  The recent measurement of Delta_{sol} by the KamLAND experiment with very
small errors, makes definitive predictions for the energy dependence of the
solar neutrino survival probability P_{ee}. We fix Delta_{sol} to be the
KamLAND best fit value of 8*10^{-5} eV^2 and study the energy dependence of
P_{ee} for solar neutrinos in the framework of two flavour oscillations and
also of three flavour oscillations. For the case of two flavour oscillations,
P_{ee} has a measurable slope in the 5-8 MeV range but the solar spectrum
measurements in this range find P_{ee} to be flat. The predicted values of
P_{ee}, even for the best fit value of theta_{sol}, differ by 2 to 3 sigma from
the Super-K measured values in each of the three energy bins of the 5-8 MeV
range. If future measurements of solar neutrinos by Super-K and SNO find a flat
spectrum with reduced error bars (by a factor of 2), it will imply that two
flavour oscillations can no longer explain both KamLAND data and the solar
spectrum. However a flat solar neutrino spectrum and the Delta_{sol} measured
by KamLAND can be reconciled in a three flavour oscillation framework with a
moderate value of theta_{13} approx 13 degrees.
