A former energy executive in California who took part in $1 billion solar power fraud that bilked Warren Buffett's company and many others was sentenced Tuesday to six years in federal prison and ordered to pay $624 million in restitution.

Robert A. Karmann, 55, of Clayton was the chief financial officer for DC Solar, a company based in Benicia in the San Francisco Bay Area that sold mobile solar generator units mounted on trailers.

The company marketed the generators between 2011 and 2018 as being able to provide emergency power for cellphone companies or to provide lighting at sporting and other events.

But the company executives started telling investors they could benefit from federal tax credits by buying the generators and leasing them back to DC Solar, which would then provide them to other companies for their use, prosecutors said.

The generators never provided much income, and prosecutors say the company ran a Ponzi scheme, in which early investors were paid with funds from later investors.

The company eventually stopped building the mobile generators altogether, and prosecutors say a least half the company's claimed 17,000 generators didn't really exist.

Among those suckered by the business were Buffett's Berkshire Hathaway Inc.
DC Solar founder Jeff Carpoff was sentenced last November to 30 years in prison and ordered to pay $790.6 million in restitution for conspiracy to commit wire fraud and money laundering.

His wife, Paulette Carpoff, 47, has pleaded guilty to federal charges and will be sentenced in May.

Prosecutors said the Carpoffs used the money to buy and invest in 32 properties, more than 150 luxury cars, a subscription to a private jet service, a semipro baseball team, a NASCAR race car sponsorship and a suite at the new Las Vegas Raiders stadium.

One other man was sentenced to three years in prison last year and three others pleaded guilty to criminal charges and await sentencing. (AP: Excluding headline)

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