PV SYSTEMS, COMPONENTS DEVICES AND APPLICATIONS

 Open circuit voltage Short circuit current  Fill factor  Series resistance  Shunt resistance The current ~voltage characteristics are measured at Standard Test condition STC define

Prabir Kumar DashScientist

Solar Energy Centreprabir.dash@nic.in

 Solar energy is the most abundant source of primary energy ( 7.2 x 1018 kJ/day)

 There are Two methods of harnessing solar energy ( photovoltaic & thermal)

 Method Of Direct Conversion Of Sunlight To

Electricity Using Solid State Devices Is Called

Photovoltaic.

 Generation Is Clean, Quite, and Reliable

 Requires minimum operation & maintenance

 Some cases it is the cheapest option of meeting the

energy requirement.

 A solid state device which produces current when certain range radiation spectrum falls on it

 The operation consists of three steps.

1 Absorption of radiation ( pair production)

2 Charge separation

3 Collection ( flow of electron in the load circuit)

 Various technology devices available are Crystalline

Si, a – Si, thin film technologies like CdTe, CIGS,

GaAs, DSSC and organic cells.

THEORITICAL EFFICIENCY ~BAND GAP ENERGY OF MATERIAL

1 st generation

Silicon wafer

2 nd generation Thin film on glass

3 rd generation Thin film on flexible foil

4 th generation Organic cells.

size Large area deposition Large area deposition Large area printing

Limited cost

reduction potential

Limited cost reduction potential

Low cost potential lowest cost

potential

 Solar cell is the basic building block

of any Solar PV system.

 Open circuit voltage

 Short circuit current

 Fill factor

 Series resistance

 Shunt resistance

The current ~voltage characteristics are measured at Standard Test

condition (STC) defined by three parameters

1 Temperature ( 25 0 C), 2 Irradiance (1000 W/M2 ), 3 Spectrum (1.5G AM)

Inverse of slop at Voc is called series resistance Rs Inverse of slop at Isc is called shunt resistance Rsh

 It is the ratio between power output to power input.

point.

multiplying Irradiance with area of the PV

device.

the efficiency is around 14-19%

 Positive temperature coefficient of current-α

• Current is directly proportional to Irradiance

•Voltage has a logarithmic dependence on irradiance.

 Effect of spectrum depends on the material

characteristics.

 The defining parameter is called spectral response: Amount of current produced per incident power

in watt

 No of cells connected in series/parallel to produce workable current/voltage.

 All cells must be checked for micro cracks or

any other defects.

 Cells to be connected in series must be current matched

 Cells to be connected in parallel must be

voltage matched.

 Grid contacts should be uniform and optimized

to have minimum contact resistance.

 The lamination must not have any air bubble or pores for moisture ingression.

 A bypass diode is connected parallel to the cell string to prevent reverse biasing of the module

at partial/complete shading of the PV module.

PV module so as to prevent back flow of

current in from battery bank to Module at

night.

current of short circuit current at a temperature

Power: 54 Watt (36 * 1,5 W)

Solarmodule

36 Solar cells Voltage 18 Volt (36 * 0,5 V) current: 3 Ampere

Power: 54 Watt (36 * 1,5 W)

Solar generator

18 Solarmodule voltage: 108 Volt (6 * 18 V) current 9 Ampere (3 * 3 A) power: 972 Watt (18 * 54 W)

Solar generator

18 Solarmodule voltage: 108 Volt (6 * 18 V) current 9 Ampere (3 * 3 A) power: 972 Watt (18 * 54 W)

Typical values for standard

conditions:

•radiation G = 1000 W/m²

•Cell temperature T= 25°C

•Air Mass AM = 1.5 G

 Integrated assembly of PV modules and components

to produce power for a particular service.

 May be for electricity generation, pumping water or feeding power to lighting or any mechanical work.

 Because of the modular characteristics, PV systems can be designed to meet the energy demand from few watt to megawatt.

