Teaser: A module that leaves the roof intact is not necessarily the same module that arrives at the test bench. A large share of damage that later gets labeled "ageing" is actually transport damage: microcracks from vibration, glass breakage from bad stacking, frame pressure on the front glass. Transport is the most underrated value-destroyer in the PV lifecycle.
A detail the entire industry knows — but rarely enforces consistently
Factory-fresh PV modules always leave the plant standing on pallets. The big manufacturers package this way because the physics is uncontroversial: in a horizontal stack, the bottom module carries the full weight of everything above it, plus dynamic spikes from transport vibration. The front glass is loaded from inside by the frame and from outside by the stack — exactly where it is not meant to take load. With today's module formats (up to 2.50 m × 1.40 m, 25–35 kg), a few hundred kilometres of truck transport are enough to seed invisible microcracks in the lower modules.
Field studies and quality reports confirm this. TÜV Rheinland and ISFH put the share of PV modules that already carry transport- or vibration-induced damage before installation at around 6 %. On the packaging side, the industry routinely cites 2 to 5 % as the typical shipping breakage baseline, with optimised packaging bringing that number down to roughly 0.5 % according to manufacturer data.
The standards reflect how seriously this is taken. IEC 62759-1 defines a standardised transport simulation based on randomised vibration profiles. IEC TS 62782 covers the cyclic mechanical load test. Both standards exist because transport is not an edge case — it is a predictable load scenario.
What actually happens inside a horizontally transported module
Three mechanisms act in parallel, and all three scale with travel time:
Cell cracks from vibration. Solar cells are brittle silicon wafers, today 150–170 µm thin. The 5–200 Hz frequency band — the typical trucking and road vibration range — induces bending modes that propagate along the finger metallisation. The cracks often run perpendicular to the busbars and remain electrically silent until thermal cycling widens them later. They show up in EL imaging as "dendritic cracks" — one of the most common findings in field thermography and post-mortem analysis.
Accumulated frame pressure in the stack. In horizontal stacking, mechanical load grows geometrically from top to bottom. The frame of one module presses into the glass of the module below, especially when foam spacers are missing or modules shift in cornering. The glass does not fail catastrophically; it develops hairline cracks that open up on the next thermal or mechanical event.
Glass breakage from shifting. The visible version of the problem. A module whose frame edge ends up resting on a neighbour's front glass is a total loss. These are the modules flagged at arrival — and statistically the most visible fraction of transport damage, but far from the biggest.
Why this is not only an installation issue
Transport damage gets filed away as a new-install problem. That is only half true, and only for factory-fresh modules. Every later intervention in the lifecycle creates the same problem, often in amplified form, because used modules are routinely handled without original packaging:
O&M and module replacement. A module uninstalled intact and then trucked horizontally on a Euro-pallet to the test lab often arrives cracked. The module was healthy in the field, and ready for a warranty claim by the time it hits the bench — a pattern we see repeatedly in 2nd Cycle's damage analysis work.
Reuse and second life. When a module clears the reuse threshold — electrically and optically inside the datasheet envelope — the transport to its second installation decides whether it stays there. Microcracks that are still tolerable in the EL image can cross the threshold after a second road leg. Second life is only as robust as the logistics behind it.
Recycling. The connection is rarely named but economically decisive. High-quality PV recycling with sorted glass recovery depends on intact modules. Once the glass breaks during transport or disassembly, glass cullet mixes with backsheet, EVA and metallisation residues. The output then often only qualifies for downcycling — foam glass, abrasives, road base. The price gap between sorted flat glass and mixed cullet is not a detail; it defines the whole recycling economy.
At each of the three stages, the same rule applies: a module that has cracked cannot be un-cracked. The damage is permanent, and it is carried through every station between original site and final recycler, with value loss at each step.
Why we built the SolarBox
We did not find this problem in theory. We found it in practice, over years, at every interface: quality-checking newly installed plants, assessing storm and hail damage, receiving returned modules from repowering projects, feeding daily recycling input. The pattern was always the same. Modules that arrived horizontally stacked were, on average, worse than modules that travelled vertically. And diagnostics can record transport damage, but not undo it.
The SolarBox is our direct response to that reality. A standardised vertical transport system that accepts modules up to roughly 2.50 m × 1.40 m — independent of manufacturer, frame height or production year. Unfold, load, stack: each module carries only its own weight, frame edges never touch neighbouring glass, and the box itself absorbs the dynamic load from vibration and stacking. It is built robot-compatible so that loading and unloading can be automated downstream — because handling time is also risk time.
The benefit is unglamorous in description and drastic in effect: fewer microcracks, less glass breakage, less value loss on every route a module takes between rooftop, test bench, intermediate storage and final processing.
Bottom line
Transport is not a sideshow in the PV lifecycle. It is one of the most systematic sources of value destruction in the chain. A module that is intact at the moment of removal and damaged on arrival changes the whole economic case — from warranty claim to reuse to recycling. Horizontal stacking is an implicit acceptance of that loss. Vertical transport is a deliberate defense of value that has already been produced and does not need to be produced again.
Learn more about the SolarBox: https://www.2ndcycle.at/solarbox-landingpage
Sources:
- IEC 62759-1:2022, Photovoltaic (PV) modules — Transportation testing (randomised vibration simulation)
- IEC TS 62782:2016, Cyclic (dynamic) mechanical load testing of PV modules
- Papageorgiou et al. (2022), Defect object detection algorithm for electroluminescence image data (6 % transport/vibration damage before installation, citing TÜV Rheinland / ISFH)
- WINAICO, 4 Keys to the Most Reliable Solar Panel Packaging (2–5 % industry average, < 0.5 % with optimised packaging))
- Solar Power World (2024), The delicate matter of protecting solar panels during shipping, handling and extended storage
- IEA-PVPS T13 Failure Reports, Review of Failures of Photovoltaic Modules (transport and handling defects as distinct cause cluster)