  We compute cosmic ray (CR) nuclei, proton, antiproton, electron and positron
spectra below 1 TeV at Earth by means of a detailed transport description in
the galaxy and in the solar system. CR spectra below 10 GeV are strongly
modified by charge-sign dependent propagation effects. These depend on the
polarity of the solar magnetic field and therefore vary with the solar cycle.
The puzzling discrepancy between the low-energy positron fraction measured by
PAMELA and AMS-01 is then easily explained by their different data-taking
epochs. We reproduce the observed spectra of CR light nuclei within the same
galactic and solar-system propagation model.
