TRAINING COURSE
BASIC PRINCIPLES FOR DESIGN AND
CONSTRUCTION OF PHOTOVOLTAIC PLANTS
Ing. Salvatore Castello
ENEA - Renewable Energy Technical Unit - Photovoltaic Lab
Summary
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Criteria for selecting PV modules
Strings and PV generator
Supporting structures
Fire prevention
Power conditioning unit
The connection to the grid
Design documentation
GRID CONNCTED PLANT
PV GENERATOR
POWER CONDITIONING UNIT
UTILITY
GRID
modules
string
String
box
DC side
protections
DC/AC
inverter
Grid
Interface
protection
Production
counter
string
USER LOADS
Energy
to/from the
grid
THE CHOICHE OF THE PV MODULES
• Most suitable technology for PVPS applications
• Electrical and mechanical features
• Specific requirements (BIPV)
• Quality of modules
• Compliance with norms
• Terms of warranty
• Recovery and recycling possibility
TECHNOLOGY OPTIONS
CRISTALLINE
• Mature and reliable
technology (useful life tested
in the field for 30 years)
• Good values ​of efficiency (1419%)
• Appearance is not entirely
satisfactory
THIN FILMS
• Useful life not tested yet in real
operating condition
• Degradation in the first days of
exposure
• Lower efficiency (7-13%)
• More suitable in architecture
• Greater yield
TECNOLOGIES AND YIELD
a-Si
C-Si
Temperature effect
Dp = - 4,6% / 10 °C
Dp = - 2,1% / 10 °C
Dp = - 2,5% / 10 °C
Dp = - 3,66% / 10 °C
c-Si
a-Si
CdTe
CIS
Spectral response
Low irradiance
Artificial or
diffused light
solar light
a-Si
C-Si
MODULE REQUIREMENTS
In some application (BIPV) modules should be chosen in order to meet
the requirements:
• Functional
• Waterproofing
• Thermal insulation
• Mechanical safety
• Transparency
• Architectural
• particular dimensions
• Colors
• Aesthetic appearance and forms
• Electrical
• must be able to withstand a maximum permissible voltage
MECHANICAL SAFETY IN BUILDINGS
Reference standards specify the
glass typologies for each part of
the building
Glass roofs
• Stratified glasses
• tempered and laminated
(greater strength against
thermal stress)
Facades
• tempered and laminated
(in case of fall off risk:
below 1 meter from the
floor level)
MODULE WARRANTY
The manufacturer provide:
• Product warranty: 10 years against manufacturing defects
• Performance warranty :
• P (10 years)> 90% * Pi
• P (25 years)> 80% * Pi
It is advisable that the year of fabrication is clearly documented (running of
warranty period)
Excluded from warranty damages and failures resulting from misuse
MODULE DEGRADATION RATE
ENEA has carried out a measurement
campaign to evaluate the performance
degradation of PV modules
Sample under test: 80 PV modules
installed in 1980
Measurements over the years: IV curve of
each module
Efficiency degradation: 0.4% / year
(constant over the years)
MODULE DEGRADATION RATE
Results of tests conducted by laboratories worldwide
Dates of installation prior and after to the year 2000
The crossbars denote the mean for each category
The diamond represent the 95% confidence interval
PHYSICAL DEGRADATION OF MODULES
Defects observed during 33 years
Detachment of Tedlar
Tedlar cracking
collecting grid oxidation
The defects found did not result in further efficiency degradation compared to the
natural one (0.4% / year)
This experience shows that the life time of the modules (glass-tedlar) can be
estimated superore to 30 years.
