The economic viability of photovoltaic generation largely turns on two factors: energy conversion efficiency and production cost. Theoretically, stationary solar panels should be able to convert 25 to 30 percent of sunlight into power, but today’s conventional silicon panels rarely achieve better than a 19 percent conversion rate. Now, a Santa Barbara startup company, Solar3D, believes it can optimize PV economics through a three-dimensional design and a few other tweaks to conventional silicon solar cells. “Our original design focused on putting a lens on” solar cells, explained Jim Nelson, Solar3D chief executive officer. Lens channel sunlight from oblique angles onto cells to increase the amount of light converted to power, but they raise the cost of solar panels disproportionately, he said. Taking another tack, Nelson said the company studied the biggest obstacles to achieving a better conversion factor with conventional panels and found them to be twofold. First, there was too much reflection of sunlight occurring. About 30 percent of the sunlight hitting conventional panels simply bounces off. Second, conductors in conventional panels are so far from the cells that many of the electrons knocked off by sunlight are reabsorbed into the cell before they reach a wire to create current. To solve these two problems, according to Nelson, Solar3D reconfigured conventional two-dimensional cells through an etching process that makes them three-dimensional. Rather than being flat, Solar3D cells are effectively concave, with the walls on the sides catching oblique sunrays and bouncing the light back and forth until it knocks electrons loose to create a current. The second modification the company made was to move the conductors closer to where electrons are freed by making the silicon thinner and by running the conductors under the light collectors instead of on top, a feature which also maximizes the energy conversion area. The result, according to Nelson, is that Solar3D has achieved an energy conversion efficiency rate of 25.7 percent at a lower cost than using lens to concentrate light. Nelson said this means that systems employing Solar3D technology promise to achieve shorter payback periods when placed in service. Conventional systems being put in place today, he observed, typically have payback periods ranging between 10 and 15 years. Solar3D systems could pay back in six to nine years, about a 40 percent reduction. With its higher conversion factor, the Solar3D system can generate more power during winter when the sun is low, as well as more power in the morning and late afternoons when the Sun is not at its zenith. The company, according to Nelson, is planning to set up a pilot project by summer of 2013 and begin production after that if its technology works as expected in the field.