PVe Troubleshooting

The most common errors

Causes of reduced performance and yield in PV generators

Suboptimal system configuration

Indicated by

Measurement of mismatch losses

Possible cause / remedy

Planning error / Reconfiguration

Improper string-to-inverter configuration

Indicated by

Feed-in power insufficient for the location and generator capacity

Possible cause / remedy

Planning errors / reconfiguration, replacement of inverters

Shading due to cast shadows

Indicated by

I-V curve with irregularities (“bumps”), peak power too low, check by visual inspection

Possible cause / remedy

Obstruction near the module (e.g. bird droppings) / Remove obstruction

Diffuse shading (may not be detectable with the naked eye!)

Indicated by

I-V curve appears “flattened”, peak power too low

Possible cause / remedy

Obstruction at a distance (increasing diffuse light component) / Remove obstruction

Corrosion at connectors and terminals

Indicated by

Excessive series resistance (Rs)

Possible cause / remedy

Material, design, or installation faults / Clean or replace

Cell encapsulation delamination

Indicated by

I-V curve appears “flattened”, peak power too low

Possible cause / remedy

Material or production faults / Replace

Resin blistering / Blister formation in resin

Indicated by

I-V curve appears “flattened”, peak power too low

Possible cause / remedy

Material fault / Replacement by the supplier

Loss of transparency of the cover material (glass, plastic, resin)

Indicated by

Visual inspection, peak power too low (see also diffuse shading)

Possible cause / remedy

Material fault / Replacement by the supplier

Yellowing/discoloration of the transparent encapsulation material (plastic, resin)

Indicated by

Visual inspection, peak power too low (see also diffuse shading)

Possible cause / remedy

Material fault / Replacement by the supplier

Moisture ingress into the laminate, causing secondary damage (e.g. corrosion, discoloration)

Indicated by

Optical check

Possible cause / remedy

Material, manufacturing defects / replacement by suppliers

Cell-level defects caused by micro-shunts (hot-spot effect)

Indicated by

I-V curve appears “flattened”, peak power too low

Possible cause / remedy

Material, manufacturing defects / replacement by suppliers

Module soiling (dust)

Indicated by

Visual check, similar to diffuse shading

Possible cause / remedy

High dust exposure (usually not an issue in Germany). Regularly check modules / Clean

Moss and algae growth on module surfaces, bird droppings

Indicated by

I-V curve with irregularities (“bumps”), peak power too low, check by visual inspection

Possible cause / remedy

Normal depending on site and region / Clean

Cover glass fracture causing secondary damage (e.g. corrosion, discoloration)

Indicated by

Optical check

Possible cause / remedy

Hail damage, installation faults, transport damage / Replace by supplier

Poor electrical connections within the module

Indicated by

Peak power too low, series resistance (Rs) above calculated value

Possible cause / remedy

Soldering errors, material defects, or corrosion / Replace by supplier

Bypass diode defective (short circuit)

Indicated by

Peak power of the string reduced by the power of one module

Possible cause / remedy

Overload, material defects / repair

Bypass diode incorrectly installed (reverse polarity)

Indicated by

Peak power of the string reduced by the power of one module

Possible cause / remedy

Installation fault / Repair

Missing bypass diode or defective diode (high impedance)

Indicated by

Shading of one module may significantly decrease string output

Possible cause / remedy

Design or installation faults / Repair

Verkabelung zu klein dimensioniert

Indicated by

Excessive series resistance (Rs)

Possible cause / remedy

Planning errors / cabling replacement

Damaged cable (e.g. fracture, corrosion)

Indicated by

Excessive series resistance (Rs)

Possible cause / remedy

Installation fault / Repair

Improper connector termination / Defective connector connection

Indicated by

Excessive series resistance (Rs)

Possible cause / remedy

Installation fault / Repair

Corrosion in screw or plug-type connectors

Indicated by

Excessive series resistance (Rs)

Possible cause / remedy

Installation fault / Clean and repair

Improper pre-sorting of modules by peak power (mixing high- and low-performing modules in one string)

Indicated by

Insufficient system peak power

Possible cause / remedy

Planning and assembly errors (match losses) / reassembly of modules after peak power measurement

Insufficient sorting of individual cells by power output in module production

Indicated by

Insufficient module peak power

Possible cause / remedy

Manufacturing fault / Price adjustment or replacement by supplier

Cell-to-cell short circuit within the module

Indicated by

Insufficient system peak power, open-circuit voltage (Uoc) too low, I-V curve characteristics

Possible cause / remedy

Manufacturing fault / Replace by supplier

Production tolerances in cell manufacturing

Indicated by

Peak power too low, I-V curve characteristics

Possible cause / remedy

Manufacturing fault / Price adjustment or replacement by supplier

PID – Potential Induced Degradation

Indicated by

Peak power too low, voltage too low, I-V curve characteristics

Possible cause / remedy

Design error, material fault / Rework or replacement