Plant efficiency (%)
10
8
6
4
2
0
5
10
15
Years
Fault
Inverter replacement
Fault (inverter or PV
generator)
TYPICAL SEQUENCE OF EVENTS
14
12
0
20
25
30
35
MODULE QUALITY CONTROL
• To ensure a long time outdoor operation, PV modules must have suitable
electrical, thermal and mechanical characteristics
• Such features are verified by tests described in the norms
• IEC 61215
C-Si
• IEC 61646
thin film
• IEC 62108
PV concentration
• Further test are foreseen in IEC 61730 part 1 and 2
• Allow to assess the safety requirements in the construction and
qualification phases
• to check the insulation levels of the modules: Class I and II
• to affix the CE marking (compliance with this standard implies conformity
to the essential requirements of the EU Directive for Low Voltage
appliances)
COMPLIANCE WITH THE NORMS
Is documented by:
• Type approval Certificate
• is issued by an Accredited Laboratory
• is accompanied by a Test report
• Conformity Certificate
• is issued by a Certification body, as a result of tests performed by an
Accredited laboratory
• is accompanied by a test report
• Test report
• is issued by an Accredited laboratory, following tests according to the
relevant standards
• contains the results of measured characteristics and details of defects
TYPE APPROVAL CERTIFICATE
Minimum information contained
• Name and Accreditation number of the
Laboratory
• Date and number of the test
• Name and address of the module
manufacturer
• Model and acronym of the module
• Main features of the module:
technology, number and size of the
cells, rated power
• Adopted rules to test the modules
(indication of not performed tests)
• Time validity
ACCREDITED LABORATORY


must be accredited by organizations belonging to the EA (European
Accreditation Agreement) for specific tests listed in the norms or
have established mutual recognition agreements in the framework of EA
or ILAC (International Laboratory Accreditation Cooperation)
CONFORMITY CERTIFICATE
Minimum information contained
– Name of certification body
– Date and number of the Certificate
– Name and address of PV module
manufacturer
– Module model and acronym
– Main features of the module
– Adopted rules to test the modules
– References of the Test Report
– Name of the testing laboratory
– Indication of the control in the
factory (factory inspection)
– Time validity
CERTIFICATION BODIES
Must be:
1) accredited by organizations
belonging to EA (European
Accreditation Agreement) and
2) member of the IECEE (IEC for
Conformity Testing and
Certification of Electrotechnical
Equipment) within photovoltaic
sector.
List at:
http://www.iecee.org/pv/html/
pvcntris.htm
CERTIFICATION OF NON STANDARD MODULES
• if are not commercially available certified products that could
realize the type of integration designed, could be used PV
modules not certified according IEC standards
• In this case the manufacturer typically provide a:
• Declaration about the capability of the product to pass the
tests required by the norms
• Conformity Certificate of standard modules fabricated with the
same process phases
FACTORY INSPECTION CERTIFICATE
• Is a further demonstration of the module quality
• is issued by a Certification body as a result of periodic checks conducted
at the factory, to verify that remain constant over time
• manufacturing process and
• materials used
• may be
• included in the Certificate of Conformity (single certificate) or
• recall the Certificate of Conformity
FACTORY INSPECTION ATTESTATION
• Is aimed at identifying the origin of the
product
• issued by a Certification body
• contains the following information:
• indication of the of the process phases
that are carried out
• identification code and address of the
site
• the identification code of the site and
the logo of the Certification body
must be shown on the label of the
module
MODULE CERTIFICATION
• Original Equipment Manufacturer Certificate
• is issued by a Certification body if the company that label the module is
not the manufacturer
• indicates the name and address of the manufacturer and the company
that markets the module
• is accompanied by a test report
• Quality system within operate the manufacturers is evidenced by the
certification on:
• Quality management system (ISO 9001:2008)
• Management system of health and safety at work (OHSAS 18001)
• Environmental Management System (ISO 14001)
RECOVERY AND RECYCLING OF PV MODULES
• Each module producer shall adhere to a Consortium that guarantees the
collection and recycling of the modules at the end of life.
• Producer: Manufacturer / Importer / Distributor under its own brand
• Consortium: Subject supported by one or more Producers that on
behalf of their members:
• operates in compliance with the “National environmental code“
for the Electrical and Electronic Equipment category
CONSORTIUM REQUIREMENTS
• Must ensure all phases of the life cycle of the modules
• Collect the module from the installation site
• transport to a storage area
• Recover the materials at the recycling plant
• Reporting on
• amount collected and sent for recycling
• quantity and quality of recovered materials;
• Absolve the Producer from possible liability forms resulting from
violations of the rules
