A panel can look perfect and still be damaged. Micro-cracks in the silicon cells and hot spots on the surface are two common hidden problems. They often start small and get worse over time.
- Never stand, kneel or place tools on panels.
- Carry panels on their edges, two people for large panels.
- Clean regularly so droppings and leaves don’t create hot spots.
- Check for brown marks, snail trails or discoloured cells.
What are micro-cracks?
Solar cells are thin slices of silicon, and silicon is brittle. Tiny cracks can form if a panel is bent, dropped, stepped on, or hit by hail. You usually can’t see them with your eyes. Over years of heating and cooling, the cracks can grow and cut off parts of the cell, reducing output.
Common causes
- Rough handling during transport, stacking panels flat with weight on top
- Installers walking on panels
- Over-tightened clamps
- Strong wind flexing panels on a weak structure
- Hail or falling objects
What are hot spots?
When part of a panel is shaded or a cell is damaged, that cell can stop producing and start resisting current from its neighbours. It heats up, sometimes a lot. Over time this can discolour the cell, damage the backsheet, and in severe cases even burn through.
Common hot spot triggers
- Bird droppings left for weeks
- Leaves or plastic bags stuck on a panel
- Permanent partial shade from a wire, pole or tank edge
- A cracked or defective cell
Signs to look for
- Brown or burnt-looking spots on cells
- “Snail trails”, thin dark lines across cells, often a sign of cracks
- Bubbles or yellowing in the back sheet
- One string producing noticeably less than an identical one
How professionals check
Thermal cameras show hot spots clearly as bright patches. Electroluminescence (EL) imaging reveals micro-cracks, usually done at the factory or by specialists. For homes, a thermal check of a suspect string is often enough.
Prevention
Handle panels carefully, never walk on them, use proper clamps tightened to spec, keep panels clean, and design the layout to avoid permanent shade. See our shading guide and cleaning guide.
Warranty
Manufacturing defects are usually covered, but physical damage from handling or walking is not. Take photos of panels on delivery and after installation, it helps if you ever need to make a claim.
See brown spots on your panels?
Send a clear photo. We’ll tell you whether it’s dirt, a hot spot or something to claim.