July 18, 2017
Natcore is in the final stages of developing an all-back-contact cell in which the metallization is a multilayered aluminum foil, as opposed to the standard interdigitated back contact (IBC) approach. The use of a multilayer structure, combined with the extremely low cost of aluminum, provides significant cost savings:
? We currently estimate that total metal cost for a 156 mm cell made with Natcore’s approach would be under $0.01. This is estimated from prices of commercially available aluminum-polymer- aluminum laminatesi. Assuming a laminate cost of $2.70 per kilogram, the ~3.1 g of laminate used for a 156 mm cell would cost approximately 0.8 ¢/cell. About 0.5 ¢/cell of that cost is due to the cost of aluminumii.
? Standard industry cells (not all-back-contact) utilize screen printed silver pastes. According to the International Technology Roadmap for Photovoltaicsiii, current cells use about 100mg of silver per cell, and that number is projected to drop to about 50mg per cell by 2024. Some important considerations:
o 100mg per cell at today’s silver price ($0.52/gramiv) costs 5.2 ¢/cell.
o These prices are only for the actual silver metal price, and thus do not include the mark-up
cost of the pastes that are used, or the cost of any processing to apply silver to the cell. o Even though silver usage per cell is expected to drop in the future, as the volume of the
solar industry expands it will eventually drive up silver prices.
o The reduction in silver usage will likely be achieved with other technologies (plating,
SmartWire Connection Technology (SWCT)). However, there is some cost added back with these approaches.
? Interdigitated back contact cells have higher efficiency but typically require even more silver than standard cells.
o A 156 mm cell using silver metallization would require about 500 mg per cellv to achieve the same resistance contribution as estimated for our foil cell
o The associated silver cost is therefore about 26 ¢/cell.
Efficiency: Our best laboratory cells are just under 21% efficient. However, these cells are limited by aspects of the laboratory process such as the type of base contact used—not aspects that are integral to our process. The most important take-away is that the cell design is a fully passivated-contact design, and thus capable of efficiencies >24%.
