The Boring Inputs Are Tight: Aluminium at a 36-Year Low, Steel at $1,200

Written 11 September 2026, on LME stock data for the week to 4 September, Fastmarkets reporting on US mill outages, and coverage of the Canada-US tariff escalation.

Two of the dullest inputs in a battery project are both tight at once. Aluminium stocks on the London Metal Exchange fell to their lowest since 1990 — total stock around 244,500 tonnes in the week to 4 September, roughly half where the year started. US hot-rolled coil is near $1,200 a short ton against about $800 a year ago.

Neither is a battery material. Both are what a battery arrives inside.

• •LME stocks down around half since January, the lowest level since 1990
• •Canada imposing counter-tariffs of up to 50 per cent from 8 September, explicitly covering aluminium, against US duties already in place
• •Canada supplied around 60 per cent of US unwrought aluminium imports in the first half of 2026, so the dispute is not a marginal trade flow
• •Middle East supply disrupted by the Iran conflict, with Gulf output sharply down year on year

Aluminium is in a pack enclosure, the busbars, a solar module frame and its mounting, and overhead conductors. It is also energy-intensive to smelt, which ties it to power prices — so an energy shock reaches it twice, once through demand and once through the smelter bill.

The steel story is more specific and more predictable, which makes it easier to plan around. More than a million tons of US hot-rolled coil production is coming out of the market through planned mill outages between September and December 2026, with September the heaviest month. Spot availability is already tight and lead times are running 8 to 12 weeks.

Underneath that, the Section 232 tariff remains at 50 per cent. Talk of cutting Canada’s rate has not been signed, and an unsigned proclamation is not a price cut.

In storage, in the balance of plant — the containers, the plinths and structural steel, the switchgear enclosures, the fencing the safety rules now require at 1.8 metres. Those are a larger share of a project than people new to storage expect, and they are bought late, which is exactly when a squeeze bites.

• •Containerised BESS enclosures, which are steel and are imported
• •Structural steel and mounting for solar, where a frame is aluminium and a table is steel
• •Transformer and switchgear housings, already scarce for other reasons
• •Pack enclosures and busbars in mobility products

Our note on what actually happens between order and energisation makes the same point about lead times: the long poles are rarely the cells.

Order the structural items earlier than feels necessary, and fix prices where a supplier will. The scheduled nature of the steel outages is a gift — it is a known supply reduction with published dates, which is the rare case where a procurement team can act before the market does rather than after.