Download Cells, Modules and Arrays

Chapter 5
Cells, Modules and Arrays
Principles of Operation ● I-V Characteristics ● Response
to Irradiance and Temperature ● Series/Parallel
Connections ● Specifications and Ratings
 2012 Jim Dunlop Solar
Overview
 Describing the photovoltaic (PV) effect and comparing the fabrication of
solar cells from various manufacturing processes.
 Defining the current-voltage (I-V) characteristic for a PV device and the
key operating parameters.
 Understanding how sunlight, temperature and electrical load affect the
output of a PV device.
 Determining the electrical output of similar and dissimilar PV devices
connected in series and parallel.
 Explaining the purpose and operation of bypass diodes.
 Describing the performance rating conditions and labeling requirements
for PV modules.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 2
Cells, Modules and Arrays
Cell
Module
Array
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 3
Solar Cells
 Solar cells are semiconductor devices that convert sunlight to DC
electricity.
(-)
Electrical
Load
Photovoltaic cell
DC current flow
Boron-doped silicon
(P-type) wafer < 250 μm
 2012 Jim Dunlop Solar
Phosphorous-doped silicon
(N-type) layer ~ 0.3 μm
(+)
Cells, Modules and Arrays: 5 - 4
The Photovoltaic Effect
 The photovoltaic effect is the process of creating a voltage
across charged materials that are exposed to electromagnetic
radiation.
 Photons in sunlight impart their energy to excess charge carriers
(electrons and holes) allowing them to freely move about the
material.
 Charge opposition between the two materials creates an
electrical field that provides momentum and direction to the free
charge carriers, resulting in the flow of electrical current flow
when the cell is connected to a load.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 5
Silicon Solar Cells
 Silicon solar cells produce about 0.5 to 0.6 volt independent of
cell area, depending on temperature.
 The current output of a solar cell depends primarily on the cell
area, its efficiency, and the incident solar radiation.
 Modern silicon solar cells are up to 8 inches in diameter and
produce up to 4 watts and 8 amps under full sunlight.
Monocrystalline cell
 2012 Jim Dunlop Solar
Polycrystalline cell
Cells, Modules and Arrays: 5 - 6
Crystalline Silicon Wafer Production
 The following processes are commonly used to create P-type
silicon wafers:

The Czochralski method produces a single or monocrystalline wafer.

The cast ingot method produces a multigrain or polycrystalline wafer.

The ribbon method produces polycrystalline wafers by drawing molten
silicon between dies in a continuous process.
 Wafer are additionally processed to produce a complete solar
cell.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 7
Moncrystalline Wafer Production:
Czochralski Method
 Single crystal or monocrystalline
silicon wafers are grown in the
form of a cylindrical ingot,
creating a perfect crystal.
 A seed crystal is inserted into
molten polysilicon doped with
boron, rotated and drawn
upward allowing the P-type
silicon material to cool into a
cylindrical ingot.
Czochralski Method
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 8
Polycrystalline Silicon Wafer
Production
 Polycrystalline or multicrystalline silicon wafers are
cast, forming a block-shaped
ingot that has many crystals.
 Molten polysilicon doped with
boron is poured into a
rectangular crucible, and slowly
cooled at controlled rate.
 Polycrystalline wafers are also
made using the ribbon method.
 2012 Jim Dunlop Solar
Cast Ingot Method
Cells, Modules and Arrays: 5 - 9
Solar Cell Manufacturing
 Once a P-type silicon ingot is produced, a number of additional
steps are required to create an actual solar cell.
Cropping
Sawing
Phosphorous diffusion
Screen printing
 2012 Jim Dunlop Solar
Electrical testing
SolarWorld USA
Cells, Modules and Arrays: 5 - 10
Flat-Plate PV Modules
 Flat-plate PV modules respond to both direct and diffuse solar
radiation, and are the smallest field installable generating unit.
SolarWorld
Single (mono) crystalline
 2012 Jim Dunlop Solar
Polycrystalline
Cells, Modules and Arrays: 5 - 11
Flat-Plate PV Modules
Polycrystalline
Single (mono) crystalline
36 cell modules
60 cell polycrystalline module
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 12
Typical PV Module Construction
Continuous silicone seal
Tempered glass
EVA embedding
Tough polymer
back sheet
Solar cells
High strength frame
SolarWorld USA
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 13
Emerging PV Module
Technologies
 Thick wafer silicon P-N junction solar cells are considered first
generation PV devices.
 Second generation devices are thin-film devices including:

