Solar PV

Solar panels yellowing or delaminating

Warning Do not attempt any electrical or gas work yourself. Always use a qualified, MCS-certified, or Gas Safe registered professional for repairs.

What you’re seeing (symptoms)

You notice that the solar panels on your roof are starting to look yellow or brown in certain areas. You may also see “bubbles” or a milky-white appearance under the glass, or a “peeling” effect at the edges.

What’s normal vs not normal

Normal:

A slight “blue” or “black” tint depending on the panel type (Polycrystalline vs Monocrystalline).
A thin layer of dust or pollen that washes away with rain.

Not normal:

A distinct “yellowing” of the internal plastic layer (EVA).
“Snail trails”—thin, dark, wavy lines on the surface of the solar cells.
Visible “bubbles” or “pockets” of air between the glass and the cells (delamination).
Corrosion or rust visible on the internal silver busbars.

Likely causes (ranked)

Poor quality EVA: The plastic “glue” (EVA) used to sandwich the cells together is of low quality and is reacting to UV light, causing it to turn yellow and brittle.
Moisture ingress: The seal at the edge of the panel or around the junction box has failed, allowing water to enter the panel and cause delamination.
High-temperature stress: Panels in very hot climates (or those with poor ventilation) are more prone to the chemical breakdown of the EVA layer.
Manufacturing defect: A batch issue at the factory where the panels weren’t “vacuum-sealed” correctly during lamination.
Micro-cracks: Physical damage to the cells (e.g. from people walking on the panels during installation) can lead to localized “hot spots” and browning.

Quick checks you can do safely

Visual check: Use binoculars or a camera with a good zoom to look at the panels from the ground. Look for “bubbles” or “browning” specifically around the edges of the cells.
Monitor generation: Delaminated panels usually have much lower production. Check your solar app for a drop in generation compared to previous years.
Check the back: If you have access to the loft and can see the underside of the panels (rare), look for “burn marks” or brown spots on the back-sheet.

When to call an installer

Immediately if you see “burn marks” or smoke, as this is a fire risk.
If you see significant bubbling (delamination) covering more than 5% of a panel.
If you want to perform a “thermographic” (thermal) scan to find hot-spots caused by cell failure.

Questions to ask your installer

“Are the panels covered under the manufacturer’s 10-year or 25-year product warranty?”
“Is the generation drop enough to trigger a performance warranty claim?”
“Do the panels need to be replaced, or can the delamination be repaired (rare)?”

FAQs

What is EVA? It’s a plastic film (Ethylene Vinyl Acetate) used to “laminate” the solar cells between the glass and the back-sheet. It’s designed to be transparent and protect the cells. Is yellowing dangerous? Usually, no. It just reduces the amount of light reaching the cells, which lowers your generation. However, if it leads to “hot spots,” it can be a fire risk. What are ‘Snail Trails’? They are tiny cracks in the solar cells that allow moisture to enter. The moisture reacts with the silver in the cells to create a dark “trail” that looks like a snail has crawled over the panel. Will my insurance cover it? Unlikely. This is usually considered a “manufacturing defect” or “wear and tear,” which are excluded from home insurance. You should contact the panel manufacturer or your installer. How long should panels last? High-quality panels are designed to last 25-30 years with less than 20% loss in generation over that time. Delamination in the first 10 years is a sign of a faulty product.\n

Written by NetZeroNow | Last updated on 2026-03-02

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