U.S. solar startup Abound Solar said its chief executive will step down from that post for family reasons and become chairman.

Craig Witsoe will succeed Tom Tiller as president and CEO effective November 1, Abound said in a statement on Monday.

We have had some unexpected issues in our family, so I need to transition to a role with less day-to-day involvement, Tiller said.

Witsoe previously served as CEO of Lineage Power for three years. That company was sold to General Electric and is now known as GE Power Electronics.

Abound was founded in 2007 and is a competitor to First Solar Inc, the world's most valuable solar company. Both companies make solar panels using cadmium telluride, a less-expensive alternative to the polysilicon used to make traditional panels.

Abound received a $400 million loan guarantee from the U.S. Department of Energy in 2010 to build manufacturing plants in Longmont, Colorado, and Tipton, Indiana.