Reexamining Silver In Photovoltiacs
Published: March 07, 2012 Category: Advanced Materials Renewable Energy

Thin-film PV: TFPV is growing more rapidly than c-Si PV, and NanoMarkets expects TFPV to account for about one-fourth of the total PV market (on an energy generation basis) by the end of the forecast period. As noted above, from the perspective of silver suppliers, this shift is not especially good news, because TFPV uses much less silver than c-Si PV.

• First, we note that tabbing is virtually nonexistent in TFPV, since nearly all cells are monolithically interconnected on a common substrate.

• The front electrodes in TFPV are typically made using TCOs rather than fine silver fingers, although silver grids are sometimes applied on top of the transparent electrodes. While the quantities of silver used for TFPV are smaller than those used for c-Si PV, silver ink manufacturers have developed products specifically for these fine silver grids, which are both finer than those used in c-Si PV front electrodes and more difficult to adhere because of the underlying transparent conductors. Special ink formulations are produced to address these challenges.

• In back electrodes today, the largest TFPV technology, cadmium telluride (CdTe) PV, forgoes silver entirely in favor of a carbon-based paste containing copper.  Copper-indium-gallium-(di)selenide (CIGS) PV, on the other hand, uses molybdenum for the back electrode for most cells, for ease of sputtering directly on glass substrates and for good adhesion to the CIGS layer. But back electrodes in TFPV often act as both electrodes and reflectors, to send unabsorbed light back through the cell’s active layer for a second chance at absorption. Silver's superior reflectivity combined with its high conductivity makes it a natural choice for this role, and it has been used extensively. However, the cost pressures on both CIGS and CdTe PV have pushed strongly for substitution of other metals—mainly aluminum—for the reflector. 

The importance of nanosilver to opportunities in the PV industry: As changes in the PV industry occur, namely the shift toward increasing TFPV, there is an important sub-trend that could at least partially offset the decline in conventional silver paste usage elsewhere in PV.  Specifically, NanoMarkets believes that PV could be an important, and higher-margin, addressable market for nanosilver-based transparent conductive front electrodes.

The emergence of flexible PV applications—key to growth in organic PV (OPV), dye-sensitized solar cell (DSC) PV, and CIGS PV—will be particularly important to nanosilver-based transparent formulations, which carry the promise of improved flexibility at lower cost than conventional transparent conductive materials like ITO and the other TCOs that are currently used. Nanosilver-based transparent coatings could also enable reductions in manufacturing costs for production of low-end/low-cost “disposable” PV cells for use in the growing ubiquitous printed electronics industry.

None of these opportunities should detract from the basic fact that opportunities for silver material firms in the PV industry are going to be a lot scarcer than they were in the past few years. NanoMarkets believes that sales of silver materials, mostly in the form of printing pastes and inks, to the PV industry are in slow but steady decline and will remain so for the whole of the period considered in this report.

The decline in silver consumption will not be precipitous; firms that are already established in the PV sector will not see their PV businesses disappear overnight. However, it seems clear that silver firms can no longer count on the PV sector to provide new business revenues simply based on organic growth, and it also seems likely that materials suppliers will be required to dedicate more marketing money to the PV space.  Unless they can prove significant performance advantages or vastly lowered cost—unlikely given the high price of silver—it is likely that margins are going to decline for silver firms targeting the PV space.

NanoMarkets believes that capitalizing on the opportunities will require a serious rethinking of how money is going to be made in silver materials for PV applications.  A more active business development program is required—one that is designed to convince PV players that costs can be reduced without turning to cheaper, non-silver alternatives—and this case will be a difficult one to make.

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