Message Board Thread - "Solar panels"

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Solar panels EnjoyEnergy 6/8/2011
I have been asked to check solar panels of which the owner thinks they do not function well. I said I will do the check-up but to be honest I have never done this before. I own a E60. Can anybody out there tell me if this camera (E60) can do the job and how to handle, or locate me to a place on internet or book where this info can be get.

Anybody how can/will help me out here, thanks a lot in advance.
 
Re:Solar panels Gary Orlove 6/8/2011
The E60 is perfectly adequate to do this job. What type of solar panels are they?

Converting light to electricity?
or
Converting light to heat a fluid?

What specific problems are you trying to find?
 
Re:Solar panels EnjoyEnergy 6/9/2011
Gary Orlove wrote:
is perfectly adequate to do this job. What type of solar panels are they?

Converting light to electricity?
or
Converting light to heat a fluid?

What specific problems are you trying to find?
Hello Gary,

Thanks for your quick reply. It's about converting light to electricity. The owner concludes that the output is far less than expected. The solar system (7 x 180wp) is connected to a single converter. From the outside (top view) I can not see any dirt or so. So it has to be a broken or a bad weld or a small burst or ....!

How to start, is it necessary to disassemble the panels. If you can give some advice that would be absolutely great
 
Re:Solar panels EnjoyEnergy 6/9/2011
Hello Gary,

Thanks for your quick reply. It's about converting light to electricity. The owner concludes that the output is far less than expected. The solar system (7 x 180wp) is connected to a single converter. From the outside (top view) I can not see any dirt or so. So it has to be a broken or a bad weld or a small burst or ....!

How to start, is it necessary to disassemble the panels. If you can give some advice that would be absolutely great
 
Re:Solar panels dandersen 6/10/2011
Do you need a mid wave camera to see inside the panel?
 
Re:Solar panels Wieslaw 6/10/2011
Do not know if it'd be usable : Google found for me http://www.solarfuxx.de/pdf/defektanalyse-photovoltaik-anlagen.pdf , there are some informative pictures - language shouldn't be obstacle.. Hope it'd be usable (personally, I do not have any expieriences with photovoltaic, sorry)
 
Re:Solar panels JKEngineer 6/11/2011
Here's a Google translation of the text in the pdf identified by Wieslaw. I can't post it as a doc attachment, so I have pasted the text belwo.
Jack
Jack M. Kleinfeld, P.E.
Kleinfeld Technical Services, Inc.
Infrared Thermography, Finite Element Analysis, Process Engineering

NY

718-884-6644
866-884-6644 toll free
212-214-0919 fax and voice mail
Skype: JKEngineer

JKEngineer@aol.com or JKEngineer@KleinfeldTechnical.com
come see what we can do for you: http://www.KleinfeldTechnical.com

