TNO is developing a carbon-contamination-insensitive EUV power sensor that uses the photo-electric effect to distinguish between in- and out-of-band EUV. An LPP EUV source also emits out-of-band (OoB) photons, generating secondary electrons (SE’s) with a different energy than the SE’s generated by in-band EUV photons (13.5 nm, 92 eV). Characterization of the SE yield and energy distribution from carbon is required for the optimization of the EUV power sensor selectivity to in-band EUV photons. To this end, we designed a Secondary Electron Energy Distribution (SEED) analyzer, to measure the SE yield and energy distribution. First, the SEED analyzer will be validated with an e-beam, then in the TNO EUV Beam Line. This research is funded by the Dutch TKI program HTSM in collaboration with ASML and Carl Zeiss.