 Most favored for remote application where grid

extension is not possible.

 Can be designed for both AC and DC load.

 Can be classified according to their component configurations, and how the equipment is

connected to other power sources.

GRID CONNECTED SYSTEMS STAND ALONE PV SYSTEMS

 A number of modules assembled together with support structure

is called an array.

 Individual modules produce

electric current and voltage that depends upon the specific

module

 To have the desired voltage and current input we have to connect several modules in parallel/series

 For parallel connection modules must be voltage matched.

 For series connection modules must be current matched

 To hold the module in a required direction without undue stress.

 Support structures to affix the array to either a roof,

a pole, or the ground

 Must be unobstructed to get radiation & accessible for cleaning

 Basically two types - fixed and sun tracking type

 For fixed type panel mounting must be

perpendicular to the noon day sun.

 For tracking sun type provision is there for single or double axis rotational movement.

 Material & mechanical strength of the structure must

be taken into account for design.

 There are following alternatives

• Fixed tilt

• Seasonal tilt

o Winter tilt (O, N, D, J, F, M)

o Summer tilt (A, M, J, J, A, S)

• Single axis tracking (Fixed tilt)

• Dual axis tracking

 Seasonal tilt is most preferred after fixed tilt

 Trackers pose following challenges

• Moving part and hence less reliable

• Bankability

• Higher area

• Additional capital cost

• Higher O&M Cost

 A solar combiner box combines several solar

panels into one dc output to be connected to the charge controller

 A charge controller regulates the amount

of current fed into a Battery bank from

PV array

 Their main function is to prevent overcharging and deep discharge of the batteries, but charge controllers also block battery bank current from leaking back into the PV array at night or on

cloudy days, draining the battery bank.

 It can be done with a normal ON/OFF switch which will connect/disconnect at the desired

voltage of the battery to the PV array.

modulated) and MPPT ( Tracking)

 PWM is a way of digitally encoding analogue signal levels

voltage to optimize the charging process.

 MPPT Match The Maximum Power Point With The Load Voltage.

power point voltage and delivers at load

 It Is An Important Component For Stand Alone PV Systems.

 Chemically stores electrical energy in the daytime & delivers

power when required and renewable source is not available

 A large capacity has to be stored with slow rate of discharge

 Various technologies options are available (Lead-Acid, Ni-Cd,

NiMH, Li- ion etc)

 Flooded lead –acid batteries are very common and cheap, hence widely used for this application

 During sun-less days, batteries are discharged but not charged These conditions result in battery operating in Partial State of

Charge (PSOC) Cycling and Deep cycling Also, solar systems are installed in open atmosphere exposing the batteries to extreme

Temperatures Other lead acid batteries fail in such conditions due

to sulphation, stratification, corrosion and plate shedding

Moreover, remote solar installations make water top-up difficult and costs money

 To meet the above requirement Tubular VRLA batteries are better choice.

 Other options are AGM (absorbent glass mat) & Gel type batteries.

 Specified with capacity & voltage

 Characterized By The following parameters.

1 Number Of Charge Discharge Cycles

2 Depth Of Discharge.

3 Self discharge

4 Charge efficiency

 No of batteries are connected in series/ parallel

to store enough charge to meet the autonomy condition of the PV system.

algebraic sum of individual voltage of a cell.

current get added up.

battery bank for better performance.

Battery bank of 10kW Roof top power plant at SEC

 A solar inverter

Converts the variable

DC to AC of desired frequency and phase.

 Converts DC power from the solar array to AC

to be fed in to the utility grid.

120 volts.

 Converts DC power from the battery to AC for running AC loads.

 Both sine and quasi sine wave out put are

available Selection must be done as per the

per system requirement

 These Are Normal Electrical Components Commonly Used For Electrical Wiring.

 The power consuming component

device.

resistive load

be taken into account on the design stage.