Amorphous silicon (a-Si)
 Cadmium Telluride (CdTe)
 Copper indium gallium selenide (CIS or CIGS)
 Other advanced PV module designs include:

Concentrating PV modules
 AC modules
 Polymer and organic solar cells
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 14
Thin-Film PV Modules
 Thin-film PV modules are
produced by depositing ultrathin layers of semiconductor
materials on a flexible or rigid
substrate.
 Thin-film modules have
significant potential for cost and
weight reductions.
 Disadvantages include lower
efficiencies and higher
degradation rates than
crystalline silicon modules.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 15
Concentrating PV Modules
 Use optics to focus sunlight on
solar cells up to 200-500 X.
 Employ advanced multijunction
solar cells approaching
efficiencies of up to 40%.
 Utilize only direct component of
total global solar radiation, and
employ two-axis sun tracking.
 Design challenges include
managing high temperatures and
high DC currents.
NREL, Bill Timmerman
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 16
AC Modules and Micro-Inverters
 Alternating-current (AC) modules
are an integrated PV module and
inverter product intended for
installation as a single unit.
 AC modules do not have any
field-installed DC wiring.
 Micro-inverters are separate
module level inverters intended
for field installation.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 17
Photovoltaic Arrays
 PV arrays are constructed from building blocks of individual PV
modules, panels and subarrays that form a mechanically and
electrically integrated DC power generation unit.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 18
Photovoltaic Arrays
Ground-mounted rack array
Pole-mounted tracking array
Standoff roof-mounted array
Building-integrated array
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 19
Photovoltaic Arrays
Roof-mounted standoff array
Roof-mounted rack array
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 20
Leading Manufacturers of
PV Cells and Modules
 BP Solar
 Schott Solar
 First Solar
 Sharp Solar
 JA Solar
 SolarWorld
 Kyocera
 SunPower
 Mitsubishi
 Suntech
 Motech
 Trina
 Q-Cells
 Yingli
 Sanyo
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 21
Current-Voltage (I-V)
Characteristic
 The electrical performance of a
PV device is given by it currentvoltage (I-V) curve.
 Represents an infinite number of
I-V operating points.
 Varies with solar radiation and
device temperature.
Voltage (V)
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 22
Key I-V Parameters
 PV device performance is
specified by the following I-V
parameters at a given
temperature and solar irradiance
condition:
Isc
Pmp
Imp





Open-circuit voltage (Voc)
Short-circuit current (Isc)
Maximum power point (Pmp)
Maximum power voltage (Vmp)
Maximum power current (Imp)
Area = Pmp
Voltage (V)
 2012 Jim Dunlop Solar
Vmp
Voc
Cells, Modules and Arrays: 5 - 23
Power vs. Voltage Curve
Current vs. Voltage
Power vs. Voltage
Pmp
Isc
Imp
Pmp = Imp x Vmp
Voltage (V)
 2012 Jim Dunlop Solar
Vmp
Voc
Cells, Modules and Arrays: 5 - 24
PV Module Rating Conditions
 The electrical performance of PV
modules is rated at Standard Test
Conditions (STC):
Irradiance: 1,000 W/m2 , AM 1.5
 Cell temperature: 25°C

 2012 Jim Dunlop Solar
Source: SolarWorld USA
Cells, Modules and Arrays: 5 - 25
Fill Factor
 Fill factor (FF) is an indicator of the quality of a solar cell.

FF = (Vmp x Imp) / (Voc x Isc) = Pmp / (Voc x Isc)
Isc
Imp
Pmp = Imp x Vmp
Isc x Voc
Voltage (V)
 2012 Jim Dunlop Solar
Vmp
Voc
Cells, Modules and Arrays: 5 - 26
Efficiency
 Efficiency of a PV device is the
ratio of the electrical power
output and the solar irradiance
input over the device area,
expressed as a percentage:
η=
Pmp
E× A
where
η = efficiency
Pmp = maximum power rating (W)
E = solar iradiance (W/m 2 )
A = surface area (m 2 )
 Example:

What is the efficiency for a PV
module that has a surface area of
1.4 m2, and produces 200 W
maximum power when exposed to
1000 W/m2 solar irradiance?
 2012 Jim Dunlop Solar
η=
η=
Pmp
E× A
200 W
(1000 W/m 2 × 1.4 m 2 )
=
= 14.3%
η 0.143
Cells, Modules and Arrays: 5 - 27
Response to Electrical Load
 The electrical load connected to a PV device determines its
operating point.

