Ascent Solar Technologies Inc. (NSDQ: ASTI) shares are down less than 4 percent after the company announced the resignation of its chief executive Monday.

Matthew Foster, the company's president and CEO until last Friday, and the board "have mutually decided that a change of leadership presents the best path forward for the company, as it heads into the manufacturing phase of its development," according to the announcement.

"Ascent Solar is transitioning from a research and development company to a manufacturing and commercially focused organization," Foster said in a written statement. "I felt that new leadership would be better at leading Ascent Solar's next phase of growth where operational and manufacturing expertise will be critical."

Foster will consult for the company regarding its business development, as well as its plans for global expansion, for a year, according to the company.

Ascent gave no further reason for Foster's resignation, and doesn't have a permanent replacement lined up. It said Mohan Misra, the company's chairman and chief strategy officer, will serve as the interim CEO in the meantime.

The company is developing thin-film solar technology that it claims can reduce the weight, cost and complexity of solar panels by coating plastic film with copper, indium, gallium and selenium (see a video simulation of its process here).

Ascent completed construction of a 1.5-megawatt line in December, and in March began production trials on the line, according to a quarterly report released in August. The company plans to reach 30 megawatts of capacity next year and 110 megawatts of capacity by the end of 2011.

It faces some efficiency challenges, however.

Before beginning production on the 1.5 megawatt line, the company had produced solar-cell prototypes that consistently were able to convert 10 percent to 12 percent of the sunlight that reached them into electricity, which resulted in solar panels with efficiencies of approximately 6 percent to 8 percent and as high as 9.6 percent, according to the filing.

Ongoing trials have produced cell efficiencies of 8 percent to 10 percent and panel efficiencies of 6 percent to 7.5 percent. The company in August said it would continue to systematically conduct production trials aimed at reaching consistent panel efficiencies of 7 percent to 8 percent before ramping up to full production on the 1.5-megawatt line.

The company didn't answer further questions about its ramp up or about Foster's resignation Monday.

Shares of Ascent fell 3.9 percent to close at $6.91 per share Monday.

Meanwhile, Medis Technologies Ltd. (NSDQ: MDTL) is up 17.65 percent to $2.80 per share after it announced it has appointed a new CEO and president.

Jose Mejia previously was the executive vice president of operations at Spansion Inc., a president of the supply chain and other areas at Lucent and a vice president of external manufacturing at Nortel Networks. He also worked at Owens Illinois, IBM and Ford Motor Co. and established a Hispanic community bank called Nuestro Banco.

Robert K. Lifton, the former CEO, will continue as the company's chairman, and Jacob Weiss, the former president, will become the executive vice president, the company said.

"This is a time of major change in our company's direction - the transition from a focus on development of the technology and a product line to an operating company introducing exciting products into the market, to be manufactured in large quantities with sources from a world wide supply chain," Lifton said in a written statement.

The company, which in 2005 said it would bring its portable fuel-cell-powered cell-phone charger to the market in 2006, has claimed to be on the cusp of commercialization for some time.

But the company expects it to happen for real this year. "While other portable fuel-cell solutions are only prototypes, the Medis 24-7 Power Pack will be widely commercialized later this year," according to its Website.

Others apparently believe it will happen too. In August, Medis said select Best Buy stores would offer its methanol fuel-cell charger beginning that same month. Its first high-volume assembly line, capable of producing up to 3 million chargers per month, was also expected to begin operating in the first half of this year in Ireland.

The company hasn't yet announced whether its products have reached Best Buy shelves on schedule.