Dr. Finlay Colville,  Director of Marketing by Coherent Inc.

Dr. Finlay Colville was appointed by Coherent Inc. as Director of Marketing in a team that is solely dedicated to the field of photovoltaics.  Dr Colville has co-authored many articles over the past couple of years, explaining the role of lasers in the solar industry and how lasers can plan play an enabling part in shaping the growth of the solar industry as a whole.  When not flying around the world to solar trade-shows, Finlay can often be found in the crowds at European championship soccer matches involving Scottish clubs, at test match grounds in England watching overseas nations taking on the English cricket team, and at music concerts when some of his favourite bands or singer/songwriters tour the UK.

1. Dr. Colville, the way that the market for solar cells is shaping up, the laser industry can surely look optimistically into the future. Is this optimism justified?

Dr. Finlay Colville:Certainly!  Lasers are fortunate to be well accepted as the preferable technology type for several specific manufacturing steps and do not have to fight to replace alternative technologies.  Therefore, at first glance, any Year-over-Year increase from end-users (or ‘demand’) drives cell production CapEx spend, and often by default, the use of more lasers!  So that’s the first reason for optimism!  The second reason is that there is a general ‘trend’ within the industry which will result in more cell production steps involving lasers, compared to today.  Therefore, the growth in lasers used for solar cell production is likely to experience growth rates higher than those resulting from of the overall industry itself.

2. Will there be developments in laser technology especially for applications in solar cell production?

Dr. Finlay Colville: This is a very interesting point.  Up until now, lasers used for solar applications have largely been developed by leading laser companies for other market sectors; flat panel displays, microelectronics, and materials processing.  This was not completely surprising: it’s only in the past few years that laser sales for solar has increased to a significant level, and most initial process qualification has relied upon an existing, established laser technology / platform to show proof-of-principle.

But this leads to people asking: “Okay – the process seems to work with laser ‘X’.  Now I want to optimize the cell efficiency, yield, and throughput.  I think this needs laser ‘Y’.”  As such, the solar industry is now demanding lasers that have sub-ns pulse-widths, wavelengths from the UV to the IR, high-rep-rates of several hundred kHz, and, of course, high productivity returns for the investment.

It’s probably too early to say that the solar industry is exclusively driving specific laser technology developments, but it is certainly a very strong voice.  The one application we can point to is patterning on Thin-Film solar panels (where lasers are used to perform the cell isolation and interconnection – or put simply – dividing a large solar panel into discrete low-current strips or cells across the panels).  This application demands the combination of short ns pulse-widths, high repetition rates in excess of 50 kHz, and excellent pulse-to-pulse repeatability.

3. What are the respective differences in outlook for the two separate technologies: crystalline solar cells and thin film modules? And which technology is better suited for the use of lasers?

Dr. Finlay Colville: The second part of the question is easier to answer.  Both c-Si and Thin-Film technologies are equally well suited for lasers to be used within the manufacturing stages.  The difference is simply in the types of processes (or laser applications) for each technology.  And the rates at which c-Si and Thin-Film will grow relative to one another.  Thin-Film may have the edge, as any new process within c-Si often requires other new inline steps in the production lines to be qualified as turn-key-ready.

But today lasers are just getting into c-Si production lines, and there are many different possibilities for laser processing on the front and back surfaces, as well as drilling tiny vias through the bulk c-Si itself.  In general, c-Si module production has more steps than for Thin-Film, and more varieties of cell types are possible.  This gives rise to a wider range of laser processes in c-Si compared to Thin-Film.  Thin-Film panel production is a much simpler process involving deposition/scribing/laminating.  The good news for laser suppliers is that the scribing process is accepted as a laser-preferred application, and what’s more - it’s a laser-unit-hungry demand.  One Thin-Film production line (typically 5 MW to 50 MW) can use roughly anywhere between 3 to 12 lasers alone!

