SunPower Discovers Surface Polarization Effect in Solar Cells

August 22, 2005 by Jeff Shepard

SunPower Corp. (Sunnyvale, CA), a silicon solar-cell company and a subsidiary of Cypress Semiconductor Corp., announced the discovery of a new performance effect observed in high-efficiency silicon solar cells, "surface polarization," which creates the non-destructive and reversible accumulation of static charge on the surface of high-efficiency solar cells, such as the company's all-back-contact A-300.

Surface polarization occurs when minute amounts of electrical current leak through the face of the solar cell and accumulate on the surface. Current leakage of this sort is present in all solar systems, but will accumulate or dissipate on the solar cells' surface depending on system grounding polarity and configuration. The presence or absence of surface charge can decrease or increase solar cell current generation in a fashion analogous to the switching of a programmable memory transistor.

SunPower found that electricity production in systems using high-efficiency solar cells could be significantly decreased or increased by varying the system wiring and grounding configurations, and that these performance changes were relatively rapid and completely reversible. As the result of their discovery, SunPower scientists have developed and applied for patents on new solar cell and system designs that eliminate surface polarization.

SunPower founder and CTO Dick Swanson noted, "We believe that the surface polarization effect will be seen in many types of high-efficiency, crystalline solar cells. We are pleased that our research and development team discovered and characterized surface polarization, and subsequently developed practical measures to eliminate this effect in real-world photovoltaic system configurations."