Introduction: Wafer Silicon Photovoltaics

PV manufacturers are focused on two things: cost reduction and cell efficiency. There are many different approaches to optimizing these items individually, but technology and manufacturing advancements are tackling cost reduction and cell efficiency as two advantageously intertwined opportunities.

The classical cost reduction efforts via supply chain, scaling and balance-of-systems focus are prevalent in most companies around the world, and continue accelerating.

Technology is driving cost reduction and advancements through effective and innovative ways to increase solar cell efficiencies. Levelized cost-of-energy summaries repeatedly show that as PV power plants scale up, higher cell-efficiency systems are gaining numerous advantages over low and medium cell efficiencies. Constrained space markets have generally favored high-efficiency technologies due to the power demands and limited space for PV installation.

Increasing cell efficiencies through innovative techniques is the focus of tens of millions of dollars of proprietary R&D investment at companies like SunPower as well as at industrial research hubs like the Fraun-hofer Institute for Solar Energy Systems, in Freiburg, Germany. Arguably, the practical limit of modern-day solar technology is about 26 percent, with theoretical limits near 30 percent cell efficiency. Fraunhofer ISE Systems is developing photonic structures, or filters, that leverage more of the full solar spectrum and increase the silicon theoretical efficiency limit from 29 percent upward to ~40 percent. This type of technology would continue to augment the power-generation capability of solar cells.

Els Parton, Robert Mertens and Jef Poortmans of imec have also summarized the challenges for silicon PV in the continuous pursuit of increasing cell efficiencies. They explore and highlight some of the upcoming technology approaches of higher-efficiency solar cells via high lifetime silicon, metalization techniques, passivation methods, innovative doping techniques, back-side contacts and thinner solar cells.

While James Bond may have saved the >90 percent efficient solar technology from the Man with the Golden Gun, the PV manufacturers of the real world innovate while cost-reducing <26 percent cell-efficiency technologies. Work like that done by Fraunhofer ISE Systems, and roadmaps as summarized by Ms. Parton, Mr. Mertens and Mr. Poortmans, will supplement the industry’s investments to drive solar prices down to the point of replacing costly fossil-based energies.

FPV6_Intro_WSPV.pdf