  The next-generation neutrino experiment JUNO will determine the solar
oscillation parameters - $\sin^2 \theta_{12}$ and $\Delta m^2_{21}$ - with
great accuracy, in addition to measuring $\sin^2\theta_{13}$, $\Delta
m^2_{31}$, and the mass ordering. In parallel, the continued study of solar
neutrinos at Hyper-Kamiokande will provide complementary measurements in the
solar sector. In this paper, we address the expected sensitivity to
non-universal and flavour-changing non-standard interactions (NSI) with
$d$-type quarks from the combination of these two future neutrino experiments.
We also show the robustness of their measurements of the solar parameters
$\sin^2 \theta_{12}$ and $\Delta m^2_{21}$ in the presence of NSI. We study the
impact of the exact experimental configuration of the Hyper-Kamiokande
detector, and conclude it is of little relevance in this scenario. Finally, we
find that the LMA-D solution is expected to be present if no additional input
from non-oscillation experiments is considered.