If a battery is connected to a PV device, the battery voltage sets the
operating voltage for that PV device.
 In a grid-connected PV system, the inverter loads the PV array at its
maximum power point.
 From Ohm’s Law, the electrical load resistance that operates a PV
device at its maximum power point is equal to Vmp/Imp (ohms).
+
PV Device
-
 2012 Jim Dunlop Solar
Electrical
Load
Cells, Modules and Arrays: 5 - 28
Operating Point
Isc
Imp
Pmp = Imp x Vmp
Voltage (V)
 2012 Jim Dunlop Solar
Vmp
Voc
Cells, Modules and Arrays: 5 - 29
PV Modules for
Battery Charging
PV module maximum power voltage must be higher
than battery voltage at highest operating temperature
Current (A)
Operating voltage range for 12-volt lead-acid battery:
11.5 to 14.5 volts.
Maximum power points
Module with 42 series-connected cells at 50°C
(voltage is more than adequate for charging,
but power is wasted)
Module with 30 series-connected
cells at 50°C (voltage too low to
deliver maximum current to battery)
10
Module with 36 series-connected cells
operating at temperature of 50°C (optimal)
20
Voltage (V)
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 30
Effect of Electrical Load on
Operating Point
Decreasing
R=0
resistance
Increasing
resistance
Load lines of constant
resistance
Constant Temperature
R=
Voltage
 2012 Jim Dunlop Solar
∞
Cells, Modules and Arrays: 5 - 31
I-V Measurement Methods
Electrolytic
capacitor
A
V
Variable
resistor
PV Device
 2012 Jim Dunlop Solar
Variable
battery
Cells, Modules and Arrays: 5 - 32
Solmetric PVA-600 PV Analyzer
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 33
Raydec DS-100 IV Curve Tracer
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 34
Spire 4600 SLP Flash Simulator
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 35
Response to Electrical Load:
Example
 The maximum power voltage (Vmp) and maximum power current
(Imp) for a PV module are 35.8 volts and 4.89 amps, respectively.
What is the maximum power and load resistance required to
operate at maximum power?
 The maximum power is calculated by the product of the
maximum power voltage and maximum power current:
35.8 volts x 4.89 amps = 175 watts
 From Ohm’s Law, resistance is equal to the voltage divided by
the current:
35.8 volts / 4.89 amps = 7.32 ohms
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 36
Solar Cell Equivalent Circuit
 A solar cell equivalent circuit consists of a current source in
parallel with a diode and shunt resistance, connected to a series
resistance.
Series resistance
Current
source
 2012 Jim Dunlop Solar
Diode
Shunt resistance
Load resistance
Cells, Modules and Arrays: 5 - 37
Series Resistance
Low Rs
Increasing Rs decreases
Pmp, Vmp and Imp, and
also reduces FF and
efficiency.
Moderate Rs
High Rs
Rs = - ∆V / ∆ I
∆I
∆V
Voltage
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 38
Shunt Resistance
Decreasing Rsh decreases
Pmp, Vmp and Imp.
∆I
∆V
Rsh = - ∆V / I
High Rsh
Moderate Rsh
Low Rsh
Voltage
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 39
Response to Solar Irradiance
1000 W/m2
Current increases with
increasing irradiance
750 W/m2
500 W/m2
Maximum power increases
with increasing irradiance
Maximum power voltage
changes little with irradiance
250 W/m2
Voc changes little
with irradiance
Voltage
 2012 Jim Dunlop Solar
Constant Temperature
Cells, Modules and Arrays: 5 - 40
Response to Solar Irradiance
Voc changes little with
irradiance above 200 W/m2
Isc increases with
increasing irradiance
0
200
400
600
Irradiance (W/m2)
 2012 Jim Dunlop Solar
800
1000
Constant Temperature
Cells, Modules and Arrays: 5 - 41
Response to Solar Irradiance
 The power and current output of a PV device are proportional to
the solar irradiance:
E2 I 2 P2
= =
E1 I1 P1
 Example: A PV module produces 200 watts maximum power at
1000 W/m2. Assuming constant temperature, the maximum power
output at an irradiance level of 600 W/m2 would be:
E2
600
P2 =
× P1 =
× 200 = 120 W
E1
1000
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 42
Response to Temperature
 For crystalline silicon PV devices, increasing cell temperature results in a
decrease in voltage and power, and a small increase in current.
Increasing temperature
reduces power output
Increasing
temperature
increases current
Increasing temperature
reduces voltage
T = 0°C
T = 25°C
T = 50°C
 2012 Jim Dunlop Solar
Voltage
Cells, Modules and Arrays: 5 - 43
Temperature-Rise Coefficient
 The temperature-rise coefficient relates the temperature of a
given PV array to the ambient air temperature and solar
irradiance:
Tcell =
Tamb + (CT − rise × E )
where
Tcell = cell temperature (C)
Tamb = ambient air temperature (C)
CT − rise = temperature-rise coefficient (C/kW/m 2 )
 At peak sun, the difference between PV array and ambient air
temperature can vary from 20 to 40°C, depending on the array
mounting system design.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 44
Temperature Coefficients
 Temperature coefficients relate the effects of changing PV cell
temperature on voltage, current and power.
 Percentage change coefficients are commonly used to translate voltage,
current and power from one temperature condition to another
temperature.
 For crystalline silicon PV, percentage change temperature coefficients
are approximately:



