Thermal imaging for microcracks — when it matters.
Short answer: Microcracks in solar cells are invisible to the eye but glow on a thermal camera — they run 2–10°C hotter than surrounding cells during operation because their resistance is higher. Most modern panels have a few microcracks at install (from shipping or installation handling); they don't matter until they cascade. Thermal imaging during the annual inspection finds them while warranty claims are still possible. Standalone scan $189, included in the annual inspection.
What causes microcracks
- Manufacturing variations — silicon wafers leave the factory with some microscopic stress; minor cracks may be present from day 1
- Shipping — vibration during truck transport can crack cells; especially common in older modules with less-robust EVA encapsulant
- Installation — installer foot pressure on panels (illegal but common), drops during handling, over-torqued fasteners flexing the frame
- Thermal cycling — daily heat-up/cool-down over years stresses the silicon. Older panels (10+ years) accumulate more
- Hail or impact — major events can crack cells without breaking glass
- Wind loading — rare but possible on improperly-mounted arrays
Why thermal imaging works
An active solar cell with a microcrack has slightly higher electrical resistance. Higher resistance + same current = more heat dissipated. The damaged cell runs 2–10°C hotter than its neighbors. Visually invisible; thermally obvious.
Network specialists use FLIR or equivalent infrared cameras during the annual inspection. They walk the array (or use a telescoping pole) and image every panel from both sides where accessible. The thermal image reveals hot-spots, which the specialist marks for documentation.
What microcrack findings mean
- 1–2 minor hot-spots per panel — normal. No action needed.
- 3+ hot-spots in a single panel — significant. May warrant warranty claim or panel replacement.
- Large or progressive hot-spot — actively damaging the panel. Replacement recommended.
- Hot-spots forming a pattern (line, cluster) — likely impact damage (hail, debris). Document for insurance claim.
The warranty timeline
Manufacturer warranties typically have two clauses:
- Workmanship warranty — typically 10–12 years, covers manufacturing defects. Microcracks discovered in this window often warrant free replacement.
- Power output warranty — typically 25 years, covers panels degrading more than X% per year. Microcracks contributing to output decline are covered partially.
Best time to scan: year 5–10. Late enough that minor cracks have surfaced; early enough that workmanship warranty still applies for free replacement.
If your panels are 8–11 years old: the annual inspection (which includes thermal imaging) is a high-ROI scope. Finding microcracks in year 9 gets you free panel replacement under workmanship warranty. Finding the same cracks in year 12 means partial credit against the output warranty — typically half the value.