PVe Troubleshooting
The most common misfunctions and defects
Causes of reduced performance & lower yield of PV generators
System configuration not optimally selected
Recognizable by
measurement of match losses
Possible cause / remedy
planning errors / reconfiguration
Incorrect adjustment of strings to inverters
Recognizable by
Power fed in is too low for the location and power of the generator
Possible cause / remedy
Planning errors / reconfiguration, replacement of inverters
Shading with drop shadows
Recognizable by
I-U characteristic curve has "bumps", peak power too low, optical check
Possible cause / remedy
Obstacle in the immediate vicinity of the module (e.g. bird droppings) / Remove obstacle
Shading diffuse (possibly not visible to the naked eye!)
Recognizable by
I-V characteristic curve is "dented", peak power too low
Possible cause / remedy
Obstacle at some distance (high diffuse light component) / remove obstacle
Corrosion on plugs/terminals
Recognizable by
Internal series resistance Rs too high
Possible cause / remedy
Material, planning, assembly errors / Cleaning, replacement
Detachment of the cell embedding
Recognizable by
I-V characteristic curve is "dented", peak power too low
Possible cause / remedy
Material, manufacturing defects / exchange
Blistering in resin
Recognizable by
I-V characteristic curve is "dented", peak power too low
Possible cause / remedy
Material defects / replacement by supplier
Blinding of the transparent cover material (glass, plastic, resin)
Recognizable by
Optical control, peak power too low (see also diffuse shading)
Possible cause / remedy
Material defects / replacement by supplier
Discoloration of the transparent cover material (plastic, resin)
Recognizable by
Optical control, peak power too low (see also diffuse shading)
Possible cause / remedy
Material defects / replacement by supplier
Penetration of moisture between the laminate leads to other damages (corrosion, discoloration)
Recognizable by
Optical inspection
Possible cause / remedy
Material, manufacturing defects / replacement by suppliers
Errors in individual cells due to micro-shunts (hot spot effect)
Recognizable by
I-V characteristic curve is "dented", peak power too low
Possible cause / remedy
Material, manufacturing defects / replacement by suppliers
Contamination of the module by dust
Recognizable by
Visual inspection, such as diffuse shading
Possible cause / remedy
High dust load (usually not a problem in Germany). Check modules regularly / clean
Moss/algae growth on the module, bird droppings
Recognizable by
I-V characteristic curve has "bumps", peak power too low, visual inspection
Possible cause / remedy
Depending on region and location normal / Cleaning
Breakage of the cover glass, leading to other damage (corrosion, discoloration)
Recognizable by
Optical inspection
Possible cause / remedy
Hail damage, assembly error, transport damage / replacement by supplier
Poor electrical connections in the module
Recognizable by
Peak power too low, series internal resistance Rs higher than calculated
Possible cause / remedy
Soldering errors, material defects, corrosion / Replacement by supplier
Bypass diode defective (short circuit)
Recognizable by
Peak power of the string reduced by module power
Possible cause / remedy
Overload, material defect / repair
Bypass diode mounted incorrectly
Recognizable by
Peak power of the string reduced by module power
Possible cause / remedy
Assembly error / repair
No bypass diode installed or diode defective (high resistance)
Recognizable by
Shading a module can dramatically reduce the performance of the string
Possible cause / remedy
Planning, assembly errors / repairs
Cabling too small
Recognizable by
Internal series resistance Rs too high
Possible cause / remedy
Planning errors / replacement of the cabling
Cable defective (e.g. breakage, corrosion)
Recognizable by
Internal series resistance Rs too high
Possible cause / remedy
Assembly error / repair
Poor connection of connectors
Recognizable by
Internal series resistance Rs too high
Possible cause / remedy
Assembly error / repair
Corrosion in screw or connectors
Recognizable by
Internal series resistance Rs too high
Possible cause / remedy
Assembly errors / cleaning, repair
Poor pre-selection of modules according to peak performance (good/bad modules each in a string)
Recognizable by
Peak power of the system too low
Possible cause / remedy
Planning and assembly errors (match losses) / reassembly of modules after peak power measurement
Inadequate pre-selection of single cells according to performance during module production
Recognizable by
Peak power of the module too low
Possible cause / remedy
Manufacturing defects / price reduction, replacement by supplier
Short circuit between individual cells in the module
Recognizable by
Peak power of the system too low, Open circuit voltage Uoc too low, Characteristic curve
Possible cause / remedy
Manufacturing defects / replacement by supplier
Manufacturing tolerances in cell production
Recognizable by
Peak power too low, characteristic curve
Possible cause / remedy
Manufacturing defects / price reduction, replacement by supplier
PID – Potential-Induced Degradation
Recognizable by
Peak power too low, voltage too low, characteristic curve
Possible cause / remedy
Planning errors, material defects / repair, replacement
