AstroWatt Exfoliates to Reduce Solar Silicon Wafer Costs

AstroWattlogo AstroWatt, Inc. CEO Dharmesh Jawarani pitched the thin crystalline silicon substrate start-up at Dow Jones Alternative Energy Innovations Fall 2009.
AstroWatt is looking to raise a $10 million to $15 million financing round beginning March 2010.

Based in Austin, Texas USA, early stage photovoltaic (PV) start-up AstroWatt was founded in July 2006 as a:

Developer of a low cost, proprietary process technology for making high efficiency solar cells based on thin crystalline Si material on flexible substrates. The technology uses a fraction of the Si material used in standard crystalline solar cells and can be readily integrated with existing manufacturing processes used in the solar cell industry.

Seed round investors to date include Austin Ventures and New Enterprise Associates, Inc. (which does not list them among their portfolio companies) to the tune of $1.6 million. The company boasts a six person engineering team including CTO (Chief Technology Officer) Leo Mathew.

In his opening, Dr. Jawarani said, “Even today, Solar cell cost is largely dictated by Si (silicon) wafer cost.” For the typical 156 mm (millimeter) or 6 inch square and 200 um (micrometer) thick multicrystalline silicon (mc-Si) solar cell delivering around 3.65 Wp (Watt-peak) at 15% conversion efficiency, Dr. Jawarani cited a silicon wafer costing $3 selling for $5 after cell processing and implying a raw wafer cost of about $0.85 per Wp.

Semiconductor on Metal
AstroWatt has developed a proprietary Semiconductor on Metal (SOMTM) technology for creating thin silicon wafers that can be processed using today’s PV manufacturing tools. After partial processing, a monocrystalline silicon wafer is attached to an inexpensive, flexible 50 um metal foil also acting as the solar cell’s rear contact. Next the foil along with about 25 um of silicon is exfoliated using a cleaving process. By reusing a 600 um wafer for multiple exfoliations, AstroWatt claims “Up to 4X (four times) reduction in Substrate Cost” is possible, and the metal substrate is crucial for wafer handling in existing equipment. AstroWatt also stated the theoretical peak silicon solar cell efficiency can be achieved with a 25 um silicon wafer thickness.

From Dow Jones Alternative Energy Innovations Fall 2009

To date, AstroWatt has processed small size (I assume postage stamp) solar cells using SOM substrates and claims close to 10% efficiency without surface optimizations, anti-reflective coating, or passivation.

From Dow Jones Alternative Energy Innovations Fall 2009

Financial Comparison
AstroWatt believes SOM can lower the wafer or substrate marginal cost from $0.83 today to $0.26 per Wp at a 50 MW scale (MegaWatt) cell production line. As shown in the above slide, notable assumptions include:

  • Conservative $10 million ($0.20 per Watt) adder for SOM to the 50 MW Cell Line Total CAPEX.
  • Each monocrystalline wafer is reused 10 times.

Current Status and Plans
AstroWatt has prototyped four (4) inch silicon, germanium, and gallium arsenide SOM substrates using manual exfoliation. Only silicon solar cells have been processed on the SOM substrates although III-V multijunction solar cells and LED applications are envisioned using the core exfoliation technology. AstroWatt said they have performed hundreds of exfoliations thus far.

AstroWatt’s strategy is to develop the core technology and partner with cell manufacturers to implement SOM Solar Cell production via a licensing model.

With more patents in the works, three (3) AstroWatt patent applications have been published both at WIPO as shown below and the United States Patent and Trademark Office (USPTO):

(WO/2009/143026) METHOD OF FORMING AN ELECTRONIC DEVICE USING A SEPARATION TECHNIQUE

(WO/2009/137610) METHOD OF FORMING AN ELECTRONIC DEVICE INCLUDING REMOVING A DIFFERENTIAL ETCH LAYER

(WO/2009/137604) METHOD OF FORMING AN ELECTRONIC DEVICE USING A SEPARATION-ENHANCING SPECIES

AstroWatt is leveraging technical advisors and resources at the UT Austin (University of Texas at Austin) Microelectronics Research Center where they are a National Nanotechnology Infrastructure Network (NNIN) company to facilitate a capital efficient research model.

Near term, AstroWatt needs to establish a process flow, achieve a 15% efficient solar cell, develop a semi-automated exfoliation tool, and provide first samples to customers to obtain feedback.

From Dow Jones Alternative Energy Innovations Fall 2009

In order to move to the prototype phase, AstroWatt plans to raise a $15 million Series A round in the March to June 2010 timeframe for the next three years of development and commercialization.

During the Q & A, Dr. Jawarani made a point to mention ion implantation a la Silicon Genesis (SiGen) was not a step in the process. Two further questions ensued during the session.

Q: How much do you want to say about how you cleave it?
A: Very little. (laughter)

Q: What’s the method? Is it a standard method?
A: It is a very commonly used method.

The AstroWatt company name has an unwelcome resemblance to AstroPower although I don’t believe there is even a remote connection. In a sign of the social media times, the twitter name astrowatt has already been taken.

One comment

  1. Johny says:

    Below that article you show poly prices of 55$/kg, which translates (if you cut app. 60 wafers out of one kg), to 0.83$/wafer, which is app. 0.2$/watt+0.20$ for wafering makes app. 0.35$-0.40$/watt, and the mentioned above 0.85$/watt.
    It looks like some people still didn’t notice the big change between 2008 and 2009.

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