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Recent filings by a customer of bankrupt solar panel manufacturer Abound Solar allege the company knew its panels were defective before the company collapsed last year, according to documents made public in the U.S. Bankruptcy Court in Delaware:

Citing confidential documents, Green Choice Solar LLC says the Colorado-based Abound knew about two major problems with some of the company’s solar panels.

The company’s disclosure, made public in a recent filing in U.S. Bankruptcy Court in Delaware, raises new questions about Abound Solar’s products and who will pay to get rid of solar panels that don’t work anymore. It’s unclear from the filing whether federal officials were told about defects. A spokesman for the Department of Energy, which awarded a loan to Abound Solar, declined to comment on the court filing when reached Wednesday.

Abound, a recipient of a $400 million loan guarantee from the Department of Energy, has faced scrutiny by local authorities in Colorado as well as a congressional probe seeking to uncover whether the company knowingly sold defective panels that in some cases suffered “catastrophic failure.”

As a result, both Abound and other companies have been left with thousands of “unsellable” solar panels facing hazardous waste disposal, should a buyer not emerge to reclaim or recycle the modules:

Meanwhile, Green Choice says it is stuck with thousands of Abound solar panels that are expensive to dispose of because they contain cadmium telluride, a toxic substance.

The company wants permission to file a request for court injunction seeking, among other things, assurances that funds will be available for the “safe and environmentally responsible” disposal of defective Abound panels that are now held by Green Choice.

According to Green Choice, Abound Solar acknowledged the existence of the defective panels in the company’s older modules, but the solar manufacturer went bankrupt before replacement could occur.

First Solar, another solar module maker who uses a similar cadmium telluride thin film technology, has emerged as a possible buyer and recycler of Abound’s defective, underperforming, and unsellable panels. The number of panels estimated to remain on Abound’s warehouse shelves numbers close to 100,000:

Joe Schieffelin at the CDPHE [Colorado Department of Public Health and Environment] said that minor amounts “100s of gallons” of hazardous chemicals had been left in the factory and had now been disposed of. But there were around 100,000 panels, many of which had been returned from customers who reported underperformance.

“Abound was having trouble with the quality control on their panels and some of them worked OK, some of them didn’t work at all, some of them worked partially. So many of them were returned and they accumulated a lot of panels that have a questionable quality.”

First Solar has offered to step forward “to support Abound for the sake of the industry.” Recycling and disposal is estimated to have a $2.2 million price tag.

If that deal falls through, the remaining panels would be buried in eastern Colorado:

If a buyer cannot be found, encasement in concrete would be a last resort, [Schieffelin] said.

When you talk about an inorganic product like a solar panel the only way to render those things safe to be disposed of in the ground is some kind of encapsulation—whether they would put that in cement or grind it up into little pieces and mix it into cement dust.”