Bavarian Center for Applied Energy Research
Defect analysis
Photovoltaic modules using
Infrared thermography
4. Workshop "PV module technology", 29-30. Nov. 2007, TÜV Rheinland, Cologne
Ulrike Jahn, Claudia Buerhop, Ulrich Hoyer
Overview
1. Basic Physics
2. IR-defect analysis
3. IR measurements of PV components
Motivation
IR measurements for the error analysis of modules:
• non-contact and non-destructive testing
in the laboratory and in the field;
• Rapid detection of the correct operation
after installation;
• Module for detection of defects and degradation
of aged photovoltaic modules.
1. Basic Physics
Emissivity 0 <ε <1
indicates how much the emission of a real
The body of a black body is different.
ε = f (wavelength, temperature, material, surface)
Thermal equilibrium ε + τ + ρ = 1
ε = emissivity
τ = transmittance
ρ = reflectance
Values for the practice:
(At 8 micron wavelength)
PV: + Glass
- Metal frame
1. Basic Physics
ε = 0.85
Metal <0.1
Plastic ~ 0.92
Glass 0.85
Material ε
Glass ε (λ) = constant for λ = 8-12μm
ε (Temp) = constant for DT <100K
1. Basic Physics
"Optical window" for the practice
(1 km air distance)
Source: Sutor, Bischoff, Technical
University of Ilmenau, 2004.
1. Basic Physics
Angle dependence of emissivity
Anisotropy of the emissivity
with conductors and insulators
- Black body
No dependence
- Dielectric (glass)
cosine α
- Conductor (aluminum)
strong dependence
Source: Sutor, Bischoff, thermo-
Analysis, Technical University
Ilmenau, 2004.
1. Basic Physics
Emissivity as a function of wavelength for material groups
Area bolometer
Source: testo, guide to infrared technology, 2005.
2. IR-defect analysis
Type I Type II
Thermal sensitivity 0.1 K 0.01 K
Full frame rate 30 / s 145 / s
76 000 110 000 pixels
Bolometer detector CMT
(Uncooled) (cooled)
Working range 8 - 14 microns 1.9 to 5.6 microns
2. Defect analysis
• encapsulation material: glass, Tedlar, bypass diode
• Liability: Glass - film cell - Film
• Cell / module connector
• solar cell
• Humidity
Glass
Encapsulation
Solar cells
Back Sheet
Junction
box
Edge
sealent
Frame
2. Defect analysis
IR measurements
of PV modules:
- After production
- During commissioning
- By age
PV module (2005) with "patchwork" pattern
AT = 10 ° C
2. Defect analysis
No-load short-circuit load
Outdoor measurement: when> 700 W/m2
• cracks in the wafer
• Metallization
• broken cell
3. Hot Spot - crack in solar cell
Lock-in IR measurement
3. Contact finger breaks
156mm
Frequency: 4Hz
Measuring time: 5000 periods
Bias: 6A
IR measurement: Topography
Frequency: 4Hz
Measuring time: 5000 periods
Bias: 6A
3. Hot Spot - cell defects
PV systems with polycrystalline modules (2004):
Hot Spot: DT> 40 ° C
Source: BEC Engineering / Solar forge.
3. Hot Spots
Internal resistance increases: +120%
Rating and FF decreases the module: -12%
Ppk [W] 141 123
Rs [Ω] 1.8 4.0
Upmax [V] 32 30
Ipmax [A] 4.4 4.1
Voc [V] 44 44
Isc [A] 5.0 4.9
Hot Spot
Module
Reference
Module
3. Cell rupture
Above:
- Broken glass
- No cell rupture
Below:
- Broken glass
- Cell fraction
3. Cell rupture
0
0,5
1
1,5
2
2,5
3
0 5 10 15 20
Voltage [V]
Current [A]
Reference module
Faulty module
GI = 781 W/m2 tmod = 41.2 ° C FF = 0.42
3. Loss of adhesion
Shorted module with delamination of a cell
Source: Quintana et. al., 29th IEEE, 2002.
DT (cell)> 30 ° C
Short circuit of 18 cells
• increased temperature
• reduced stress
• reduced power
3. Defective bypass diode
measured under load
Short circuit
Last
Short-
Last connection
AT = 7 ° C
3. Defective bypass diode
Datasheet (STC) 160 W Isc = 5.1 A Voc = 44 V
Measurement at STC 51 W = 4.9 A Isc Voc = 15 V 1 / 3 active
0
1
2
3
4
5
6
0 10 20 30 40 50
Voltage [V]
Current [A]
Intact module
Faulty module
Erlangen school
IR images with MIDAS IR camera at 8 microns, 320x240 pixels
62 ° C
55 ° C • Outlets
• Elevation + Cable
• Defective Substring
• Single cell defects
3. Defective Substring
measured under illumination
Defective lead-out train between two laminates
3. Faulty connector
August 2007
3. Defective Substring
Ppk [W] 128 183
Hi [W/m2] 890 915
Upmax [V] 26.9 37.4
Ipmax [A] 4.1 4.3
Voc [V] 34.2 46.7
Isc [A] 4:55 4.63
Reference module
Defect
Module
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
0 5 10 15 20 25 30 35 40 45 50
Voltage [V]
Current [A]
Defective module
Reference module
Open Circuit Voltage: -27%
Power of the shorted module: - 30%
Summary
• IR striking modules (including cell plans) are not always
electrically relevant.
• Hot spots:
- Parallel Resistance: shunts in the emitter, moisture entry
- Series resistance: Fasteners, cell plans
• Substringausfall means voltage drop (UOC):
readily detectable by IR.
• Hot cells resulting from cell-mismatch (patchwork).
Conclusions
• IR measurements are suitable for the effective
Detection of defects in modules and
are well correlated with electrical measurements.
• IR detected greater power losses (> 20%),
often with FF losses and the increase
the series resistance are connected.
• Further studies on field aged
Modules must be conducted to the
Degradation mechanisms to understand better.
Thank you for your attention!


 
Re:Solar panels EnjoyEnergy 6/11/2011
dandersen wrote:
need a mid wave camera to see inside the panel?
Hello Wieslaw and Jack,
I would like to thank you both sincerely for your time and effort in helping me getting forward. Happily I do understand both german and english to a certain extend. So combining both of your contributions gives me a good idea of the workshop of the PV module technology. And for Danderson, as far as I know it is not needed to use a mid wave camera for outdoor inspection of solar panels. But if this is not correct please let me know. If any one can inform me about other practical does and donts I hope you feel free to tell me.
 
Re:Solar panels Christiane 6/30/2011
Hi,

you don't need a midwave camera for this type of work. As you understand some German take a look at this article http://www.ep-photovoltaik.de/pv-2011-01-32-35.pdf?eID=tx_mspdamlinks&dlid=66985&hash=711225a58373e566acfdc219b347469a or it's adaption to a FLIR technical note (in English): http://support.flir.com/appstories/AppStories/Electrical&Mechanical/Testing_solar_panels_EN.pdf .FLIR has also other technical notes on the topic, e.g. http://www.flir.com/uploadedFiles/Thermography/MMC/Brochures/T820260/T820260_EN.pdf .

Regarding the camera: the bigger the detector and the better the spatial resolution, the easier to do the inspection. But also with smaller cameras you can detect faults, however, it will take you much longer to inspect the panels as you have to be close and cannot scan bigger areas at once.

Good luck!
 


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