CV = -0.4%/°C (voltage decreases 1% for 2.5°C increase in temperature)
CI = +0.04%/°C (current increases 1% for 25°C increase in temperature)
CP = -0.45%/°C (power decreases 1% for 2.2°C increase in temperature)
 Since the temperature coefficient for current is an order of magnitude
less than for voltage or power, the effects of temperature on current are
not usually considered in systems design.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 45
Temperature Translation
Equations
Vtrans = Vref + [Vref × CV × (Tcell − Tref )]
Ptrans = Pref + [ Pref × CP × (Tcell − Tref )]
where
Vtrans = translated voltage at Tcell (V)
Vref = reference voltage at Tref (V)
Ptrans = translated power at Tcell (W)
Pref = reference power at Tref (W)
CV = voltage-temperature coefficient (% per C)
CP = power-temperature coefficient (% per C)
Tcell = cell temperature (C)
Tref = reference temperature (C)
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 46
Response to Temperature:
Example 1
 A 72-cell crystalline silicon PV module has a rated open-circuit
voltage of 44.4 V at 25°C, and a voltage-temperature coefficient of
-0.33 %/°C. What would the open-circuit voltage be at a cell
temperature of 60°C?
Vtrans = Vref + [Vref × CV × (Tcell − Tref )]
Vtrans = 44.4 V + [44.4 V × -0.0033/ C × (60-25)C]
Vtrans = 44.4 V - 5.19 V = 39.2 V
 If the same PV module operates at -10°C (35°C lower than the
reference temperature), the translated voltage is:
Vtrans = 44.4 V + [44.4 V × -0.0033/ C × (-10 - 25)C]
Vtrans = 44.4 V + 5.19 V = 49.6 V
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 47
Response to Temperature:
Example 2
 A crystalline silicon PV array has a power-temperature coefficient
of -0.45 %/°C and rated maximum power output of 50 kW at 25°C
and solar irradiance of 1000 W/m2. What would the array
maximum power be at a cell temperature of 50°C?
Ptrans = Pref + [ Pref × CP × (Tcell − Tref )]
Ptrans = 50 kW + [50 kW × -0.0045/ C × (50-25)C]
Ptrans = 50 kW - 5.6 kW = 44.4 kW
 If the same PV module operates at 0°C (25°C lower than the
reference temperature of 25°C), the translated power is:
Ptrans = 50 kW + [50 kW × -0.0045/ C × (0 - 25)C]
Ptrans = 50 kW + 5.6 kW = 55.6 kW
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 48
Building PV Arrays
 Series strings of PV
modules are connected in
parallel to build current and
power output.
Current (A)
 PV modules are connected
electrically in series to build
voltage output.
Voltage (V)
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 49
Monopole and Bipolar
PV Arrays
 Monopole PV arrays consist of two output circuit conductors.
 Bipolar PV arrays combine two monopole arrays with a center
tap.
Positive (+)
Negative (-)
PV Array
Monopole Array
 2012 Jim Dunlop Solar
Positive (+)
Center Tap
PV Array
Negative (-)
PV Array
Bipolar Array
Cells, Modules and Arrays: 5 - 50
Connecting Similar
PV Devices in Series
(+)
1
(-)
(+)
2
(-)
(+)
n
(-)
Vseries string = V1 + V2 ….. + Vn
Vseries string = V1 x n
Pos (+)
 2012 Jim Dunlop Solar
Neg (-)
Iseries string = I1 = I2 ….. = In (for similar
devices)
Cells, Modules and Arrays: 5 - 51
I-V Curves for
Similar PV Devices in Series
For similar PV devices in series:
Vseries = V1 + V2 ….. + Vn
