There are different types of fuel cell electric buses:

Standard buses (12 or 13 meter)

1) buses with a small battery and a large fuel cell ( for instance 120 kW) 

2) buses with a supercapacitor (instead of a battery) and a fuel cell (for instance 75kW)

3) buses with a large battery and a fuel cell as range extender

Articulated buses (18 meter buses)

4) buses with a larger battery and a fuel cell as range extender

Solaris : deployed in Hamburg

Van Hool bus - 13 m: deployed in Antwerpen, Aberdeen, Antwerp, Olso and Cologne

Evobus (Daimler) - 12 m: deployed in Aargau, Bozen, Milan, Stuttgart, Karlsruhe