Stephen Battersby

PNAS January 2, 2019 116 (1) 7-10; https://doi.org/10.1073/pnas.1820406116

If the latest photovoltaic technologies can team up, they promise to capture the sun’s energy far more effectively than ever before.

In principle, the deluge of energy pouring down on us from the sun could meet the world’s power needs many times over. Already, in the United States, the total power capacity of installed solar photovoltaic (PV) panels is around 60 gigawatts, an amount expected to double in the next 5 years, and China increased its PV capacity by nearly 60 gigawatts in 2017 alone (1). Meanwhile, improvements in PV panel technology have driven down the price of solar electricity, making it cost competitive with other power sources in many parts of the world.

That’s not a bad start. But to take full advantage of that energy deluge and make a real impact on global carbon emissions, solar PV needs to move into terawatt territory—and conventional panels might struggle to get us there. Most PV panels rely on cells made from semiconducting silicon crystals, which typically convert about 15 to 19% of the energy in sunlight into electricity (2). That efficiency is the result of decades of research and development. Further improvements are increasingly hard to come by.

Material shortages, as well as the size and speed of the requisite investment, could also stymie efforts to scale up production of existing technologies (3). “If we are serious about the Paris climate agreement, and we want to have 30% [of the world’s electricity supplied by] solar PV in 20 years, then we would need to grow the capacity of silicon manufacturing by a factor of 50 to build all those panels,” says Albert Polman, leader of the photonic materials group at the AMOLF research institute in Amsterdam. “It may happen, but in parallel we should think about ways to make solar cells that take less capital.”

A slew of new technologies is aiming to tackle the terawatt challenge. Some could be cheaply mass produced, perhaps printed, or even painted onto surfaces. Others might be virtually invisible, integrated neatly into walls or windows. And a combination of new materials and optical wizardry could give us remarkably efficient sun-traps. In different ways, all of these technologies promise to harvest much more solar energy, giving us a better chance of transforming the world’s energy supply in the next 2 decades.

See more: https://www.pnas.org/content/116/1/7

Figure: Silicon solar panels have become cheaper and more efficient, but a slew of exotic materials and optical tricks promises to increase solar power’s potential far more in the coming years. Image credit: Shutterstock/Smallcreative.