11 Most Common Solar Panel Defects

Written by Tony Chang

November 12, 2020

11 Most Common Solar Panel Defects

Solar modules are designed to produce energy for 25 years or more and help you cut energy bills to your homes and businesses.

Despite the need for a long-lasting, reliable solar installation, we still see many solar panel brands continue to race to the bottom to compete on price.

As some brands cut corners on product quality to remain price-competitive, solar panels start to fail in the field before their expected lifetime is up.

Here are 11 of the most common solar panel defects to watch out for in a solar installation, and how WINAICO works to prevent them from happening to your sites.

Hot Spots Speed up the Degradation of Solar Cells

Solar cells are designed to generate an electric current when the sunlight shines upon them.

When the current flows through the solar cell strings within panels, the resistance in cells converts the current into heat losses.

Any imperfection in solar cells, such as cracks, poorly soldered joints, and mismatches, lead to higher resistance and become hot spots in the long run.

The long term effects of hot spots include burnt marks that degrade solar cells and backsheets and may eventually lead to fires if left unchecked.

solar panel hot spot
Hot spots caused by defective solar cells can lead to a fire.

To eliminate hot spots in the field, WINAICO uses automated production processes to screen out imperfect solar cells before stringing them together.

This makes sure broken cells and poorly soldered ribbons do not ship out from WINAICO.

Microcracks on Solar Cells Reduce Energy Generation

The advancement in semiconductor processing has led to wafer-thin solar cells at around 170 μm in thickness, about twice the diameter of a human hair.

This led to extremely brittle solar cells prone to crack from any forceful impact.

When microcracks form in a solar panel, the affected solar cells will have trouble conducting electric currents, which lead to poor energy production and hot spots.

solar panel microcracks
EL picture of microcracks on solar panels due to poor handling practices.

WINAICO includes a stage of EL inspection, which acts like an X-ray for panels, to make sure no microcracks are introduced during solar module production.

You can bet our expert solar installer partners take exceptional care in transporting and handling solar panels to create a perfect install every time.

Broken Glass Makes Solar Cells More Susceptible to Weather Damages

The front glass panel of a solar module represents the first line of defence against the weather elements, like rain, dust, hail, and the occasional stray golf ball.

An ideal glass should be strong enough to withstand reasonable stresses like hailstones and golf balls while allowing sunlight to be absorbed by solar cells.

If an understrength glass is broken in, not only the light absorbed by the panel will diminish, foreign elements such as water and dust can go under the glass to shade solar cells and impact energy output.

broken glass solar panel
Broken glass makes solar panels more prone to future weather damages.

WINAICO selects reinforced solar glass materials that balance weight with the strength to make sure our panels are reliable while being easy to handle.

Our panels are tested against 35 mm ice balls travelling at 100 km/h to make sure they can withstand hail impact.

The anti-reflective coating on the glass also maximises the amount of light that reaches solar cells for best performance.

Dust Build-Up Near Panel Edges Can Shade Solar Cells

When solar panels are placed on rooftops at a gradual slope, the module frames may collect rainwater into a stagnant pool.

Dust residue is left behind when the water evaporates to create unwanted shade and reduce energy production from solar cells.

solar panels dust build up
Dust tends to build up at the edge of the module frame after rain.

WINAICO’s unique frames are specially designed with sloping profiles and drainage channels to help water run off the surface, cleaning away dust and dirt in the process.

Cracked Solar Cells Are Signs of Poor Production Quality

Not all solar module production lines are created equal.

A poor production line may accidentally laminate cracked solar cells into solar panels and introduce mismatch to cells that impact power production.

cracked solar cells
Chipped solar cells reduce energy production of a solar module.

WINAICO’s production line automates the solar cell stringer to screen out imperfect cells before soldering ribbons to minimise conduction resistance.

Poor Connection in Solar Cell Strings Can Reduce Energy Production by 1/3

After solar cells are connected into strings, they are soldered into interconnection wires to complete the array inside a panel.

We have seen solar panels with poorly soldered interconnections that cause 1/3 of the solar cells to become open-circuited, reducing the energy production of the panel by 1/3 or more.

poor solar panel soldering interconnection
The open-circuit within a solar panel can be detected using an IR camera.

The open-circuit can be detected using an IR camera to see a significant temperature difference between solar cell strings.

This pv module defect can be prevented by more mature manufacturing techniques and careful EL inspection before shipping.

A Defective Junction Box Can Leave a Solar Panel in Open Circuit

A junction box at the back of a solar panel is the key interface to conduct electricity to the outside.

If water or dust seeps into the junction box enclosure, the bypass diodes inside can become short-circuited and burn out.

A burnt bypass diode or connector can leave the panel in open circuit and stop transferring energy outward altogether.

broken solar junction box
A broken junction box with burnt bypass diodes can stop conducting electric current out of the solar panel.

WINAICO carefully selects IP67 rated junction boxes that stop dust and water from trickling in to damage the circuits.

Snail Trails Can Be Signs of Microcracks

When the underlying solar cells are broken, cells can continue to generate electric current along the cracks, causing localised heat that breakdown the cell surface and EVA.

If water vapour is also present, discoloured snail trails are formed along the microcracks to not only reduce energy production but also compromise appearance.

common solar panel defects snail trail
Snail trails can be signs of microcracks in the underlying solar cells.

The best way to reduce snail trails in solar panels is to choose reliable encapsulation materials to prevent water vapour from entering the laminate, and handle panels carefully to prevent microcracks from forming.

PID Degradation Damage Solar Cells and Reduce Energy Yield

Solar panels are usually connected in long series to create high system voltage, sometimes as high as 1000 V, to drive solar inverters.

The high voltage difference between the grounded frames and solar cells may be too much for poor quality solar cells to handle and may begin to deteriorate.

WINAICO prevents PID degradation by putting solar panels through enhanced PID tests in our reliability labs to make sure our components do not breakdown under high system voltages.

Uneven Cell Colours Make Ugly Installations

Full black solar modules with black backsheets are especially important in residential applications that value aesthetics over performance.

It is especially important to keep the solar cell colours uniform on full black panels to prevent blotchy colours on black roofs.

uneven solar cell colours
Uneven solar cell colours can result in disappointing full black installations.

WINAICO meticulously sort solar cells into categories by colour before production to make sure every full black solar panel from WINAICO is consistent in colour for the best appearances.

Cracked Backsheet Provides Poor Water Insulation

Solar panel components are exposed to intense UV radiation and temperature variations every day.

Cracked backsheets are signs of poor component selection and can cause water vapour to enter module laminate to damage solar cells.

cracked solar panel backsheet
A cracked backsheet cannot insulate solar cells from water damage.

WINAICO put solar panels through Damp Heat and Thermal Cycling reliability tests to qualify the most reliable EVA and backsheet materials for solar applications.

Our solar module design philosophy is all about high performance and reliability.

When you choose WINAICO solar panels, your investments are protected from these common solar panel defects.

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