(ShareCast News) - Proton Power Systems has signed a major reseller deal with German state-backed rail giant Deutsche Bahn (DB).DB's service company DB Bahnbau has agreed to sell and install Proton's containerised fuel cell systems as uninterruptible power supply (UPS) applications to parts of the DB group and external third party customers.The German railway giant, which is the largest railway operator and infrastructure owner in Europe and calls itself the second-largest transport company in the world, is planning to replace its installed base of diesel generator UPS systems with zero emission fuel cell applications over the coming years.Hailing the deal as a "key milestone" for the company, Proton chief executive Faiz Francoise Nahab said: "The decision of DB to use fuel cell UPS systems to replace old diesel applications is also to be seen as a milestone for our industry."Bahnbau will provide the site planning, installation and service for containerised systems from Proton, which recently expanded its manufacturing facilities to enable large quantity manufacturing capacity.In addition to DB, Bahnbau will also offer the same services to other potential customers in industries such as IT, transport and manufacturing.Proton said DB had chosen fuel cells for its UPS applications for their lower maintenance costs as well as environmental considerations.Shares in Proton were up 13.79% to 8.25p by 10:35 on Monday, hovering around their 12-month high.