 LED based

3 -5 Wp module, 12 V, 5- 7 Ah @ 20C, SMF Acid/ NiMH with 75 % DoD battery.

Duty cycle: 4 Hrs a day

Autonomy: 3 days

Minimum Efficiency of electronics: 85%

Light out put as follows:

Distance from centre Lux level

 Light Source : White Light Emitting Diode (W-LED)

 Light Out put : White colour (colour temperature 55000-65000K) Minimum 15 LUX when measured at the periphery of 2.5 meter diameter from a height of 2.5 meter At any point within area of 2.5mtr diameter periphery the light level should not be more than three times of the periphery value The illumination should be uniform without dark Bands or abrupt variations and soothing to the eyes Higher output would be preferred

 Mounting of light: Wall or ceiling

 Electronics : Min 85 % efficiency

 Average duty cycle: 5 hours a day

 Autonomy: 3 days (Minimum 12 operating hours per permissible discharge

 Model - 1

One White LED lumaniare

6Wp Module at STC @ 16.4V, battery: SMF type 12 V, 7

Ah @ C/20 with maximum 75 % DoD

 Model - 2

Two White LED lumaniare

12Wp Module at STC @ 16.4V, battery: VRLA type 12 V, 12

Ah @ C/20 with maximum 75 % DoD

 Model – 3 :

Two White LED luminaries and one DC fan of wattage up to

10 W

24Wp Module at STC @ 16.4V, battery: VRLA type 12 V, 20

Ah @ C/20 with maximum 75 % DoD

 Model - 4

Four White LED lumaniare

12Wp Module at STC @ 16.4V, battery: VRLA type 12 V, 12

Ah @ C/20 with maximum 75 % DoD

THERE ARE FOUR MODELS OF HOME LIGHTING SYSTEMS WITH

FOLLOWING DETAILS.

 Light Source: White Light Emitting Diode (W-LED)

 Light Out put: White colour (colour temperature 55000-65000K) minimum 15 LUX when measured at the periphery of 4 meter

diameter from a height of 4 meter The illumination should be

uniform without dark bands or abrupt variations, and soothing to the eye Higher light output will be preferred

 Mounting of light: Minimum 4 metre pole mounted

 PV Module : 40 Wp under STC, measured at 16.4 V at load

Module Voc minimum of 21V

 Battery: Tubular Lead acid Flooded or Tubular GEL / AGM VRLA , 12 V- 40 AH @ C/10, Max DoD 75%

 Electronics Efficiency: Min 85% total

 Duty cycle : Dusk to dawn

 Autonomy : 3 days (Minimum 42 operating hours per permissible discharge

 Rural sector (village lightening, water pumping, community light & TV, Telephone and health centre)

microwave repeater)

station lightning, track circuits)

warning light, cold storage, offshore platform lightening etc.)

SOLAR LANTERN SOLAR HOME

LIGHTING

SYSTEM

SOLAR STREET LIGHTING

SYSTEM

BILL BOARD

LIGHTING

SOLAR LANTERN

SOLAR LIGHT IN A TRIBAL VILLAGE HOUSEHOLD

SOLAR STREET LIGHT IN A VILLAGE IN BASTAR

SOLAR POWERED TV IN A VILLAGE

SOLAR SYSTEM FOR MICROWAVE REPEATER SYSTEM

SOLAR SYSTEM FOR OFF

SHORE PLATFORM

SATELLITE EARTH STATION AT POOH

 Participated in world solar challenge, december

Solar powered Aero plane.

 All cost comparative statements between different sources of energy use the following formula for calculating energy cost Per kWh cost = (Total Construction Cost + Production Cost + Decommissioning Cost)/(MW rating X 1000 X Useful Life X Capacity Factor X 8760)

account.

can be applied to it at 7% per year ( adjusted to inflation).

account health hazard & other environmental & social issues,

it is quite possible we have already passed the tipping point.

thermal PP around 4-8 euro cents/KWh

?