The photovoltaic industry is actively seeking to reduce its dependence on silver, an essential but expensive material in the manufacture of photovoltaic panels. The increase in production volumes is making critical the scarcity of resources and the volatility of the cost of this material. In 2022, the manufacture of photovoltaic panels accounted for almost 12% of global silver consumption, a proportion that is set to rise steadily as the introduction of renewable energies accelerates.
Manufacturers are therefore implementing ways of reducing the amount of silver used per cell, and then in assembling them into modules. Some pioneering companies have even achieved levels below 10 mg/W, thanks to innovations in screen-printing techniques[1]. The ultimate target is to reduce consumption even further, and eveDemonstrator Mini-module using cells metallized with copper-silver pastes and interconnected with copper ribbons, produced by the CEA laboratories at INESn to replace silver entirely with alternative materials such as copper.
The goal is therefore to continue improving photovoltaic performance while reducing the economic and environmental impact of silver extraction, without compromising their life span.
In a study designed to reduce the amount of silver used in BusBar ECA interconnection technology, CEA laboratories tested new low-silver Electrically Conductive Adhesive (ECA) materials, both in combination with standard silver-coated tapes and with tapes coated with tin or pure copper.
Among the various combinations explored, the one using cells metallised with copper-silver pastes and interconnected with copper ribbons enabled us to achieve a total silver consumption in the photovoltaic panel of less than 14 mg/Wp, with a degradation of less than 2% after 1000h DH and 200 TC (IEC 61215 standard). This result is just ahead of the targets set in our roadmap and the levels expected at international level (ITRPV).
Excellent results obtained thanks to developments carried out by giving priority to European partners and suppliers wherever possible.
Ageing tests on modules < 14mg/Wp will be continued up to 3 times the standard requirements to ensure the superior reliability of the solution or to highlight any new degradation phenomena that need to be prevented.
These developments are continuing, with the aim of further reducing the photovoltaic industry's silver consumption to less than 3mg/Wp by 2030.
The results of this study were presented at EUPVSEC 2024 and during the workshop MIW 2024
Figure 1: Silver consumption of photovoltaic panels and comparison of the results obtained by the CEA at INES (at module level) with the anticipations (at cell level) of the ITRPV – Credit: CEA
Figure 2: Mini-demonstrator module using cells metallized with copper-silver pastes and interconnected with copper ribbons, produced by the CEA laboratories at INES
Credit: CEA / Laurence Godart