Vseries = V1 x n
Current (A)
Iseries = I1 = I2 ….. = In
1 device
2 devices
in series
“n” devices
in series
Voltage (V)
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 52
Dissimilar PV Devices in
Series
 When dissimilar PV devices are connected in series, the voltages
still add, but the current is limited by the lowest current output
device in series.
 Not acceptable.
Pos (+)
A
(-)
(+)
B
Neg (-)
Vseries = VA + VB
Pos (+)
 2012 Jim Dunlop Solar
Iseries = IA < IB
Neg (-)
Cells, Modules and Arrays: 5 - 53
Connecting PV Devices
in Parallel
Pos (+)
(+)
(+)
(+)
1
2
n
(-)
(-)
(-)
Neg (-)
For PV devices in parallel:
Vparallel = V1 = V2 ….. = Vn (for similar devices)
Vparallel = (V1 + V2 … + Vn) / n
Iparallel = I1 + I2 ….. + In
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 54
I-V Curves for
Similar PV Devices in Parallel
For PV devices in parallel:
Current (A)
Devices 1+2
in parallel
Vparallel = V1 = V2 ….. = Vn (for similar
devices)
Vparallel = (V1 + V2 … + Vn) / n
Iparallel = I1 + I2 ….. + In
Device 1+2
independently
Voltage (V)
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 55
Connecting Dissimilar PV
Devices in Parallel
 When PV devices with the same voltage but with different current
output are connected in parallel, the individual currents add, and
the voltage is the average of devices.
A
Vparallel = (VA + VB) / 2
Iparallel = IA + IB
Neg (-)
Pos (+)
B
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 56
Connecting Dissimilar PV
Devices in Parallel
 Series strings of PV modules with similar voltage but having
different current output may be connected in parallel.
Current (A)
For dissimilar current PV
devices in parallel:
Vparallel = (V1 + V2 … + Vn) / n
Devices 1+2
in parallel
Iparallel = I1 + I2 ….. + In
Device 1
Device 2
Voltage (V)
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 57
Bypass Diodes
 Bypass diodes are connected in parallel with series strings of
cells to prevent cell overheating when cells or parts of an array
are shaded.
When cells are not shaded, the
bypass diode is reverse biased and
does not conduct current
When a cells is shaded, the bypass
diode is forward biased and conducts
current
Neg (-)
Pos (+)
Shaded cell
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 58
Current (A)
Without Bypass Diodes
Large power dissipation in module with
lower current (failing module)
Power produced by module with
higher current (healthy module)
operating current
Module 2
Module 1
0
<< Negative voltage (reverse bias)
 2012 Jim Dunlop Solar
Voltage (V)
Positive voltage (forward bias) >>
Cells, Modules and Arrays: 5 - 59
Current (A)
With Bypass Diodes
Low power dissipation in module with
lower current (failing module)
Power produced by module with
higher current (healthy module)
operating current
Module 2
Module 1
0
<< Negative voltage (reverse bias)
 2012 Jim Dunlop Solar
Voltage (V)
Positive voltage (forward bias) >>
Cells, Modules and Arrays: 5 - 60
Module Junction Box with
Bypass Diodes
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 61
PV Module Rating Conditions
 The electrical performance of PV
modules is rated at Standard Test
Conditions (STC):
Irradiance: 1,000 W/m2 , AM 1.5
 Cell temperature: 25°C

