In May 2022, solar energy experts from around the world gathered in Germany for the third Terawatt Workshop. Almost a year later, excerpts from discussions at the workshop—combined with an extensive review of carbon dioxide emissions studies, energy demand forecasts, and the state-of-the-art in solar PV technology—led to the conclusion that 75 TW of installed solar capacity. by 2050 was a realistic global goal. More than 50 leading experts in the solar industry recently outlined the opportunity and challenges for solar energy to achieve this goal.
Since the beginning of 2016, Terawatt Workshops – jointly organized by Germany’s Fraunhofer Institute for Solar Energy Systems (ISE), the US National Renewable Energy Laboratory (NREL) and Japan’s National Institute of Advanced Industrial Science and Technology – have invited creators from the PV sector and research communities around the world to discuss about the future of the industry and its role in the wider energy system.
The workshops were originally convened to discuss how solar electricity would reach 1 TW of installed capacity worldwide – a target reached in 2022. The group’s scope then expanded to explore the role of solar energy in future energy systems. It settled on a target estimate of global annual solar installations of 75 TW by 2050. The participants of the third workshop held last year understood that the sun is one of the limited options both to meet the energy needs of the future and to cut greenhouse gases. greenhouse gas emissions. The participants also agreed that goals and a clear picture of the role of solar energy are vital in leading the industry on a larger scale.
“The big global risk would be to make bad assumptions or mistakes in modeling and promoting the required solar deployment and industry growth, and then realize by 2035 that we were deeply wrong on the low side and need to increase production and deployment to an unrealistic or unsustainable level,” explains Nancy Haegel, Director of NREL’s National Photovoltaic Center.
Haegel and about 50 other industry leaders co-authored a paper that examines the challenges and requirements for PV to reach 75 TW. The paper “Photovoltaics at multi-terawatt scale: Waiting is not an option” was published in “Science”. The authors looked at other works on future energy systems and looked for those that best take into account growing trends such as intersectoral coupling and growing energy consumption in the global south.
“In most cases, the models are based on photovoltaics, which generate 60% of the world’s electricity, and the wider electrification of the transport and heating sectors,” said Fraunhofer ISE director Andreas Bett. “Solar energy is by no means the only source of energy in these scenarios, but it is central. And this requires a major expansion of the entire industry.”
Bett said the next 10 to 15 years will be critical as the solar industry enters its terawatt era and lays the foundation for an industry capable of supplying so much of the world’s energy.
“Of course there is uncertainty, but this figure of 75 TW is the result of extensive discussion and we believe it is realistic,” says Bett. “With this kind of assumption, we can really talk about what the growth rate of efficiency and production capacity is needed. That’s a very important message to the industry, and if we wait until we know exactly what the number is, it’s going to be even more challenging to achieve.”
While the paper outlines the need to significantly expand solar power in the coming years and conveys this message with some urgency, it also makes it clear that the goals are entirely achievable and that the industry is already on the right track. Over the past five to 10 years, solar PV installations and generation capacity have grown at around 25% per year, and if this rate can be maintained, the target of 75 TW can be reached by 2050. “Of course people say it’s going to be challenging,” Haegel says. “But many do not realize that solar energy has already grown at the required rate. So we tried to outline the next step: what’s new and challenging about it, but also why it’s completely accessible.
Materials and manufacturing
The paper notes the rapid adoption of new technology in solar power manufacturing as proof of its ability to overcome new challenges. Listed achievements include diamond wire sawing, hydrogenation for defect control, and the move to larger wafers. In particular, everything was implemented quickly and managed well in the supply chain.
“Since 2010, the PV industry has changed from a somewhat slow-moving and conservative industry focused on individual component costs … to a highly dynamic industry focused more on levelized electricity costs,” wrote the paper’s authors. The researchers find that the last TOPCon (tunnel oxide passivated contact) technology moved from the original industrially relevant laboratory design to mass production in just five years. “Recent analysis shows that it now takes about three years for the average mass-produced cell efficiency to reach the efficiency of a master cell made in an industrial laboratory,” the paper stated.
The researchers conclude that the use of silver in solar power is now the most important material sustainability issue, and the current consumption level of about 15 mg/W must be reduced by a factor of three or eliminated entirely. They advise that when new materials are introduced, similar situations with other scarce materials should be avoided. “Technologies that address the use of scarce materials should be approached from an eco-design point of view and analyzed with life-cycle assessment to confirm impacts and evaluate metrics such as resource depletion and greenhouse gas emissions,” states the “Science” paper.
The need for sustainability to be taken into account throughout the expansion of solar energy production is also a key consideration. “Research and development in ecological design and recycling must be stepped up now to support the rapid and sustainable scaling of solar power,” the authors wrote. “The solar industry must constantly innovate to improve the durability of materials and reduce the embedded carbon and energy required to manufacture and deploy solar power.”
Despite the challenges of the current level of silver consumption, the research has a positive message about future material consumption. The scope and efficiency required by the photovoltaic industry can be achieved with current resources.
“The important message to policy makers is that there are basically no limitations on the materials side, but the resources we need to reach 75 TW are available,” says Haegel. “It’s very important that we have no fear. The message here is that yes, we can do it.”
Batteries, other technology
Another message visible in the work is that solar is not alone, and related innovations are needed in many other industries to achieve the goal of a completely renewable energy system. Above all, this means comparable scaling in energy storage, green hydrogen/e-fuels and the wind power industry.
Several industries also have to update their practices. This includes increasing acceptance of building-integrated solar power; introduction of electrified heating and cooling in the construction sector; widespread adoption of electric vehicles—models that encourage charging during periods of high solar production—and closer connections to the agricultural industry through agroelectricity. All of these developments are cited as strategies that can help solar power stay on track to become the world’s primary energy source.
The paper concludes with the message that the next step is to focus on developing more globalized supply chains at all levels. This, along with other measures, will require the support of policy makers around the world to ensure that solar is the first choice for energy expansion and that electricity grids are able to make efficient use of solar-generated electricity.
The paper concluded: “Recent history and current trends suggest continued global PV growth of 25% per year over the next decade towards 75 TW of installed PV by 2050. Waiting is not an option.”
