Over the last five years, about 40GW of solar manufacturing capacity has been built and almost all of it has been crystalline silicon (c-Si). Over that time, the alternative to silicon — called thin film — has gone from being “the next big thing” to “highly questionable.” With over 100 thin film companies either sold, merged or just dead, it is legitimate to ask: “Is thin film dead?”
The answer is no. Thin film is not dead; in fact, it will win in the end, and here are seven reasons why:
1. It’s Thin.
This is the reason thin film was attractive to begin with. Thin film materials have a property, called bandgap, which is superior to silicon. Funny as it sounds, silicon just doesn’t like to absorb light. First of all, it only wants to absorb low wavelength light (red and IR), rather than most of the light that comes from the sun. It has the wrong bandgap (which wavelength is absorbed), and it doesn’t even absorb that very well. It takes over 100 microns of material to absorb the light, where thin film takes only 1 micron. Thin film absorbs the right wavelengths, and does it with 100x less material. In an industry where materials cost is important, thinner is much better.
2. Through the Looking Glass.
Thin film uses a less expensive and easier to work with substrate (what the solar cell is built on). While silicon uses silicon (duh), most thin film uses glass. Silicon is more than 10 times more expensive, ($36/m2 vs. $3.60/m2). To repeat: materials costs are very important.
3. Easy as FPD.
Utilizing glass as a substrate allows for unrivaled scale. The flat panel display (FPD) industry, which allows us to watch HDTV at a reasonable price, has scaled glass processing tools to an amazing 50X higher throughput over the last few decades. All that know-how is available to anyone using glass substrates. A single thin film production line can achieve 300 MW output per year vs. the 25 MW standard for c-Si. This scaling advantage is huge when it comes to reducing those non-materials costs such as labor, overhead, and depreciation.
4. CapEx is Why.
High-capacity glass processing tools, beside the impact on cost, also have lower capital intensity. Solar is considered a capital-intensive business, measured by how much it costs to build a factory in $/watt. The “dollar” is the factory capital cost and the “watt” is the yearly output. Silicon factories are very capital intensive, with polysilicon, wafer, solar cell, and panel factories adding up to over $1.40/watt. Thin film, on the other hand, ranges from $0.50 to $1.00/watt, and the 300-MW factory mentioned above would only be $.33/watt, a 4x advantage in capital intensity. The graph below shows the CapEx difference if added capacity were either all c-Si or all thin film. To put the impact in perspective, if solar gets to just a 14 percent penetration of the energy industry, the CapEx difference would amount to over $5 trillion. That is not a typo. That is trillion with a “T.”
Capital intensity is not talked about much yet, but it may become the deciding factor in the growth of the solar industry. Low capital intensity is a huge advantage. Thin film can affordably scale to meet our energy needs.
5. Efficiency (Yes… Efficiency).
Thin film is no longer at an efficiency disadvantage vis-a-vis silicon. Throughout solar history c-Si has had better efficiency, but in late 2013, thin film (CIGS) beat multi-crystalline silicon in laboratory efficiency. This lab result hasn’t transferred to the production floor yet, but this should happen in just a few years. When thin film beats c-Si on performance, the inherent cost advantages will be magnified, and thin film will start its major comeback.
6. Manufacturing Mojo.
Combine these 100X, 10X and 4X cost advantages with high efficiency and you get the lowest manufacturing cost. As recently published (link), Siva Power outlined its thin film cost roadmap, showing CIGS getting to $0.28/watt within four years. That is an unheard-of number for c-Si technology.
7. Déjà Vu All Over Again.
Although silicon previously dominated the solar landscape, thin film leader First Solar emerged and was the first to $1/watt, the first to 1GW production capacity, and became the largest and most profitable solar company in the world. It was done before, and it can be done again. We just need First Solar 2.0. The company that leverages these thin film advantages can not only come back, but lead the solar industry within the decade.
Developments in the past six months indicate that thin film is not only experiencing a revival, it is positioning itself for a run at silicon. The world’s largest solar panel power plant? 290 MW of thin film. Solar charging stations for Tesla in China? Thin film. Record for the world’s highest efficiency solar panel? Thin film. Biggest solar project planned in Africa at 400 MW? Thin film.
Thin film’s best days are yet to come.
Lead image: Finish line via Shutterstock