Future solar neutrino experiments and neutrino spin-flavour precession

The main features of the observables in the SNO and Super-Kamiokande solar neutrino experiments in the case of neutrino spin and/or spin-flavour precession in the magnetic field of the sun are discussed. It is shown without any model dependent assumption that in the case of Majorana transition magnetic moments the NC event rate $N^{\mathrm{NC}}$ does not depend on time and a measurement of $N^{\mathrm{NC}}$ will allow to determine the initial flux of $^8\mathrm{B}$ neutrinos with a theoretical uncertainty of a few \%. In the case of Dirac magnetic moments the NC event rate will depend on time and we obtain a model independent lower bound for the transition probability of initial $\nu_e$'s into right-handed sterile neutrinos