A 126 mm stainless steel substrate sample depicting the flexibility of the stainless steel wafer format and development of the backside contact Chrome Molly process (first Layer below). This work is being done to demonstrate the adaptation of high-rate deposition techniques utilizing HDD equipment. 

BY Sarah Jeong (pved1@infothe.com)

First of all, please introduce XsunX to our readers.

XsunX is an Aliso Viejo, Calif., U.S.A.-based company that is combining its Thin-film Photovoltaic (TFPV) process knowledge and processes with magnetic media thin-film manufacturing technologies used by the hard disc drive industry to mass produce high efficiency, low cost solar cells.

Recently, XsunX completed the first stage of CIGS thin-film solar device development. Please share with us the technical breakthroughs XsunX has achieved so far.

XsunX has reached several significant milestones in 2010 that each increases the rate with which the company can develop this new technology towards initial baseline commercialization goals.

The core aspect to our technology development effort is the successful combination of small area co-evaporation techniques with high rate material handling and systems management technologies developed for the hard disk industry. The fundamental breakthrough objective for XsunX is the development of a co-evaporation tool or system that will contain many co-evaporation tools allowing for simultaneous mass production of individual, or discrete, CIGS solar cells. Our key ‘breakthrough’ has been the systematic development of a co-evaporation toolset that works efficiently with our process recipes to achieve the desired results. There is an interactive aspect to the materials used to manufacture the CIGS solar cell and the tools or systems used to deliver these materials in precise ways. Our milestones are based on successfully testing, adjusting, and achieving the desired results and include the completion of the first working device samples in December 2009, and then in March 2010 the completion of the engineering for the manufacture of our first fully integrated co-evaporation chamber. This development was seen as crucial to both the equipment and process technology side because it combined several operations that had been developed separately into one unified process.

XsunX is integrating the mature Hard Disk Drive (HDD) technology into CIGS expertise. How did this technology affect your technical achievement?

For some time now, the use of co-evaporation techniques to produce the highest quality CIGS devices has been the standard. Unfortunately, co-evaporation processes have proven very difficult to scale for use in large area manufacturing techniques utilized by most CIGS developers or manufacturers. Our objective was to keep the process area small and eliminate the numerous variables that are introduced through efforts to scale the process. This, however, required that we come up with a method to provide commercial quantities to compensate for small area individual cell fabrication. This is where the use of hard disk manufacturing techniques provides us with proven high rate material handling techniques and systems design that has spent years focusing on small area processes while driving costs down and product quality up.

Any difficulties in the process of adapting HDD technology to the manufacturing program?

Before we began the actual development effort, we spent numerous months reviewing the possibilities and comparing the potential. What we found was that it was very doable; however, we realized that it would require a development and engineering process that initially would progress incrementally. We’ve developed a very thorough work plan and as our work has progressed we’ve been able to increase the rate with which we are achieving certain milestones under the plan. Obviously, you always want things to move as quickly as possible but to date we have not encountered any obstacles that we were not able to overcome.

What makes XsunX’s Thin-film Photovoltaic (TFPV) process unique and favorable compared to others?

This approach is a technology that bridges the gap between inexpensive thin film and high efficiency silicon wafer technologies to produce solar cells for multiple market segments and a wide variety of applications. The goal is better engineering and not necessarily the development of new science. We are essentially taking well-known science and manufacturing methods and combining these to produce a product that reduces the structure defects caused by large-area processing techniques. This, in turn, produces higher conversion efficiencies, and utilizing high-rate material processing techniques from the HDD industry to then compensate for the needed volume under commercial production. The result we believe will be manufacturing systems that require significantly less space, cost less per MW, provide proven commercial production cycle uptime, and produce a CIGS solar cell that provides conversion efficiencies approaching that of polysilicon at about half the cost.

There are many optimistic opinions on the growth of the global solar industry in 2010 after having been through the worst stage of the global economic crisis. Are you one of the optimists? What are your thoughts on the global solar market in 2010?

XsunX is definitely standing in the optimistic column. Over the past several years, a very solid worldwide foundation has been built to support solar adoption policy. All technologies have an adoption cycle and solar’s will occur over the next 1 to 2 decades. There will not be an overnight changing of the standards from coal to solar. There’s just too large an industry associated with fuel-based power production, but as the costs for fuel-based power continue to rise and the technological advancements for solar continue to drive costs down, I believe we will see broader and more rapid adoption curves.

Please share your view on the U.S. government policies and subsidies on which the solar industry strongly depends.

As the U.S. inches closer to adopting green technology on a mass scale, it’s important to remember that just one policy is not going to fuel widespread adoption rather a combination of policies including feed-in tariffs, rebates, renewable energy credits and net metering. A renewable electrical standard, or RES, would also be a unifying attempt to seriously jump start the renewable sector.

What do you think are needed to reach grid parity in solar PV?

In addition to the tremendous support and opportunities offered by the U.S. government, there are numerous other policy measures that have already been enacted and are waiting implementation around the world. What we are seeing in the early stages of 2010 is an inflection point, where broad support to begin implementation of previously enacted policy is occurring in the U.S., China, and other regions. The benefit to the solar sector is as meaningful adoption occurs it helps to further reduce the cost of underlying technologies and help to continue to move the sector toward economic parity with traditional power and energy solutions. 

Lastly, where do you see XsunX in the CIGS thin-film market and in the global solar industry as a whole in 5 years from now?

Currently, over 80% of the solar market uses silicon wafers to manufacture solar modules. We believe that by making a thin-film CIGS wafer on a stainless steel substrate, we may be able to provide or produce an alternative technology to silicon on a mass scale. The thin-film CIGS wafer would be used as a substitute to silicon wafers in the assembly process of a solar module. Additional market applications would include: utility-scale solar fields; BIPV products; residential markets; and consumer products. We believe the replacement of silicon wafers will be the first application where our technology is adopted. In five years, we plan to have improved the conversion efficiencies of our thin films to match those offered by polysilicon, and to increase the size of our solar cells from 125 mm square to 210 mm square. These initiatives are designed to further reduce per watt manufacturing costs and maintain a competitive advantage for our technology.

Sarah Jeong is Editor of InterPV. Send your comments to pved1@infothe.com.

For more information, please send your e-mails to pved@infothe.com.

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