• Dispose of appropriate (and authorized)
• treatment and recycling plants
• collection and transport network
• storage areas for the delivery of modules to the recycling plants
CONSORTIUM REQUIREMENTS
• Must operates on modules
• removed from plants
• from production waste
• broken during transport or installation
• Achieve the traceability in order to bring the single module to
• the manufacturer or importer and
• to the plant in which was installed
• activates a financial instrument
• fed for at least 2/3 by modules producers
RECOVERY OF MODULE MATERIALS
Collected modules
 2011
1.500 ton. (23 MW)
 2012
6.000 ton. (90 MW)
Typical methods for material recovery
Si-C
CdTe
• Separation of the silicon:
• Cd and Te separated by fragments
thermal decomposition of the
of modules using dilute solution of
EVA in gas atmosphere of
H2SO4
nitrogenous
• The silicon wafers may be used
for the fabrication of new
modules
• These products can be reused if
treated with hydrogen peroxide
• Separation coefficient = 99%
MODULE CERTIFICATION (IEC 61215)
• Describes the requirements for the design qualification and type approval of
terrestrial photovoltaic modules suitable for long-term outdoor operation
• Visual inspection for defect detection
• misalignment or contact between cells
• broken cells
• discoloration
• air bubbles
• Measurements
• Pmax at STC characteristic I-V
• Pnom low Irr. (<200 W/m2)
• temperature coefficientsof Isc, Voc and Pm
• NOCT (Irr. 800 W/m2, T = 20 ° C)
MODULE TEST
TESTS
• insulation resistance
> 40 MW (Vtest=1.000V + 2 Vmax sys)
• immersion in water
insulation measurement
• Exposure
> 60h to 1 kW/m2
• Partial shadowing exposures
of 1 has 1000 W/m2
• UV exposure
> 15h to 1 kW/m2
• thermal cycles
200 from -40 ° C to +85 ° C
• diode thermal cycles
1h Isc = T = 75 ° C
• humidity exposure
1000 h to +85 ° C and 85% RH
• connectors resistance
stress simulating screw tightening operations
• mechanical load:
uniform load simulating wind speed 130 km/h
• Hail resistance
balls of ice 25 mm shoot 23 m/s in different
points of module
IEC 61730-1
• describes the construction requirements of PV modules in order to
provide safe electrical and mechanical operation
• Module application classes
• Class A
• general access,
• hazardous voltage, current and power
• double /reinforced insulation
• Class B
• Restricted access,
• hazardous voltage, current and power
• basic insulation only
• Class C
• general access
• limited voltage, current and power
IEC 61730-1
Construction and property requirements
• Metal parts (resistance to corrosion)
• Polymer Material for
• enclosure of live parts
• support live parts
• electrical barrier or pottant
• Encapsulants
• Frames
• Wiring and current-carrying parts
• Output Wiring Connectors
• Junction Boxes
• Creepage and clearance distances
• Mechanical securement
IEC 61730-2
IEC 61215
TEST PROCEDURES
IEC 61730-2
IEC 61215
IEC 60554
IEC 61730-2 and 61215
DIELECTRIC WITHSTAND TEST
IEC 61730
• Application class A:
Vtest = 2.000 V + 4 Vmax sys
• Application class B:
Vtest = 1.000 V + 2 Vmax sys
• Application class C:
Vtest = 500 V
FIRE TEST
Burning brand Test
Spread-of-Flame Test
Conditions of acceptance
At no time during the spread-offlame or burning-brand tests shall
any portion of the module be blown
off or fall off the test deck in the
form of flaming or glowing brands.
FIRE TEST
Fire test performed: is documented in the Confomity Certificate
ACCEPTANCE TESTS
in order to verify the compliance of modules to design specifications,
even before their installation, are carried out factory tests :
• visual inspection aimed to highlight any macroscopic defects
• electroluminescence test to detect any possible fractures of cells
(with an infrared camera when cells are crossed by a current:
damaged cells appear dark)
• Measure of the IV curve and Pnom, after sun simulator calibration
(with reference module previously calibrated by a Accredited
laboratory)
STANDARD DEVELOPMENTS FOR BIPV
• The standard distinguishes among
• modules like glass
• accessible or not from inside the building
• on roofs or facades
• with polymer sheets or Tedlar
• on metal foil
• on other materials (tiles, roofing elements)
• Defines the essential requirements relating to building aspects:
• Protection from weather conditions
• Mechanical resistance and stability
• Safety in case of fire
• safety in use
• Protection against noise
• energy saving
MECHANICAL RESISTANCE AND STABILITY
• Double glass module
• The increase in temperature of glass with PV cells inside
compared to normal glasses affects the structural requirements
(mechanical load and stiffness of the laminate must be verified
75 °C)
• Components for roofs
• test load of snow and hail: IEC 61215
• Test of resistance to lifting: required subdivision into classes
(wide variety of types, shapes and sizes)
Mechanical fixed
elastically fixed
PROTECTION FROM WEATHER CONDITIONS
WATERPROOFING Test
• characterizes the degree of
penetration of rain with different
• rain intensity
• Roof pitch
• Wind speed and climate zone
• Is assessed through the presence
(and amount) on the back of the
module
• Humidity
• Drops of water
• Infiltration of water
THANK YOU FOR YOUR
KIND ATTENTION
for information:
salvatore.castello@enea.it