NOVELTY - Modular fuel cell system comprises a metal base (20); power modules (12) arranged in a row on the base; and a fuel processing module (16) and a power conditioning module (18) arranged on an end(s) of the row on the base. Each of the power modules comprises a separate cabinet comprising a fuel cell stack(s) located in a hot box; and the power modules are electrically and fluidly connected to the fuel processing module and the power conditioning modules through the base.    USE - Modular fuel cell system.    ADVANTAGE - The modular design of the fuel cell system enclosure provides flexible system installation and operation. Modules allow scaling of installed generating capacity, reliable generation of power, flexibility of fuel processing, and flexibility of power output voltages and frequencies with a single design set. The modular design results in an always on unit with very high availability and reliability, provides an easy means of scale up and meets specific requirements of customer's installations and allows the use of available fuels and required voltages and frequencies, which may vary by customer and/or by geographic region. Each of the modules may be electrically disconnected, removed from the fuel cell enclosure and/or serviced or repaired without stopping an operation of the other modules in the system, allowing the fuel cell system to continue to generate electricity. The entire fuel cell system does not have to be shut down if one stack of fuel cells in one hot box malfunctions or is taken off line for servicing. The system can be assembled with power modules in a mirrored configuration, simplifying assembly and maintenance.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method of assembling a modular fuel cell system.    DESCRIPTION OF DRAWING(S) - The drawing is an isometric view of modular fuel cell system.    Modular fuel cell system enclosure (10)    Power modules (12)    Fuel processing module (16)    Power conditioning module (18)    Metal base (20)