Single-glass and double-glass modules behave differently on a dismantling line

A conventional single-glass module is a front pane of tempered glass, two layers of encapsulant with the cell string between them, and a polymer backsheet on the rear. A double-glass module replaces that backsheet with a second pane of glass. Everything else — frame, junction box, cell technology — can be the same.

That one substitution has three consequences for recycling. The module is heavier and its mass is more evenly split between two panes. The edge of the laminate is a glass edge on both faces rather than glass on one and polymer on the other. And the frame, if present, is bonded and sealed against two glass surfaces instead of one.

Frame removal works the same way in principle on both designs, but the tolerances tighten on double-glass. The laminate edge is glass on both faces, so an over-pressed clamp or a cutting head that bears on the edge will chip it. Chipped glass then travels into the cullet stream as fragments with a different size distribution, which some glass buyers penalise.

In practice this is managed with three adjustments: lower and more evenly distributed clamping pressure, support that carries the module across its whole area rather than at two rails, and tooling sized to the actual frame profile rather than to a nominal one. None of these are exotic, but they are not the default setting of a machine specified for single-glass poly either.

A frameless or glass-glass module has no aluminium frame to recover, so the deframing machine is not the right first station — the process starts at the junction box. That is a structural change to the line layout, not a parameter change, and it is the single most common surprise in a line enquiry where the buyer has not yet sorted their feedstock.

The practical answer for a plant handling both framed and frameless modules is usually to run them as separate batches rather than to design one line that does both at once. Batch separation costs a changeover and saves a machine.

This compares the three designs as feedstock. Module vintages, frame profiles and cell technologies vary within each column, so a real project is planned from a sample of the actual consignment.

Most plants receive a mix, and the proportion of double-glass rises every year as the newer module generations reach end of life. A line specified today for a feedstock that is 90% single-glass will be wrong within a few years, so the sensible question is not what you are receiving now but what you will be receiving in five years — and whether the machine can be adjusted to meet it.

Machines that carry their clamping pressure and tooling as adjustable parameters, rather than as fixed mechanical settings, age better for exactly this reason. If a specification conversation does not cover how clamping and tooling are changed, that is a gap worth raising before the order rather than after.