  We calculate the solar neutrino and antineutrino flux in the keV energy
range. The dominant thermal source processes are photoproduction ($\gamma e\to
e \nu\bar\nu$), bremsstrahlung ($e+Ze\to Ze+e+\nu\bar\nu$), plasmon decay
($\gamma\to\nu\bar\nu$), and $\nu\bar\nu$ emission in free-bound and
bound-bound transitions of partially ionized elements heavier than hydrogen and
helium. These latter processes dominate in the energy range of a few keV and
thus carry information about the solar metallicity. To calculate their rate we
use libraries of monochromatic photon radiative opacities in analogy to a
previous calculation of solar axion emission. Our overall flux spectrum and
many details differ significantly from previous works. While this low-energy
flux is not measurable with present-day technology, it could become a
significant background for future direct searches for keV-mass sterile neutrino
dark matter.
