  Most neutrino mass extensions of the standard electroweak model entail
non-standard interactions which, in the low energy limit, can be parametrized
in term of effective four-fermion operators $\nu_\alpha \nu_\beta \bar f f $.
Typically of sub-weak strength, $\epsilon_{\alpha \beta} G_F$, these are
characterized by dimensionless coupling parameters, $\epsilon_{\alpha \beta}$,
which may be relatively sizeable in a wide class of schemes. Here we focus on
non-universal (NU) flavor conserving couplings ($\alpha = \beta$) with
electrons ($f = e$) and analyse their impact on the phenomenology of solar
neutrinos. We consistently take into account their effect both at the level of
propagation where they modify the standard MSW behavior, and at the level of
detection, where they affect the cross section of neutrino elastic scattering
on electrons. We find limits which are comparable to other existing
model-independent constraints.