 2012 Jim Dunlop Solar
Source: SolarWorld USA
Cells, Modules and Arrays: 5 - 62
Other PV Module Ratings
 Standard Operating Conditions (SOC)
Irradiance: 1,000 W/m2
 Cell temperature: NOCT

 Nominal Operating Conditions (NOC)
Irradiance: 800 W/m2
 Cell temperature: NOCT

 Nominal Operating Cell Temperature (NOCT)
Irradiance: 800 W/m2
 Ambient Temp: 20°C
 PV Array: open-circuit
 Wind Speed: 1.0 m/s

 PVUSA Test Conditions (PTC):

1000 W/m², 45°C, 1 m/s
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 63
PV Module Rating Conditions
STC
SOC
PTC
NOC
Voltage
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 64
Approved Modules
 Certain listed PV modules have been approved as “eligible
equipment” for California incentive programs.

See: www.gosolarcalifornia.org
 These modules have had additional independent performance
tests for PTC ratings.
 Many other states refer to this list for eligible equipment for their
incentive programs.
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 65
Photovoltaic Module Standards
 Installation Requirements:
 National Electrical Code, NFPA 70
 Must be installed in accordance with manufacturer’s instructions
 Product Listing
 UL 1703: Standard for Safety for Flat-Plate Photovoltaic Modules and Panels
 Design Qualification (reliability testing)
 IEC 61215: Crystalline Silicon Terrestrial Photovoltaic (PV) Modules - Design
Qualification and Type Approval
 IEC 61646: Thin-Film Terrestrial Photovoltaic (PV) Modules - Design Qualification
and Type Approval
 Performance Measurement
 ASTM E1036: Standard Test Methods for Electrical Performance of Nonconcentrator Terrestrial Photovoltaic Modules and Arrays Using Reference Cells
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 66
PV Module Markings
 All PV modules must be marked
with the following information [NEC
690.51]:








Open-circuit voltage
Short-circuit current
Operating voltage
Operating current
Maximum power
Polarity of terminals
Maximum overcurrent device
rating
Maximum permissible system
voltage
 2012 Jim Dunlop Solar
Cells, Modules and Arrays: 5 - 67
Fire Classification
 PV modules may be evaluated for external fire exposure for
building roof covering materials.
 The fire class is identified in the individual Recognitions as class
A, B or C in accordance with UL's Roofing Materials and Systems
Directory.
 Modules not evaluated for fire exposure are identified as NR (Not
Rated), and not suitable for installation on buildings.
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PV Module Design Qualification
 PV modules attaining optional design qualification undergo
additional reliability testing that validates long-term warranties.
 The tests include:
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Thermal cycling tests
Humidity - freezing tests
Impact and shock tests
Immersion tests
Cyclic pressure, twisting, vibration and other mechanical loading tests
Wet/dry hi-pot, excessive and reverse current electrical tests
Other electrical and mechanical tests.
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Module Installation Instructions
 Listed PV modules must be installed in accordance with
instructions provided (shipped) with product.
 Includes safety information, working with PV modules during sun
hours (energized electrical equipment), mounting configurations,
and electrical wiring and grounding instructions.
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PV Module Safety
 Most manufacturer’s literature states that module installation
should be done by qualified, licensed electrical professionals.
 Safety precautions for installing PV modules include:
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Do not insert electrically conducting parts into the plugs or sockets.
Do not wear metallic jewelry while performing installation.
Do not fit solar modules and wiring with wet plugs and sockets. Tools and
working conditions must be dry.
Exercise extreme caution when carrying out work on wiring and use the
appropriate safety equipment (insulated tools/gloves, fall protection, etc.)
Do not use damaged modules. Do not dismantle modules. Do not remove
any part or label fitted by the manufacturer. Do not treat the rear of the
laminate with paint, adhesives or mark it using sharp objects.
Do not artificially concentrate sunlight on modules.
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Handling PV Modules
 Care in handling, transporting, storing and installing PV modules
includes the following:
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Leave modules in packaging until they are to be installed.
Carry modules with both hands, do not use connectors as a handle
Do not stand modules on hard ground or on their corners
Do not place modules on top of each other or stand on them
Do not mark or work on them with sharp objects
Keep all electrical contacts clean and dry
Do not install modules in high winds
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Module Selection Criteria
 The selection of PV modules for a given project may be based on
any number of factors, including:
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Module physical and electrical specifications
Manufacturer certification to quality standards (ISO 9000)
Module warranty and design qualification (IEC 61215/61216)
Customer satisfaction and field results
Company ownership and years in business
Costs and availability
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Summary
 Photovoltaic (PV) cells are semiconductor devices that produce
electrical output when exposed to sunlight.
 The current-voltage characteristic (I-V curve) is the basic
descriptor of PV device performance.
 The output of a PV device is dependent upon sunlight intensity,
temperature and electrical load.
 PV devices are connected in series to build voltage, and in
parallel to build current and power output.
 PV modules are installed in accordance with installation
instructions and local building codes.
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Questions and Discussion
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