Silver in Solar Cells: The Cell Line's Most Watched Consumable

Every architecture has a different silver appetite

Metallisation is the step that turns a passivated wafer into a cell that can deliver current, and on most lines it is done by screen-printing silver-based pastes and firing or curing them. How much silver that takes depends on the architecture. The ITRPV 17th edition, reported by TaiyangNews, gives 2025 averages per M10 cell of approximately 70 mg for PERC, 88 mg for TOPCon, 100 mg for HJT and 104 mg for IBC/TBC back-contact cells — around 10 mg per watt for TOPCon.

The ordering matters for Indian projects. The industry's move from PERC to TOPCon, and on the roadmap toward back-contact, has been a move toward architectures that use more silver per cell, not less. Heterojunction is a special case: its low-temperature process uses low-temperature pastes, and it is also where copper substitution is moving fastest. A line's metallisation bill therefore follows its architecture choice, and should be modelled with it rather than carried over from a PERC reference.

• Model silver per cell for the architecture actually being built
• Do not carry PERC-era silver assumptions into a TOPCon or BC line
• Treat HJT low-temperature pastes as a separate supply category
• Track silver per watt as a line KPI, not only paste price

Why PV silver demand is falling while production rises

The World Silver Survey 2026, reported by pv magazine in April 2026, recorded PV silver demand of 186.6 million ounces in 2025, down 6%, and forecast a further 19% fall to about 151 million ounces in 2026. The cause is not less solar. It is thrifting and substitution: lower silver loadings per cell that more than offset continued growth in cell output. On the same survey's figures, PV still accounted for a large share, roughly 28%, of global industrial silver use in 2025.

The ITRPV roadmap points in the same direction over the longer term. It expects silver per M10 cell to fall to around 57 mg for TOPCon, 40 mg for HJT and 60 mg for back-contact by 2036, through finer metallisation patterns, lower paste laydown and multi-busbar designs. For a cell maker, that means the paste specification is a moving target: the paste qualified at commissioning will probably not be the paste the line runs five years later.

• Plan for repeated paste requalification over the life of the line
• Ask paste suppliers for their laydown-reduction roadmap
• Treat finer printing and multi-busbar capability as line requirements
• Re-check demand forecasts with each new survey edition

Copper and plating are on the roadmap, not yet the default

The ITRPV expects copper-based metallisation to gain importance in HJT, back-contact and tandem cells. For HJT specifically, it forecasts silver-based metallisation falling from around 75% of production in 2025 to about 10% in 2036, with silver-coated copper and pure-copper technologies taking most of the remainder.

Plating is the more radical route. Fraunhofer ISE reported in April 2026 a process combining ultrashort-pulse UV laser structuring with electrochemical deposition of nickel, copper and a thin silver layer, cutting silver in TOPCon cells from the standard 10–12 mg per watt-peak to 1.1 mg/Wp, while reaching 24% efficiency on M10 cells and a fill factor of 82.1 ± 0.3% across a 186-cell batch. The institute's own framing is that nickel/copper electroplating could be firmly established in the market within two to three years — a direction of travel, not present-day qualified capacity.

For a line being specified now, the practical response is to keep the metallisation bay reviewable: printer generation, laser capability, curing or firing flexibility and floor space, so that a later move to lower-silver or copper-based contacts is a retrofit rather than a rebuild.

• Leave space and utilities in the metallisation bay for a later retrofit
• Ask which copper or plating routes the chosen tools can accept
• Treat plating results as roadmap until qualified at production scale
• Include reliability testing in any copper-contact qualification

India's supply position

Silver paste sits on the list of cell-line inputs India still imports. A pv magazine India commentary in August 2026 listed silicon wafers, polysilicon, silver paste, specialty chemicals and high-purity consumables as essential raw materials that remain heavily import dependent, alongside much of the critical equipment. Domestic cell capacity has grown quickly under ALMM List-II, which came into force for solar cells on 1 June 2026, and every gigawatt of new cells adds to paste demand.

The upstream metal is also subject to trade policy. Business and trade press reported that on 16 May 2026 the Directorate General of Foreign Trade moved silver bars containing 99.9% or more silver by weight (ITC HS 71069221) and other silver bars (71069229) from the Free to the Restricted import category, so imports now require authorisation. How that affects any given paste supply chain depends on where the paste is made and in what form the silver enters India, which is exactly what a cell project should establish with its suppliers. Current rules should be confirmed directly with DGFT.

• Map where each paste is made and how its silver enters India
• Confirm the current DGFT import position before relying on a supply route
• Qualify more than one paste source per critical print step
• Hold safety stock in line with lead time and requalification time

Treating paste as a managed consumable

Paste is formulated against a specific cell architecture, surface and firing or curing profile, so it behaves less like a commodity and more like a qualified material. Changing supplier, formulation or even laydown usually means a qualification run with efficiency, contact resistance and reliability data, not a purchase order.

That makes metallisation consumables a natural place for disciplined supply management: approved-source lists per print step, shelf-life and storage control, incoming inspection, laydown monitoring per cell, and a documented requalification route for every change. None of that requires a view on silver prices. It requires treating the most closely watched consumable on the line with the same rigour as the wafer that goes under it.

• Keep an approved-source list for every paste and print step
• Control paste storage, shelf life and handling on the floor
• Monitor laydown per cell as a routine quality metric
• Document a requalification route before any paste change