BROKEN GLASS
No value at all, panel is recycled.
Moisture enters and affects PV cells, expanding the damaged glass surface. Only option is to recycle the panels.
ISOLATION ERROR
Depends on the level of the isolation error.
A PV isolation fault is usually an earth fault on the DC side (the PV panels side) of the system which is usually caused by moisture ingress or damage to the system or the panel.
– Low
– Medium
– High
DELAMINATION
Delamination of a PV panel is the detachment, even
if partially, of the encapsulant from the glass or the
backsheet.
Different types and levels:
– Bubbles inside modules.
– Low isolation resistance.
– Ribbon / busbar corrosion.
– Forming a continuous path between any part of the electrical circuit and the edge of the PV panel.
BACKSHEET CRACKS
Backsheet cracks is the degradation of the outermost
“layer” of a PV panel and occurs on different stages.
– Not visible yet, backsheet gets pours.
– Beginning of cracks – light impact.
– Full cracks around the cells.
– Backsheet disintegrates.
SNAIL TRAILS
Snail trails are discoloration of the PV panel, which
builds up over years of power production on the field.
Moister can enter through the back sheet and diffuse
to the cell surface.
Different levels:
– 1-3 cells affected.
– 4-6 cells affected.
– More than 6 cells with snail trails.
DUST BUILD-UP
Accumulation of dust on the surface of PV panel.
Reduces the glass cover transmittance and hence decreases the amount of solar irradiation reaching the cells.
CRACKED CELLS
They are triggered by mechanical and chemical environmental factors causing stress to the
panel during operation.
Further stress factors are geared to the thermal cycles of the cells involving contracting, expanding and flexing metal contacts, solder and wire interconnects.
POOR STRING CONNECTION
Failures due to improper installation and operating
stress are both avoidable.
Inadequate wire terminations, undersized conductors,
environmental conditions that are outside of the equipment rating, inadequate protection from surge voltage and inadequate protection from physical damage.
POTENTIAL INDUCED DEGRADATION
Potential induced degradation (PID) is a performance
degradation in crystalline PV panels.
Caused by so called stray currents. This effect may
cause power loss of up to 30 percent.
CHALKING
Polymer degradation in paints and coatings affecting
reliability and performance.
Backsheet chalking is a failure mode of field exposed PV panels and is observable as a white powder on the outer backsheet layer.
HOT SPOTS
When such a condition occurs, the affected group of cells is
forced into reverse bias and dissipates power, which can cause
local overheating with different levels.
– 1-3 cells affected.
– 4-6 cells affected.
– More than 6 cells with hot spots.
JUNCTION BOX
The junction box of PV panels fails in the field mainly
because of fault current passing through the Junction box.
The main failures of Junction boxes are:
– Burnt bypass diode.
– Burnt off junction box.
– Lost connection.
– Malfunction.
– Connection cable cut / broken.
MICRO CRACKS
Micro fractures, also known as micro cracksMicro fractures, also known as micro cracks
The silicon used in the PV cells is very thin and expands and contracts due to thermal cycling. During the day, the solar panels expand because of higher temperatures.
HOLES
Different types of holes.
Moisture enters and affects PV cells. Holes tend to expand and get bigger.
SCRATCHES
Damage or scratches will result in a reduction of efficiency.
The wrong cleaning tools and improper cleaning methods can scratch PV panels or make the glass cloudy.