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Microcracks in solar panels: the invisible yield killer

A microcrack is a hairline fracture in a silicon cell, often thinner than a hair. You can't see it, your installation seems to work — and yet it costs you yield year after year. How do you recognise something invisible by definition?

Why does this matter?

Microcracks are rarely an immediate problem: a fresh crack often causes almost no loss. The sting is in time. Under thermal expansion, vibration and moisture the cracks grow until they electrically isolate part of the cell. That section no longer contributes, the active area shrinks and the yield drops — slowly and creepingly. Anyone who waits for the inverter to raise the alarm almost always acts too late.

What exactly is a microcrack?

Silicon is hard but brittle. An impact — hail, a rough transport ride, a footstep during mounting — can leave hairline cracks in the cell beneath the glass. As long as the crack does not interrupt the current path, you notice nothing. Once it does, part of the cell becomes isolated. That is different from potential-induced degradation (PID) or a faulty bypass diode; each leaves its own signature, and it is precisely that distinction that makes a good inspection valuable.

How does this work in practice?

You cannot photograph a microcrack, but you can measure its consequence: heat. An isolated cell section no longer carries current under load and heats up. With a radiometric thermal camera that shows up as a hotspot — and the pattern tells the story:

• One warm cell corner or strip: typically a microcrack isolating part of one cell.
• A warm checkerboard or patchwork pattern across several cells: extensive cell damage, often after hail.
• An entire warm substring: usually an activated bypass diode — a different defect we deliberately keep apart.

We read these patterns in flight with a Matrice 30T. The radiometric data gives the temperature per pixel, so we can tell a real hotspot from a reflection and gauge severity instead of guessing.

Common mistakes

• Waiting until the yield visibly drops. By then several cells are usually already affected.
• Only checking visually. Microcracks are invisible; only their thermal consequence is measurable.
• Measuring in too little sun. Without enough load, faulty cell sections don't heat up enough.
• Using an ordinary thermal photo. Without radiometry you cannot quantify or compare patterns.
• Never repeating. One measurement is a snapshot; only a second shows whether the damage is growing.

Why with a drone?

With a drone you scan large numbers of panels quickly under equal lighting, which makes the hotspot patterns comparable. Every finding gets a GPS position, and because the flight is repeatable, you can redo the exact same measurement a year later to see whether a microcrack is worsening. That is the difference between a suspicion and a substantiated decision to replace or claim.

Why Droneview?

Droneview is EASA-certified and specialised in radiometric PV thermography with the Matrice 30T. We have scanned hundreds of installations and learned to read the patterns that tell a microcrack apart from a diode effect or soiling — with a clear, measurable report as the result.

Frequently asked questions