IEA PVPS Task 13: ST 3.3 IR and EL in the Field

Anne Andersson

Svenska Task13

Task 13 ST3.3 will provide Guidelines

• overview of different methods to collect EL and IR images in the field

• Input in standardization of IR and EL images in the field

• analyze the available field data for trends to identify the most common failures using visual inspection and whether these are correlated with climate or system type

Why Guidelines ?

• Failure not detected

• Improving the image quality

• Making images more comparable

• Different opinions and recommendations

• Harmonizing evaluation methods

• Classification of visible abnormalities

Content of the guidelines

1.Normative references

2.Overview of different types of IR/EL cameras

3.Requirements for cameras and operation conditions

4.Recommendations for the inspection procedure

5.Recommendations for failure classification, evaluation and reporting

6.Examples of abnormalities

Normative references• Few standards at the moment, but several Technical Specifications (NWIP

of IEC TC82 WG2) with focus on IR and EL are in progress • IEC 62446: Grid connected photovoltaic systems – Minimum requirements

for system documentation, commissioning tests and inspection • Annex D (informative): PV array infrared camera inspection procedure • IEC 62446-3 TS: Photovoltaic (PV) systems - Requirements for testing,

documentation and maintenance Part 3: Outdoor infrared thermography of photovoltaic modules and plants

• DIN 54190: Non-destructive testing – Thermographic testing – part 1, 2 and 3

• DIN 54191: Non-destructive testing – Thermographic testing of electric installations

• IEA-PVPS Task13-01:2014 report Review of Failures of Photovoltaic Modules

• IEC 60904-12 TS: Photovoltaic devices - Part 12: Infrared thermography ofphotovoltaic modules

EL electroluminiscence

• EL done in dark at Isc (ampere source is needed)

• EL is the Si that glows(like LED) at bandgap =1100 nm not visible wavelengths

• Silicon array camera filtered can see EL

• Better with InGaAs

UV fluorescence in field demonstrated in Bolzano at Task 13 meeting

POWER NEEDED

IR Infrared

• IR picture Temperature differences, heatingeffects, either lack of current(low T) or short cirquit (high T) and all normal in between

• Emissivity Eglass = 0,95 perpendicular to the module plane but the emissivity decreases with the angle of view, so at around 45° the emissivity will be around = 0,8 and at 60° it can be around = 0,75 or lower

• E+R=100% if T=0 - R will have importance when E drops

Two different levels of inspectionsIEC 62446-3 TS

a. A simplified thermographic inspection, for example during the commissioning of systems, with reduced requirements for the qualification of personnel. This is for a limited inspection to verify that the PV modules and BOS components are functioning. Authoritative conclusions regarding module quality are not possible. To validate the abnormalities, please refer to the examples in the Annex Cb. A detailed thermographic inspection and analysis, which may include all thermal structures, which differ from the examples in Annex C, and for periodic inspections according to IEC 62446-series. An authorized expert for PV plants and thermography experts, with qualification equal to level 2 electro thermography according to ISO 9712, shall to be involved.

Qualification of personnel

The testing personnel shall have sufficient knowledge in electrical installations, PV plants and also regarding thermography including the analysis of the thermographic findings in electrical systems:

1. sufficient knowledge to be able to work in electrical installations has to be proven, 2. sufficient knowledge to document PV power plant related findings in accordance to requirements stated in relevant standards (e.g. IEC 62446-series). 3. knowledge and skill in electro thermography has to be assured by the proof of a qualification and a certification.

A certificate according to ISO 9712 can serve as confirmation.

!!First!!Visual inspection & documentation

• Things like bird droplets, strong soiling, burn spots on modules or findings on Balance of System (BOS) components shall be documented by photos and location prior the thermographic inspection. Either those findings should be resolved e.g. by cleaning, especially during comissioning, or conduct the thermography inspection without cleaning, e.g. for a root-cause analysis for a poor performing powerplant.

• Documentation soiling, irradiation, temperature ambient and modules, wind, clouds, string current

IEC stage(CD)62446-3 IEC:2016NON-DESTRUCTIVE TESTING INFRARED THERMOGRAPHY OF PHOTOVOLTAIC

MODULES AND PLANTS FOR INSPECTION

• Both photo camera and IR camera are recommended, in order to ensure sufficient resolution

• Calibrated camera is recommended• Irradiation 600 W/m2• Change in Irr < 10%Irr/minute• Octa value – cloud coverage < 2/8• Cumulus shall be avoided • Cirrus can be ok• Wait 15 minutes after delta Irr changed more than 10%• Angle as close to normal as possible• Speed on drone < 3m/s • Wind - always some convection due to T- differences• 4 year inspection cycle on PV-systems is suggested due to electrical

component

Angle of view relative to surface normal

• shall be maintained between 0 °and 40 ° for glass and between 0 ° and 45 ° for polymer back sheets, optimally close to normal.

• close to 0 ° from module normal, it will be necessary to account for reflections from the camera and operator;

• far from normal outdoors, reflections of buildings, other modules, and landscape may become greater

Classification

• Class 1: No abnormalities• Class 2: Thermal abnormality that may cause a

problem in the future and can be compared with sample IR images for further decisions

• Class 3: Safety relevant thermal abnormality that causes a direct safety problem. Thus the PV plant must be disconnected and the problem has to be solved immediately.

IR minimum camera requirements

• Temperature range (-20°C – 120°C) • Recommended resolution > 320 x 240 pixel • Adjustable emissivity• Maximum measurement error (<3K) • Calibration certificate• User friendly documentation• Camera sensitive 7 um – 13 um• Cameras sensitive under 4 um - consider glass is

transparent under that wavelength• Separate photo camera are recommended

At SP we have tried with 3 different cameras

• FLIR i5

• FLIR T420

• Seek

Seek FLIR i5 FLIR T400Pris, kr 2 500 11500 89500Temp, C' -40 - +330 -20- + 250 -20 - +650

T °C ? 0,1 0,045pixlar 206x156 100x100 320x240frekvens ? 9 Hz 60 Hzminsta avstånd, cm 20 60 40längsta avstånd, cm 300synfält ° 20 21 25x19IP-klass - 43 45Emissivity - 0,1 - 1 0,1 - 1

Comparison 2 cameras

Seek and FLIR high res

FLIR i5 and Seek

FLIR i5 and Seek

VARBERG 2.7 MW PÅ JORDBRUKSMARK

HOT SPOT ALSO ON A CLOUDY DAY

APLAKULLA, BORÅS, SEPTEMBER 2016

BUA KYRKA CIRRUS MOLN

TACKSOLISAR!!