Jason Eckstein

Solar Modules: Good enough is better than best for frontsheet materials

Graphic of the WeekIn a race to improve margins and expand market share, solar manufacturers are seeking to jettison all unnecessary costs from their photovoltaic (PV) modules. The most stubborn of these costs generally derive from non-active materials, such as frontsheets, encapsulants, and backsheets, which can contribute between 25% and 40% to overall module costs.

In a recent report, Lux Research surveyed the field of emerging non-active material technologies for flat plate PV modules in order to assess which have the most potential for adoption. This week’s graphic highlights the report’s take on alternative frontsheet technologies. In order to determine the break even cost of these materials – the cost at which a manufacturer maintains or increases its profitability – Lux Research calculated the relative impact on module efficiency they offer compared to rolled, patterned low‐iron glass, the incumbent material for crystalline silicon (x-Si) modules.

The graphic’s left side lists the relative efficiency impact for all the alternatives to rolled, patterned low-iron glass considered. Clearly, a number of fluoropolymer materials offer lower frontside reflectance and boost module efficiency by as much as 2.8% in the case of FEP. However, most of these materials are prohibitively expensive to warrant a switch. The graphics right side illustrates the % difference between break‐even cost and the current material cost. Again, it shows viable, field‐tested fluoropolymers, like ETFE, cost about 20% more than its break‐even value of $14/m².

Three other materials, however, offer an attractive value proposition from a price perspective. Low‐iron float glass is the most viable drop in replacement for rolled glass. Counter intuitively, it offers a modest overall price advantage at a cost of $9/m² over rolled glass despite slightly lower transmittance. Consequently, as rolled glass has increased in price, suppliers have begun offering float glasses of equal quality, and x-Si players like SolarWorld have begun incorporating the cheaper alternative into their modules.

On the fluoropolymer side, sheets based on transparent PVDF and Tedlar also provide dramatic cost/performance advantages over glass – each with well over $1/ m² of room to increase pricing and remain competitive. However, concerns regarding the long‐term field performance of such materials remain a key hurdle to adoption.