  If light hidden sector photons exist, they could be produced through kinetic
mixing with solar photons in the eV energy range. We propose to search for this
hypothetical hidden photon flux with the Super-Kamiokande and/or upgraded CAST
detectors. The proposed experiments are sensitive to mixing strengths as small
as 10^-9 for hidden photon masses in the sub eV region and, in the case of
non-observation, would improve limits recently obtained from photon
regeneration laser experiments in this mass region.
