Fraunhofer reaches back-contact Si solar cell efficiencies over 20% using RASIRC Steamer

The Fraunhofer Institute for Solar Energy Systems (ISE) recently found RASIRC steamers to yield 20.2% efficiency in the production of MWT and PERC back-contact silicon solar cells. RASIRC is a steam purification company generating ultra high purity steam from DI water.

May 26, 2011 — The Fraunhofer Institute for Solar Energy Systems (ISE) Photovoltaic Technology Evaluation Center (PV-TEC) recently found RASIRC steamers helped yield 20.2% efficiency in the production of MWT and PERC back-contact silicon solar cells. RASIRC is a steam purification company generating ultra high purity steam from DI water.

Fraunhofer used ultrapure water vapor to fab metal wrap through (MWT) and passivated emitter and rear cell (PERC) solar cells. Fraunhofer ran the Steamer in continuous unattended 24/7 operation. The RASIRC Steamer’s nonporous membrane removes volatiles, ionic contaminants (IC), and other impurities from steam generated from DI water. This increases solar cell fab yields because defect-inducing metals, hydrocarbons, and particles are rejected; steam purity is in the parts per trillion (ppt). Defects can absorb solar energy before it reaches contacts on the solar cell, lowering efficiency.

Click to EnlargeRASIRC steamers can replace pyrolytic torches, avoiding thermal build-up from increased flow rate. The steam generators also claim better safety, since hydrogen and oxygen are eliminated from oxidation and the system’s operating temperature is lower. It handles a range of pressures and flow rates.

MWT: External front-contacts are transferred to the backside of the solar cell, allowing more sunlight to hit the solar cell surface.

PERC: The solar cell backside reflection is optimized, and the rear cell surface passivated. The screen-printed aluminum back-contact is connected to the p-type silicon material using local laser alloying (Laser Fired Contact [LFC]).

Learn more about RASIRC products at the 37th IEEE Photovoltaic Specialist Conference, Seattle, WA, June 19-24, 2011, Booth 316.

RASIRC products purify and deliver ultra-pure liquids and gases. RASIRC can generate ultra-high-purity (UHP) steam from de-ionized (DI) water. Learn more at www.rasirc.com.

Also read: Fraunhofer develops 23.4% efficient n-type Si solar cell

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