Prices for glass that coats photovoltaic panels have risen 71 percent since July, and manufacturers are struggling to produce it fast enough to keep more than a week’s worth of sales in inventory, according to Daiwa Capital Markets. The shortage comes as the solar industry turns toward bifacial panels, which increase both power output and glass requirements.

Solar panel producers like Longi Green Energy Technology Co. have asked the government in China, home to most solar manufacturing, to address the situation by approving new factories. Otherwise price hikes risk making solar power too expensive and halting the industry’s momentum.

“If solar power generators see solar projects as uneconomical, they will delay investing in new projects and that will drag down solar demand,” said Charles Jiang, general manager of the supply chain management center at Longi, the world’s biggest solar company by market capitalization. “Solar power plant profits will drop below acceptable levels without government subsidies if glass makers go on to push up the costs.”

In 2018, with the energy intensive and polluting glass industry facing over-capacity issues, China’s government forbade companies from adding new production capacity. Longi and five other major solar companies on Tuesday met with government officials and appealed for them to remove the restrictions, at least for solar glass.

Bifacial Panels

Glass demand has also been rising within the solar industry because of the increasing prominence of bifacial panels, which coat both the top and bottom with glass, allowing for a slight uptick in power generation from sunlight reflected off the ground. Such panels are expected to make up half the market in 2022, up from about 14 percent last year, according to analysts at Sunwah Kingsway.

Solar glass manufacturers have soared this year, with Xinyi Solar Holdings Ltd. more than doubling and Flat Glass Group Co. nearly quadrupling in market value in Hong Kong. Shares plummeted Wednesday on speculation that capacity controls could be lifted and as a Democrat sweep in the US elections failed to materialize. They extended gains Friday along with other manufacturers as a win for Joe Biden and a greener agenda in the U.S. became more likely. Flat Glass gained 2.3 percent while Xinyi added 3 percent.

Flat Glass declined to comment. Xinyi didn’t respond to requests for comment, although company officials told Citigroup analysts the company could defend its market share with faster capacity expansion than others if restrictions are lifted.

For panel makers, glass now accounts for about 20 percent of the total cost of production, up from about 10 percent, Longi’s Jiang said. Because glass factories take so long to build, the solar industry could be 20 percent to 30 percent  short of the glass it needs next year, with the market not being back in balance until 2022, he said.

The shortage is coming at an inopportune time as solar developers are rushing to finish projects by the end of this year to secure government subsidies. It also threatens to halt momentum just as the Chinese government considers increasing renewable power additions as the country aims to rein in pollution and become carbon neutral by 2060.

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