In an industry as young as solar energy, all management transitions are big news and every departure is treated with seriousness.

With many of the companies working at times of inflection in the industry, key management personnel are central to leveraging still-emerging technology and balancing the short-term needs of investors and customers with the longer-term needs of government stakeholders.

One of the most-active solar developers in the business, First Solar, announced today that Jens Meyerhoff, president of the Utility Systems Business Group and former CFO, is leaving the company “to step back and reflect.” He will be replaced by James Brown, currently the Senior VP of Utility System Business Sales, while Frank DeRosa’s role as Senior VP of Business Devlopment for the Americas will be expanded. DeRosa will report to Brown, who will in turn report to First Solar CEO Rob Gillette.

The company rushed to reassure its investor as it announced the changes, promising it won’t lose momentum after a series of important deals in 2011.

“We are confident the transition will be seamless,” Gillette said in announcing the change. Meyerhoff discussed the company’s busy 2011 in saying he would leave the firm, including project milestones like the sale of the Agua Caliente project to NRG Energy and the construction start of the Desert Sunlight project.

Deals in recent months have included securing billions of dollars in loans guarantees from the Department of Energy for California solar projects, setting efficiency records for some panel types and signing new power purchase agreements with utilities. The company reported lower sales and profit for the first half of 2011, but confirmed expenditure of $800-900 million to support its growth plans.

The muted reaction of analysts to Meyerhoff’s departure could be another sign of the industry’s burgeoning maturity, covered in greater detail in Solar’s Sunniest Days Still Lie Ahead. Major banks covering the company maintained their buy rating on First Solar, with one infrastructure bank analyst calling the job change a “natural evolution” for the firm.