Dual-Glass PV Module Penetration Rises, Driving Thin-Glass Electrode Demand

Conventional modules use a backsheet for encapsulation, while dual-glass modules replace the backsheet with two panes of glass. This delivers better moisture barrier and weather resistance and a longer service life, making them particularly suited to distributed rooftops and harsh environments with high humidity or salt fog. In recent years leading module makers have expanded dual-glass capacity one after another, and in 2018 dual-glass penetration rose noticeably. With two panes per module, photovoltaic glass consumption nearly doubles, thin glass demand grows accordingly, and line configurations adjust. Dual-glass modules generally carry longer warranties, and improvements in yield and cost have made them increasingly accepted in utility-scale projects; dual-glass also raises module power density and system yield, which appeals to plant investors.

The difficulty of melting thin glass

Dual-glass modules generally use thin glass around two millimeters, with tighter requirements on thickness uniformity, flatness and defect control than conventional PV glass, and thickness tolerances measured in fractions of a millimeter. Thin sheets have low thermal inertia during forming, so any fluctuation in the furnace glass melt temperature is amplified, directly affecting yield; thin glass is also more sensitive to refining, and residual bubbles lead directly to module failure. Electric boosting responds quickly and adjusts finely, and second-scale response absorbs load fluctuations, making it a key means of stabilizing thin-glass furnaces, with the molybdenum electrodes immersed in the melt acting as the energy valve of that system. In thin-glass furnaces the melting and forming sections are more tightly coupled, and temperature disturbances are amplified into thickness deviation.

Three trends in line configuration

• Deep electric boosting: thin-glass furnaces run a higher electric heat share than conventional PV lines, with more molybdenum electrode sets;
• High-purity electrodes: high-purity molybdenum electrodes reduce the risk of corrosion products affecting glass transmittance;
• Zoned fine tuning and online monitoring: multiple electrode sets are adjusted independently, with electrode resistance and life records kept to support continuous production;
• Water-cooled sealing: thin-glass furnaces have many ports, so electrode sealing structures must be reliably leak-tight.

Supply chain linkages

Following the thread of glass melting, product-level parameters center on electrode specifications for glass electric melting furnaces.

Dual-glass penetration transmits competition at the module end to the glass end and further to the furnace end: glass makers are laying out thin-sheet lines, electrode suppliers are winning matching orders, and collaborative development between glass makers and module factories around thin-sheet specifications is increasing; the trade-off between furnace investment and yield is also a key calculation for glass makers; and the cost-effectiveness of dual-glass in different applications is still being reassessed, with the pace of penetration fluctuating with the price ratio of glass to backsheet. The WeiBeam.com technical team's analysis is that whatever the outcome of the route debate, the trend toward higher quality and thinner photovoltaic glass is established, electrode demand in this segment has a basis for long-term steady growth, and iterative specification upgrades toward thinner sheets and higher transmittance will continue to raise the quality bar for electrodes.