This reports how many modules in this DC group have genuinely failed, the DC-side equivalent of tsiACGroupNbModKO, useful for spotting whether failures cluster within modules sharing a specific battery string rather than being independently distributed across the site. A concentration of failures within one DC group, rather than spread evenly, points toward a problem with that specific string's DC feed quality, a failing battery, loose connection, or DC bus fault, rather than coincidental individual module defects. An admin seeing elevated failures isolated to one DC group would inspect that battery string's terminals and connections before assuming several modules independently failed by chance.