules. This protects the module rom reverse current ow rom battery. Connections as shown in Fig. 5.4. c) Diode in blocking mode in parallel connected modules In parallel connected modules the diode is connected in series with the shaded module and this protects the shaded module rom reverse current ow (generated by other module). Connections as shown in Fig. 5.5.



Module Temperature


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

Module Voltage


Battery 1

2

Solar Charge Controller

DC Load

Battery 1

2


AC Load

DC I/P

Module Output 1

DC Load

AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2

Inv. Input Voltage

Battery / Inverter

Module Output 2


Inv. Input Current

POT Meter

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

DC Load Current

DC Load Voltage

Fig. 5.3a. Series connected modules without bypass diode

Fig. 5.3b. Series connected modules with bypass diode


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Module Temperature


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

Module Voltage


Battery 1

2


DC Load

Battery 1


AC Load

DC I/P

Module Output 1

DC Load

AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2

Inv. Input Voltage

Battery / Inverter

Module Output 2


Inv. Input Current

POT Meter

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

DC Load Current

DC Load Voltage

Fig. 5.4a. Series connected modules with batteries and without blocking diode


Fig. 5.4b. Series connected modules with batteries and with blocking diode

2



Module Temperature


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

Module Voltage


Battery 1

2


DC Load

Battery 1

2


AC Load

DC I/P

Module Output 1

DC Load

AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2

Inv. Input Voltage

Battery / Inverter

Module Output 2


Inv. Input Current

POT Meter

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

DC Load Current

DC Load Voltage

Fig. 5.5a. Parallel connected modules without blocking diode

Fig. 5.5b. Parallel connected modules with blocking diode


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Observations: 1. Power output o series connected modules beore using bypass diode with shaded module will be close to zero. Ater using bypass diode with shaded module, power output o series connected modules gets increased rom nearly zero to higher value.

Notes


2. Connections with two congurations o blocking mode without using diode, LED will glow in these two cases showing reverse current ow. 3. Connections with two congurations o blocking mode using diode, LED will not glow in these two cases.


Insight Solar

Experiment no. 6 Objective Workout power ow calculations o standalone PV system o DC load with battery.

Theory Stand alone PV system (Fig. 6.1) is the one which can be used or both AC and DC loads and installed near the location o load. These systems are easy to install and understand. These systems can be used without batteries also, but these systems perorm best with battery bank. These systems are best suited or the locations

where grid connectivity is not present and these systems ulll the requirements o these locations. Stand alone PV system o DC type is used when local loads consist o DC equipments and battery storage only. This system consists o PV module, charge controller, battery and DC load. Charge controller regulates the module voltage at 12V or any other value o voltage, required by the battery bank or load and then powered the load. In this system there is no need o Inverter so efciency o system is high because DC to AC conversion stage is absent.

Experimental set-up The demonstration o stand alone PV system with only DC load can be done in the ollowing ways: a) Using only single module (Fig.6.2a) b) Using modules in parallel (Fig.6.2b) c) Using modules in series (Fig.6.2c) Fig. 6.1. Stand alone PV system


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Module Temperature


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

Module Voltage


Battery 1

2


DC Load

Battery 1

2


AC Load

DC I/P

Module Output 1

DC Load

AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2

Inv. Input Voltage

Battery / Inverter

Module Output 2


Inv. Input Current

POT Meter

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

DC Load Current

DC Load Voltage

Fig. 6.2a. Demonstration o DC load with single module (12 V system)


Fig. 6.2b. Demonstration o DC load with parallel connected modules (12 V system)




Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current


Battery 1

2


AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2


Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

Fig. 6.2c. Demonstration o DC load with series connected modules (24 V system)


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Observations The parameters to be observed are DC load current, DC load voltage, battery current and battery voltage with dierent series/parallel combinations o modules. Tables or Stand-alone PV system calculation:

Results

Precautions

Show the power balance by ollowing ormula:

1. Readings should be taken careully.

Array power = load power + battery power + Power loss by charge controller

2. Always plug-in the module power lead at the input o charge controller, ater connecting the battery terminals with charge controller output terminals. 3. Connections should be tight.

Note:Batterypowerwillbewith–vesignif batteryisdischargingthroughload.Current consumptionofChargecontrolleris4mA.

Notes



Insight Solar

Experiment no. 7 Objective Workout power ow calculations o standalone PV system o AC load with battery.

Theory Stand alone PV system (Fig. 7.1) is the one which can be used or both AC and DC loads and installed near the location o load. These systems are easy to install and understand. These systems can be used without batteries also, but these systems perorm best with battery bank. These

systems are best suited or the locations where grid connectivity is not present and these systems ulll the requirements o these locations. Stand alone PV system o AC type requires inverter to convert DC voltage available at the charge controller output to controlled AC voltage o required magnitude to supply AC type o load. This system consists o Modules, charge controller, battery and inverter. Charge controller regulates the module voltage to 12 volt and charge the battery and then this regulated DC power is converted to AC by means o inverter. Inverter efciency is approximately 95%.

