Solar’s seen a revolution of sorts over the past few years, from an obscure, expensive technology to a technology that’s the fastest growing family of energy technologies in the world that, while still expensive, is becoming cheaper everyday. That’s being fueled by a number of factors, including innovation, cost-drops and efficiency increases. But to continue the trend efforts like the SunShot Initiative must continue to drive such costs down. 

During the Department of Energy’s SunShot Grand Challenge Summit and Technology Forum in Denver industry experts discussed how the industry has changed and the changes to come as solar becomes a major global part of the power supply.  

Richard Swanson, president emeritus of and founder SunPower Corp., has a long history with photovoltaics stretching back to the 1970s. He watched as the technology has grown. “The efficiency of crystalline silicon continues to increase. This is a relatively recent phenomenon,” he said. “You plot the module efficiency of commercial modules form about 1983 to 1998 or so and it was almost constant. There was essentially no change.…That's all changed. And everybody understands the importance of efficiency.” 

Over the past decade and a half, silicon PV efficiency has increased making it more viable. At this point, 20 percent efficiency will be the norm in term of silicon PV, Swanson said. That’s led to PV being installed on more homes, in utility-scale projects and across the world, but more work needs to be done to grow adoption of the technology. 

Soft costs are one of the biggest roadblocks to more adoption—at least in the U.S. “Average module prices are down by an average factor of two almost in the last year,” said David Danielson, DOE assistant secretary of Energy Efficiency and Renewable Energy. “We haven't seen nearly the same reduction in installation and soft costs.” The SunShot Initiative, he said, is focusing on the right policies to address the issue, he said. 

“What I'm particularly excited about is this emerging virtuous cycle that the industry and key areas in SunShot are all working together on,” Danielson said. If the efforts successfully tackle and drive down installation costs, soft costs and hard costs of solar in the U.S. it will drive installation volume in the U.S. The installation volume in the U.S. will add gravity to the case for PV manufacturing in the U.S., he said.

There’s still a lack of knowledge said Dan Arvizu, director of the National Renewable Energy Laboratory, where much of the work is focussed on reducing the costs of solar while increasing solar efficiency. It’s obvious to industry observers, he said. “When I go out and talk to people outside it’s not so obvious. That's the idea there needs to be a transformation of our energy system. Specifically what's missing in the debate…is this idea that this a very global long-term systems level portfolio management type of problem which has attendant solutions.”

There’s no one solution, according to Arvizu. “We should be looking at a variety of technology pathways,” he said. As different technologies increase, the portfolio of options needs to be reevaluated. “The portfolio should be rebalanced as technology improves and as the external environment changes and all the things that we cannot anticipate today come into our views.”

Even now that’s happening. “There are some really interesting ideas in terms of first generation technologies using science that we did not fully understand and appreciate before,” Arvizu said. NREL, for instance is now using inverse design in its Energy Research Frontier Center (EFRC) to discover new materials for solar. “It's kind of playing Jeopardy with the processes of materials,” he said. “As opposed to how we do it today, which is here's some compatible materials, let’s see what the properties are. And we're now reversing that so that we can actually tailor the materials in ways that we haven't been able to before. That's true both in the more conventional mainstream technologies as well as in some of the new technologies.”