Eric Wesoff | September 8, 2008 at 4:52 AM 1 Comment

CPV, Pt. 3: Solar Cells for High-Concentration Photovoltaics

Part One and Part Two of this CPV series covered high- and low-concentration PV systems, respectively. Part Three follows here and is devoted to firms developing and building the high-efficiency semiconductor cells that perform the actual solar power conversion.

With a genesis in the space satellite industry, multi-junction compound semiconductor cells from the III-V groups are starting to see VC investment and offer a bit of a challenge to the existing Emcore-Spectrolab-Azur triple-junction oligopoly.

Startups building triple-junction cells like Cyrium, Solar Junction and QuantaSol are a natural for venture capital investors, even those new to cleantech and solar. They are compound semiconductor plays, some are fabless, and VCs have domain experience in these sectors.

We expect to see Spectrolab and Emcore challenged not only by these VC-funded startups but also by LED and laser companies with experience in MOVPE and these material sets.

Here’s the list (which includes a Ge substrate manufacturer and a thin-film Ge company as well):

Aonex: Aonex, owned by AmberWave, with technology from the Atwater group at Caltech, builds a triple junction cell with a silicon solar subcell. Here’s the patent. And here’s a paper on their GaInP/GaAs dual junction solar cells on Ge/Si epitaxial templates.

Azur Space: German-based III-V and Si solar cell vendor with a long history of supplying space applications and, more recently, terrestrial CPV applications. Azur’s GaAs cells are manufactured by MOVPE on germanium substrates.

Cesi Ricerca: Developing III-V solar cells for CPV.

Cyrium: Quantum dot-based triple-junction solar cell startup with VC funding from the Quercus Trust, et al. Here’s a link to a relevant patent awarded to the company and its CTO, Simon Fafard.

Emcore: Emcore is a publicly traded, vertically integrated supplier of III-V solar cells as well as CPV systems and is contemplating an IPO for its solar unit in 2009. (See Part One of this series for details on its systems.) Emcore’s cells are said to sell for less than Spectrolab’s cells. It claims to be shipping more than $1 million in solar cells in the third quarter.

IQE: AIM-listed firm providing wafer outsourcing including InGaAsP and InGaN epi wafers.

Microlink Devices: Received $3.2 million from the DOE SAI PV Module Incubator program for multijunction solar cells. Microlink claim that its MOCVD technology and unique processing steps minimizes the amount of GaAs used in the solar cells.

QuantaSol: “Strain-Balanced Quantum Well� triple-junction PV cells from this U.K.-based, VC-funded startup with technology developed at Imperial College London. QuantaSol claims that the spectral response of an SB-QWPV cell can be tuned to maximize conversion efficiency under a “wide range of radiation spectra by varying composition and thickness of the III-V semiconductor nano-layers in the active region of the solar cell.�

Solapoint: High-efficiency GaAs solar cell wafer manufacturing foundry service.

Solar Junction: III-V materials startup Solar Junction CEO Jim Weldon and VP Craig Stauffer confirmed that their funding was “north of $3 million,� the company’s goal is to create very high-efficiency, triple-junction cells for CPV systems, and that the “secret is in the EPI.� NEA is an investor.

Spectrolab: Spectrolab has shipped about 4 MW of CPV cells to date and is moving from 100-mm to 150-mm substrates. Spectrolab has won one of the largest terrestrial III-V solar cell orders from Solar Systems with a claimed 350 MW purchase worth over $93 million. Spectrolab also signed a supply contract with OPEL for 10 MW of cells to be delivered in 2008. It is estimated that Spectrolab’s cells currently cost its customers around $0.90 per watt of power generated.

Spire: Spire has MOCVD capabilities to provide GaAs epi materials.

Sylarus: Sylarus is a startup that claims to be a source for the Ge substrates used by Emcore and Spectrolab in its cells. The company is producing 6-inch germanium wafers.

VPEC Asia: GaAs epi-wafers.

Wakonda: “Virtual Single Crystal� high-efficiency, thin-film solar cells using III-V semiconductors on flexible metal foils. Wakonda claims to be able to produce a Ge film on a flexible metal substrate to replace expensive Ge crystal wafer substrate. The company raised a $9.5 million round A from ATV, General Catalyst, Polaris, Applied Ventures and MGEF. Here’s a link to one of Wakonda’s patents.

Click here to continue to Part Four: Concentrated Photovoltaic Poetry Corner With Sunrgi.