Adam Duran is program manager at the National Renewable Energy Laboratory and co-director of the Shell GameChanger Accelerator powered by NREL.


The energy sector is making progress toward low- or zero-carbon generation. But even with recent technology developments and corporate and municipal action to deploy renewables, we still have a long way to go, and there is much debate about the best path forward.

Several researchers consider perovskite photovoltaics and long-duration storage necessary players in the energy transition. Here’s why.

PV can’t stand alone

Solar module manufacturing has achieved major milestones over the last 20 years, but today’s standard silicon solar panels can’t address our energy challenges alone. In order to meet Paris Agreement targets, solar must grow at an average of 15 percent each year until 2030. This rate of growth would require ongoing reductions in PV costs, even as solar reaches cost parity with coal and natural gas.

Researchers at the Department of Energy’s National Renewable Energy Laboratory (NREL) say perovskite solar cells, an emerging higher-efficiency thin-film alternative to silicon PV, can help. Perovskites are highly flexible and can conceivably be applied to curved and irregular surfaces. This creates opportunities to deploy solar directly on sources of energy consumption, such as covering the exterior of electric vehicles with solar paneling to extend a vehicle’s range.

Already perovskites are proving to be more efficient than standard silicon panels. Scientists studying and piloting combined perovskite-silicon cells, or tandem solar cells, recently broke performance records by converting 27 percent of sunlight to energy, a 7 to 12 percent increase in efficiency compared to silicon PV’s 15 to 20 percent.

Even with significant evolutions in performance, perovskites face roadblocks to get to market. An estimated 90 to 95 percent of startups fail due to a lack of proper financial and technical resources. “Hard” technology startups in particular fall prey to long development, testing and deployment times, and to complicate things further, perovskites face a heavily regulated environment, requiring them to navigate ever-changing restrictions and subsidies.

The biggest hurdle keeping perovskites from commercialization is cost. To address this, researchers are teaming up with innovators through the Shell GameChanger Accelerator powered by NREL (GCxN) to cut costs along the manufacturing process. One area of focus is a scalable, novel vapor-deposition manufacturing process.

With continued support from research and development agencies, the perovskite market is on pace to grow by more than 30 percent each year over the next decade.

Beyond a single energy storage solution

Photovoltaic technology isn't the only domain that researchers aim to diversify. Energy storage technology is expanding rapidly and will become increasingly important for balancing demand variability on the grid, particularly as the industry sees wider adoption of electric vehicles and distributed resources.

To date, lithium-ion batteries are responsible for expanding storage penetration through electric vehicles, residential deployments and other smaller-scale needs. But lithium-ion batteries are limited by an average four-hour duration capacity and pose life-cycle and sustainability challenges. They also require finite elements such as cobalt, nickel and graphite, all of which are procured through mining processes that have significant environmental and health consequences.

To diversify the sector, researchers and startups at GCxN are testing and piloting long-duration, organic flow batteries and hybrid solar-thermal PV systems. Organic compound-based redox flow batteries deliver a higher operating voltage and three to four times the energy density of traditional systems. Hybrid solar-thermal systems snap to the back of panels to cool the solar array — improving panel efficiency by as much as 25 percent — and stores would-be “waste heat” as energy to generate power-on-demand. Both technologies tackle the storage industry’s ongoing challenge: to store power cost-effectively and sustainably.

But just like perovskites, alternative storage technologies face the infamous “valley of death" and must reduce risk quickly in order to attract interest from prospective investors. Significant research capabilities to test technologies and reduce risk, as well as a robust network of experts to pilot projects and demonstrate scalability, are crucial components along a startup’s journey to market.

Expanding our arsenal of technologies for the energy transition

The bottom line is this: The energy industry will eventually max out how much it can lower costs and improve efficiencies of the existing resources we rely on today.

Yes, cleantech innovators face an uphill challenge first to get to market and then to successfully compete with incumbent technologies. But when they do, the impact is substantial. Perovskites, organic flow batteries and hybrid solar-thermal photovoltaic systems have the potential to function as entirely new markets, rife with investment opportunities and real-world impact.

Editor's note: The original story referred to cobalt, nickel and graphite as rare-Earth elements. While finite, they are not classified as rare-Earths.