Experimental set-up The demonstration o stand alone PV system with only AC load can be done in the ollowing ways: a) Using only single module (Fig.7.2a) b) Using modules in parallel (Fig.7.2b) Fig. 7.1. Stand alone PV system


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ModuleTemperature


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

Module Voltage


Battery 1

2


DC Load

Battery 1


AC Load

DC I/P

Module Output 1

DC Load

AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2

Inv. Input Voltage

Battery / Inverter

Module Output 2


Inv. Input Current

POT Meter

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

DC Load Current

DC Load Voltage

Fig. 7.2a. Demonstration o AC load with single module


Fig. 7.2b. Demonstration o AC load with parallel connected modules

2


Observations The quantities to be observed are AC load current, AC load voltage, inverter input voltage, current, battery current and battery voltage with dierent parallel combinations o modules. Tables or Stand-alone PV system calculation:

Table or inverter efciency:

Results

Precautions

Show the power balance in both the sets by ollowing ormulae:


1. Array power = Inverter i/p power + battery power + loss due to charge controller 2. Inverter efciency = AC load power*100/Inverter input power (DC)




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Insight Solar

Experiment no. 8 Objective Workout power ow calculations o standalone PV system o DC and AC load with battery.

Theory Stand alone system (Fig. 8.1) is the one which can be used or both AC and DC loads and installed near the location o load. These systems are easy to install and understand. These systems can be used without batteries also but these systems

perorm best with battery bank. These systems are best suited or the locations where grid connectivity is not present and these systems ulll the requirements o these locations. This system use DC power to charge the battery and run the DC load but, use AC power to run the AC load. There are modules, charge controller, batteries, DC load, inverter and AC load in this system. This system runs the AC and DC load simultaneously and can ulll the demand o the both types o loads.

Experimental set-up The demonstration o stand alone PV system with AC & DC load can be done in the ollowing ways: a) Using only single module (Fig.8.2a) b) Using modules in parallel (Fig.8.2b)

Fig. 8.1. Stand alone PV system




Module Temperature


Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current

Module Voltage


Battery 1

2


DC Load

Battery 1

2


AC Load

DC I/P

Module Output 1

DC Load

AC Load

Module Output 1

DC Load

Battery / Inverter

Module Output 2

Inv. Input Voltage

Battery / Inverter

Module Output 2


Inv. Input Current

POT Meter

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

DC Load Current

DC Load Voltage

Fig. 8.2a. Demonstration o AC & DC load with single module

Fig. 8.2b. Demonstration o AC & DC load with parallel connected modules


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Observations Tables or Stand-alone PV system calculation:

Table or inverter efciency:

Results

Precautions

Show the power balance in both the sets by ollowing ormulae:


1. Array power = DC load power +AC load power + battery power+ loss due to charge controller. 2. Inverter efciency = AC load power*100/Inverter input power





Insight Solar

Experiment no. 9 Objective To draw the charging and discharging characteristics o battery.

Theory

o discharging voltage variation becomes less steeper and battery discharge up to somewhat higher voltage. The typical 12V, 3Ah battery discharge characteristic is shown in Fig. 9.1.

Battery discharging

Battery charging

Battery discharging depends on magnitude o current drawn and the time or which this current is drawn. Rate o charge owing determined the steepness o discharge characteristic. At higher current i.e. at higher rate o discharge, voltage variation becomes more steeper and battery discharge up to much low voltage. Similarly, at lower rate

Starting current o charging is much higher because the voltage o the discharged battery is low. Initially battery draws almost constant charging current while battery voltage increases rapidly, as soon as battery voltage reaches rated voltage, charging current start reducing rapidly and battery voltage becomes constant. Ater ully charging, the battery charging current reduces to vary low value required to trickle charge the battery. The typical charge characteristic o 12V battery is shown in Fig. 9.2.

0

Discharge characteristic (25C )

13.0

e e g r m u a l h o C V

12.0

(%)( 140

11.0 10.0

0.77A 0.44A 0.225A 1.23A

120

CA) ( 1 2V)

15

0.20

14

0.15

13

0.10

12

20

0.05

11

0

0

80 60 40

0 23

5

10 20 30

h

e g a t l o V

0.25

100

9.0

t n e r r u C

e g a t l o V

Charge Volume

Charge Voltage

Charge Current

Charge Time (H)

Fig. 9.1. Battery discharging characteristics

Fig. 9.2. Battery charging characteristics


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Experimental set-up


To demonstrate charge and discharge characteristics o the battery connections, do the connections in control board as shown in Fig. 9.3(a) and 9.3(b).

Battery discharging

Battery charging Module Temperature LED

Diode 1

Diode 2

I nv er te r I /P

I nv er te r O /P

Module Current


Diode 1

Diode 2


Module Current

Battery 1

Solar Charge Controller I nv er te r I /P

I nv er te r O /P

DC I/P

AC Load

Module Output 1

DC Load Module Voltage DC Load

Battery 1

2


Battery / Inverter

Module Output 2

Inv. Input Voltage DC I/P

AC Load

POT Meter

Module Output 1

DC Load

Inv. Input Current Battery / Inverter

Module Output 2


Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

Inv. Input Current

Batt. Input Current

Batt. Input Voltage

Gen. AC Current

Gen. AC Voltage

DC Load Current

DC Load Voltage

Fig. 9.3 (a).


Fig. 9.3 (b).

2


Observations Discharging experiment can be done at dierent current values. This can be achieved by changing the load. Table or discharging o battery:

Table or charging o battery:

Results 1. Draw charging and discharging curves by taking time (in hrs) on x-axis and voltage and current on y-axis..

2. Always plug-in the module power lead at the input o charge controller, ater connecting the battery terminals with charge controller output terminals. 3. Connections should be tight

Precautions 1. Connections o battery should be made careully.


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Insight Solar Notes

Notes


Insight Solar Notes

Notes


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Insight Solar Notes

Notes


Insight Solar Notes

Notes


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Experiment Manual 14thNov2011

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