"Be clear this is not an innovation," wrote Dong Kim just six weeks before the loan was approved. "The record will show we did not grade this as an innovation."
Kim also wrote, "someone keeps changing" internal memos to label project as meeting the innovative requirements.
Department of Energy officials, however, have noted that Kim ultimately signed off on the project as innovative, as did senior loan officers who conducted their own review.
Energy Department spokesman Damien LaVera told ABC News he believed the GOP had "cherry-picked" thousands of emails to invent a misleading controversy.
Chu told the committee that although the single axis tracker was not an entirely new technology, its use by First Solar was much larger in scale than any previous application and had been modified to boost efficiency.
"The question was, can you get a large project and the additional capital expense of tracking to make it work with at that time relatively low-efficiency panels, which were lower-cost to make," said Chu.
Today's hearing came as major private investors including Google and Warren Buffett are pushing into the solar industry. Bloomberg reports solar developers are promising investment returns of 15 percent, four times the rate of Treasury securities.