This paper provides an insight into the specifications for electric double layer capacitor systems (EDLCs), design issues and production technology. It focuses on systems with power ratings far in excess of 100 kW and with short cycle times. As a result, a major topic of interest is EDLC cooling. Several cooling concepts are compared with each other based on experimental data. This is done for four EDLC configuration types. Mechanical aspects and diagnostics of the electric and thermal system are also covered.