Most photovoltaics are made by depositing semiconducting materials on a sheet. The photovoltaic elements on the surface absorb most of the photons there. Solar3D is taking that idea and setting it on its head by attempting to etch a three-dimensional photovoltaic surface into silicon where light collected on the module surface is directed into a cell where photons can bounce around until fully absorbed by the device. And the company is now preparing to develop its first prototypes.
Usually when light hits the surface some photons are absorbed and some bounce off. “Up to 30 percent of incident sunlight is currently reflected off the surface of conventional solar cells, and more is lost inside the solar cell materials,” Solar3D said in a press release.
Some silicon-based photovoltaics try to compensate for this by creating irregular microscopic surfaces which can absorb incident light reflected by the initial contact with the cell. But Solar3D aims to increase the efficiency by capturing all the sunlight within structures etched into silicon, rather than into its surface.
“It will be a sheet application, in which we have a sheet of silicon, covered with an optical element made of silicon dioxide (or similar material). The photovoltaic structure will be etched into the silicon,” said Solar3D CEO Jim Nelson. “It will all be channeled but the silicon will still only be able to use what it can use. We will be subject to the 29 percent theoretical maximum efficiency that silicon has, but we hope to approach that number.”
You won’t be able to see the individual photovoltaic structures with the naked eye. “It will be a small cell but the level of detail in the cells will be made within plus or minus 1 micron. Furthermore the repetitive period in the construction of the cell will be measured in low double-digit microns,” Nelson said.
The company hopes to produce the first prototypes by the end of 2011. “We have completed the design of the prototype, so all of the elements are designed—though subject to adjustment in the construction period,”Nelson said. “We have done extensive modeling.” The company’s been using software models to develop conceptual prototypes for a while now, since at least last December.
“We have designed our Solar Cell with high efficiency in mind, and then adjusted it to work on traditional, low-cost manufacturing,” Nelson said. “Our anticipation with that [is] we will use high-speed semiconductor machines when we begin producing in volume,” he said.
It will be some time before solar panels are installed that use the new technology. At this point, since Solar3D is still in the research phase, it hasn’t applied for federal financing through the SunShot Initiative, according to Nelson. “We have not approached them for financing yet. When we have proven ourselves…we will probably talk to them about a grant to create the production prototype with a fabrication partner next year.”