The Future of Thin Film PV

by James Groelinger and Alan Delahoy

On November 21, BP Solar announced its exit from thin film manufacturing. While some viewed this as a harsh blow to thin films generally, we didnt. We wrote at the time, The marketplace is a cruel discriminator – and technologies dont win out simply because they perform well technically. They also must perform well commercially. At the same time that BP is supporting its withdrawal, Energy Photovoltaics, Inc. (EPV) is finding strong commercial demand and improving manufacturing economics.

To be successful, photovoltaics must become more than a technically interesting energy producer that, with subsidies, makes sense. Photovoltaics must be about energy and economics. On the energy side, both the consumption and delivery must make sense. The delivery side is thought to be obvious, but new evidence shows the strength of thin films. Under most real world conditions, amorphous silicon (a-Si) produces more energy per-installed-watt than crystalline technologies. At the PV in Europe conference in Rome, for example, Jardine reported, Double junction amorphous silicon products have been shown to give the greatest energy yields per manufacturers declared kW peak. In conjunction with the lower manufacturing cost of thin film products, this leads to a key to market penetration – the lowest cost per kWh.

Theres growing awareness that the manufacture of PV modules is energy intensive. Over half of the energy consumed in making wafer-based modules is used to produce the wafers themselves. The published range of total energy requirements to produce crystalline silicon modules is 20-100 MJ/Wp. In contrast, we (and others) calculate the specific energy required to produce frameless a-Si thin film modules at 12-15 MJ/Wp – for CIGS thin-film modules a figure of 11 MJ/Wp has been published.

Given the increasing attention to carbon emissions, the growth of photovoltaics will only be a benefit if the industry is a net energy producer; otherwise, were simply using carbon-emitting kWh to produce fewer non-carbon-emitting kWh. To achieve a net energy contribution at a manufacturing growth rate of 30 percent per annum, the specific energy must be less than 23 MJ/Wp, and if a positive energy return from a new factory is desired in fewer than 10 years, less than 18 MJ/Wp is required. This positions thin films as the only option. We expect considerations such as this to become increasingly important in the formulation of energy policies.

Thin film products are aesthetically attractive, uniquely suited for building integration and innovative semi-transparent applications. With improved marketing, thin films are certain to prosper in the long run.

This article first appeared on SolarAccess.com as part of RE Outlook 2003, visions of Renewable Energy’s year ahead, a series of articles that features articles by more than 25 industry experts.