Silver's industrial demand profile has changed substantially over the last decade, and solar manufacturing is the largest reason. The metal's role in a panel explains why.
Silver carries the current off the cell
A photovoltaic cell generates electricity across its whole surface, and that current has to be collected and conducted away without shading the cell from the light it needs.
Fine lines of silver bearing paste are screen printed onto the cell to do this, because silver has the highest electrical conductivity of any metal and can therefore carry the current in the narrowest possible lines.
The paste is then fired at high temperature so the lines bond electrically to the cell beneath, forming the fine grid visible on the face of a finished panel.
Cell design changes the quantity needed
Manufacturers have worked continuously to narrow the printed lines and reduce paste consumption, since silver is a significant part of a cell's material cost.
Newer cell architectures that raise efficiency have sometimes required more silver per cell, partly offsetting those reductions.
Consumption per panel is therefore the outcome of two opposing engineering pressures rather than a figure that only falls.
Installed capacity has grown faster than efficiency savings
Global solar installation has expanded strongly over the period, and the number of panels produced has grown accordingly.
Because the reduction in silver per cell has been gradual while installation growth has been rapid, total silver demand from the sector has risen substantially.
This turned a minor industrial use into one of the largest single sources of demand for the metal.
Substitution research runs continuously
Copper is cheaper and nearly as conductive, and considerable effort has gone into replacing silver with copper based metallisation.
The difficulty is that copper oxidises and can diffuse into the cell, degrading it, so barrier layers and different deposition methods are required.
Commercial adoption has been slower than expected, because a panel must maintain performance for decades and manufacturers are cautious about unproven changes.
Consumed silver is hard to recover
Silver in a panel is spread as a thin film across a large laminated surface bonded to glass and polymer.
Recovering it requires dismantling the panel and processing the cell material, which is expensive relative to the quantity obtained.
Most of the metal therefore leaves the market for the life of the installation, which distinguishes this demand from jewellery or investment holdings that can return to it.