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They are scrapping their production partnership after years of struggling to ramp up output at the Gigafactory 2 in upstate New York, according to the Nikkei Asian Review.
The companies will continue to work together on automotive batteries for Tesla's electric vehicles.
CEO Elon Musk remains enthusiastic about the business and its synergies with electric cars.
The solar cell agreement was announced in 2016.
Panasonic paid for the equipment at the gigafactory and started producing solar cells a year later.
The solar cells were to be used in Tesla's Solar Roof panels which look like roofing shingles.
The Panasonic-made cells reportedly failed to achieve the necessary look and performance.
The latest version of Solar Roof uses Chinese cells.
Tesla may soon need to find another use for that gigafactory.
Tesla's energy business was responsible for $1.53 billion, or just 6 percent, of overall revenue in 2019.
Tesla did not respond to Nikkei's request for comment.