Deep processing: what happens after the module has been dismantled
Dismantling produces fractions. Deep processing turns those fractions into products — or into a cost. This section covers the four routes that matter
01
How a tunnel kiln works
A tunnel kiln is a long heated chamber through which material travels on carriages. Rather than heating a batch and waiting, the material passes through zones that hold different temperatures, so each stage of the process happens in its own section of the kiln and the throughput is continuous.
For module delamination the principle is the same as for a batch thermal process: the encapsulant is driven off thermally, and what remains is glass with the laminate chemistry removed. The difference is scale and continuity — and the fact that a continuous kiln demands a consistent feed. A batch oven tolerates variation; a tunnel kiln turns variation into a quality problem spread across the whole run.
02
The kiln in section
03
What each zone is for
| Zone | Purpose | What it decides |
|---|---|---|
| Entry and preheat | Bring the laminate up to temperature without thermal shock | Glass breakage at the entry end — the most common quality loss |
| Delamination | Drive off the encapsulant and backsheet | Whether the glass comes out clean or still carrying residue |
| Hold | Complete the removal across the full area of the module | Consistency between the leading and trailing edges of each pane |
| Controlled cooling | Cool the glass without introducing stress | Whether the panes survive to be graded, or crack after the kiln |
| Discharge | Transfer the processed material to screening or grading | Dust and fume capture at the hottest transfer point |
04
The part nobody puts on a datasheet: the fixture
How the module is supported on the carriage is one of the most consequential decisions in a tunnel kiln project, and it is frequently settled last. A pane supported only at its edges will sag and crack as it softens; a pane resting flat on a solid tray will not see even airflow; a fixture that holds the laminate too rigidly will not accommodate the differential expansion between the glass and the material around it.
The practical requirements are that the fixture supports the pane across its area, resists the operating temperature without deforming, allows the vapour to leave freely, and can be loaded and unloaded at a rate that matches the kiln. In practice, plants that get the kiln right and the fixture wrong get inconsistent glass and blame the temperature profile.
05
When a tunnel kiln is the right answer
- You need continuous delamination at scale. A tunnel kiln buys throughput that batch equipment cannot match.
- Your feed is consistent. A steady stream of frameless laminates of similar size and build is the ideal input.
- Your glass buyer requires low residue. The route exists to bring cullet up to a specification mechanical separation cannot reach.
- You can carry the abatement and the permit. Continuous thermal operation means continuous extraction and treatment of the off-gas.
- You have the labour model for carriage handling. Loading and unloading fixtures is a real, recurring operation, not a one-off.
06
Tunnel kiln or pyrolysis reactor
| Tunnel kiln | Pyrolysis reactor | |
|---|---|---|
| Mode | Continuous | Batch or continuous |
| Feed | Flat frameless laminates | Dismantled material, including mixed and smaller fractions |
| Main output | Glass with the encapsulant removed | Gas, oil and a solid residue |
| Recovers the polymer as | Off-gas, extracted and treated | Oil and gas, recovered as products |
| Feed consistency required | High — variation spreads across the run | Moderate — batch operation tolerates more variation |
| Best fit | High-volume delamination for glass recovery | Polymer destruction or recovery where oil has a use |
Continuous or batch?
It depends on your feed consistency and your labour model more than on tonnage. Tell us both and we will tell you which configuration the project supports.
FAQ
Questions
What is a tunnel kiln used for in solar panel recycling?
Continuous thermal delamination. Frameless laminates travel through a controlled temperature profile that drives off the encapsulant and backsheet, leaving glass that can be graded and sold rather than glass carrying polymer residue.
Does the frame have to be removed before the kiln?
Yes. The frame is removed first, on the deframing machine, so the aluminium is recovered as a clean metal stream. Sending framed modules to a tunnel kiln gives away that value and contaminates the residue.
What limits the quality of the glass that comes out?
Two things: the temperature profile, and how the pane is supported on the carriage. Fixture design is the more frequently underestimated of the two — a pane supported only at its edges will sag and crack as it softens.
What happens to the vapour driven off in the kiln?
It is extracted and treated. Continuous thermal operation means a continuous off-gas stream, so the extraction and abatement train is part of the project scope and part of the permit — not an optional extra.
Is a tunnel kiln better than a pyrolysis reactor?
They solve different problems. A tunnel kiln is optimised for high-volume delamination of consistent flat laminates. A pyrolysis reactor handles more varied dismantled material and recovers the polymer as oil and gas. The choice follows from your feed and from whether the oil has a use.
Send us the module mix and the through-put
Tell us what arrives at your gate and what has to leave. The engineering team replies with the station configuration, the scope boundary and the information still missing before drawings start.
- Modules — framed single-glass, double-glass, frameless, thin film, mixed
- Condition — intact, or a meaningful share damaged or bent
- Through-put — modules per hour or t/h, and your shift pattern
- Output — which fractions you sell or store, and to what specification
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