Does it affect credibility/scoring of our application if this is the first time we are applying for the grant?

No, the credibility of first-time applicants is not affected by this; we have many new grantees each fiscal year. Please be sure to state you have never received a prior EN grant in the Past Performance section of your Project Narrative (Section 8). Please note, however, that there is an unfortunate aspect of the past performance evaluation criterion in which applicants with no past performance (no prior EN grants) receive half the past performance score as part of a ‘neutral’ score (per EPA grant policy).