Understanding your microcrack loss
What microcracks are and how they cause output loss
Microcracks are tiny fractures within a solar cell, often invisible to the naked eye, that disrupt the electrical path through the cell and create localized resistance. Depending on severity, they can cause anywhere from a barely measurable loss to a meaningful reduction in that panel's output. Unlike a manufacturing spec issue, this is physical damage to the cell structure itself. A DOE assessment of 75 federal PV systems found availability and performance ratio can decline together as equipment ages, consistent with the kind of gradual loss microcracks can cause.
Why microcracks tend to worsen rather than stay stable
They often worsen gradually. Repeated thermal expansion and contraction from daily and seasonal temperature swings can slowly widen an existing microcrack, which is why a crack detected years ago may be causing more loss today than when it first appeared. This progressive nature is what distinguishes microcracks from a one-time manufacturing defect. NLR's PV Fleet data, drawn from thousands of real installed systems, has documented this same pattern of gradual, thermally-driven degradation accelerating over a system's lifetime rather than staying flat.
Common causes worth knowing about
Common causes include rough handling during shipping or installation, hail impacts, foot traffic on panels during maintenance, and normal thermal cycling stress that accumulates over years of temperature swings between day and night. Understanding the likely cause can help prevent additional cracks from forming in the future. Check the year 10 output estimator to see how this loss fits alongside normal expected degradation. If a specific hail event is the likely cause, the hail damage roof and panel repair estimator covers the combined repair picture rather than just the output side.
How microcracks are actually detected
Electroluminescence, or EL, imaging is the standard professional method, using a specialized camera to reveal crack patterns that are completely invisible under normal light. Some installers offer this as part of a system health inspection, particularly useful after a hail event or if output seems lower than expected.
What to do with this number next
If your loss estimate seems significant, compare it against the hotspots estimator, since severe microcracks can sometimes lead to hotspot formation over time, and check the string mismatch loss calculator to see how affected panels interact with the rest of their string.