4. Is Coherent focussing their activities on any one these technologies?

Dr. Finlay Colville: Coherent is in the position of having such a wide range of lasers and technologies.  And many of our lasers have been developed for the microelectronics and flat panel display markets, where we are a dominant player.  As such, we have near-optimum lasers for almost all possible solar applications in each of c-Si and Thin-Film.  With the solar industry still in very high-growth mode, and consisting of c-Si cells, various Thin-Film types, and ‘Gen-3’ technologies, it’s probably a bit early to pick one of these and focus all efforts there.  Nevertheless, we are very pro-active when it comes to new product developments. In other words, we take a close look at the specific features of a new product to see how these can bring new opportunities in growth markets, such as the solar industry. A particular example of this approach is the recently released TaliskerTM laser. This provides turn-key ultra-short ps pulse-width operation, with industrial turn-key reliability and the option of high-power UV output at 355 nm. These are all things that solar cell producers have told us that they need to get lasers involved in more cell production steps. That’s why it’s in everybody’s interests when we go to the solar industry to show exactly what this new laser can do. And after identifying the potential of involving a specific laser in a particular step, we’ll then look to see how we can customize it to deliver the exact parameters that are needed. For example, we recently modified one of our new laser platforms - the MatrixTM - to provide the optimum combination of parameters for Thin-Film patterning.
Getting back to your question, we’re not focussing our activities on a specific technology. But We we are very happy to apply our products to meet laser demands in any of them right now.

5. How large is the market for lasers in solar cell production? What are the numbers now and how will this develop in the future?

Dr. Finlay Colville: As a very rough guideline for laser-sources only, I’d put a ballpark figure in the range of $100M for the calendar year 2008, still including many pilot-lines and R&D equipment spend, but there’s been no detailed market review published to date on this so far.  In terms of how this will develop in the future?  Well, in the short-term, one could imagine this growing at 40% CAGR’s.  In the long-term, it’s the stuff of crystal-ball reading.  This will depend on just how much the solar industry competes with other established or ‘carbon-free’ renewable energy types, and indeed whether the oil industry starts to react to alternative energies as these alternative sources start to take away some of its market share.  And then we have the balance between c-Si, Thin-Film, or ‘Gen 3’ technologies like organics.  And there are yet even more possible ‘wildcards’ that could come into play and disrupt this.

6. How much laser technology is still in the R&D stage and how much has already found its way into the production environment?

Dr. Finlay Colville: That’s a good question.  As a percentage, only a small amount of R&D has found its way into mainstream production line tooling.  The big one that jumps out is the Thin-Film patterning on a:Si and CdTe panels.  To a lesser extent, we have laser edge isolation on the c-Si side.  But so long as the roadmap of solar is being driven by increased cell efficiency, higher production yields, and lower $/W costings downsteam, there will continue to be more new ideas from the research labs, more advanced cell concepts like the RISE cell from the ISFH, and as a result, more new possible applications where lasers are an enabling part.

7. Dr. Colville, what is your prediction for the next five years? Will crystalline cell technology continue to clearly dominate? Can thin film technology make some ground in the future?

Dr. Finlay Colville: Indeed, much is written on this very subject on a weekly basis.  The first thing to mention is that almost every technology will experience growth at double-digit rates, over the next few years.  So in that respect, each is a winner in its own right.

There is a strong momentum behind the c-Si equipment value chain, and the significant investments at the raw material level will ensure that c-Si capacity expansions do continue as planned.  There is an extensive roadmap addressing incremental decreases in the $/W of final installation costs too, at almost every level of the value-chain.

Thin-Film does appear to be about to go through a transitional phase – particularly with a:Si.  There has been an enormous growth in CapEx spend with a:Si players, and the next few years will be seeing many of these investments coming through to actual production output numbers.  Amorphous-silicon Thin-Films also need to undergo their predicted transition from single-junction to tandem-junction (in particular to a:Si/mc-Si stacks) to boost a:Si efficiency from ~ 6 to 10%.  CdTe by virtue of one established front-line player is almost certainly going to continue to be a winner, and it’s not clear yet if other players will contribute to this sub-segment at the same growth rates.  CIGS Thin-Film panels are yet to match their promise, and some analysts are viewing this technology now as a wildcard – if it takes off, it could be big!  Very big!

Dr. Finlay Colville thank you for the interview.

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