Process identified to reduce PV costs

MENLO PARK, USA: Polysilicon is the backbone of both the semiconductor industry and the photovoltaic business, providing the basic substrate upon which electrical circuits are built and sunlight is captured and converted to electricity. The purity of silicon used to make solar wafers can be considerably lower than the electronic grade silicon used to make semiconductors.

SRI Consulting (SRIC) released its techno-economic report Polysilicon for Solar Wafers that provides the process design and manufacturing economics for three of the dominant commercial processes.

As of the third quarter 2009, global demand for polysilicon was approximately 50 thousand metric tons per year, split nearly evenly between demand for semiconductors and solar applications.

Recently, silicon based photovoltaic grade producers have learned how to produce the photovoltaic cells directly from polysilicon. Eliminating the costly step of first converting polysilicon to higher purity single crystal silicon allows for the use of lower cost manufacturing technologies.

SRIC senior consultant and author Anthony Pavone commented: “The knowledge of competitive manufacturing costs is important because the business has reached overcapacity. The global economic recession of 2008-2009 resulted in flat polysilicon demand, yet capacity increased due to government subsidy.” Pavone continued, “Polysilicon producers who can’'t compete on cost will be driven out of business.”

The Polysilicon for Solar Wafers report compares the process design and manufacturing economics for Siemens reactors, fluidized bed reactors, and directional solidification furnaces. A head-to-head comparison of capital and production costs of the three processes is presented using a common engineering methodology; consistent feedstock, product pricing, and design basis for a generic 5,000 metric ton per year grass roots plant.

To eliminate the confusion associated with two of the three processes requiring an up-front gas plant, each polysilicon design purchased its feedstock at prevailing high volume contract prices.