The costs of solar and coal power in China could become comparable countrywide by 2023, a new US-China study has found, indicating that the country, the largest carbon emitter globally, could be at a tipping point towards transitioning to clean energy faster than expected.

In two years, China will have the capacity to install solar power across the country at the same price as coal, and currently has that ability to do so in three-quarters of the country, the joint study found. “About 78.6% (79.7 PWh or petawatt-hour) of China’s technical potential will realise price parity to coal-fired power in 2021, with price parity achieved nationwide by 2023.”

Solar energy could provide 43.2% of China’s electricity demands in 2060 at less than two-and-a-half US cents per kilowatt-hour, it found; for comparison, coal power tariffs in China ranged 3.6 to 6.5 cents per kilowatt-hour in 2019, researchers from Harvard, Tsinghua University in Beijing, Nankai University in Tianjin, and Renmin University of China in Beijing said in the study.

The research forecast that “…nationwide parity is estimated to be achieved by 2023. Solar power in the North China, Northeast, East China, and Tibet grids is projected to achieve full price parity with coal in 2021, followed by the Central China, Northwest, and South China grids in 2023”.

The research was published as the cover article of the Proceedings of the National Academy of Sciences (PNAS), a peer-reviewed science journal on Tuesday.

“Today, subsidy-free solar power has become cheaper than coal power in most parts of China, and this cost-competitive advantage will soon expand to the whole country due to technology advances and cost declines,” Xi Lu from the School of Environment, Tsinghua University and co-corresponding author of the paper, said in a statement published by Harvard’s School of Engineering and Applied Sciences.

The researchers, according to the Harvard statement, first found that the physical potential of solar PV, which includes how many solar panels can be installed and how much solar energy they can generate, in China reached 99.2 petawatt-hours in 2020.

It was “…more than twice the country’s total consumption of energy in all forms, including not only electricity but also fuels consumed directly by vehicles, factories, building heating and more. The findings show solar PV is an enormous resource for China’s decarbonisation”.

“They then demonstrated its cost-competitiveness, with 78.6% of the potential in 2020 equal to or lower than current prices of local coal-fired power, a share set to grow further. This cost advantage means China can invest in storage capacity, such as batteries, and still cost-effectively supply 7.2 petawatt-hours or 43.2% of country-wide electricity demand by 2060,” the statement said.

“Our results demonstrate that the economic competitiveness of solar power combined with investments in storage systems could provide extra benefits for grid dispatch, which will be especially important for operation of future electric systems in China,” Xi, the Tsinghua university professor, said.

China has the world’s largest solar power capacity, with 253 GW of installed capacity at the end-2020 compared with about 151 GW in the European Union, according to International Energy Agency data.

China is expected to add up to 65 GigaWatts (GW) of solar power capacity in 2021, taking total solar installations beyond 300 GW by the end of the year, the China Photovoltaic Industry Association (CPIA) said at a conference in July this year.

“Most now realise that climate change requires transitioning away from fossil energy use,” said Chris P Nielson, executive director of the Harvard-China Project and a co-author of the paper.

“Not as many realise that decarbonising the power system is the linchpin, especially as more sectors become electrified, and that accommodation by the grid of renewable variability is the toughest part of the puzzle. It’s a huge breakthrough, and not just for China, if storage can make solar power grid-compatible at a competitive cost,” Nielson said.

The report comes ahead of the global climate summit in Scotland beginning on October 31 as Beijing’s plans to change from coal-based energy will be a major factor in the world’s ability to limit climate change.

Last week, President Xi Jinping pledged to accelerate the development of solar power in China. “[We will] step up our efforts in the development of renewable energy, and accelerate the planning of large-scale photovoltaic and wind power projects in [our] deserts and nearby areas,” he said, adding that the phase one of these projects with a combined installed capacity of 100 million kilowatts will begin construction soon.

Xi has also pledged to peak carbon emission by 2030 and carbon neutrality by 2060.