  The Jiangmen Underground Neutrino Observatory (JUNO), the first multi-kton
liquid scintillator detector, which is under construction in China, will have a
unique potential to perform a real-time measurement of solar neutrinos well
below the few MeV threshold typical for Water Cherenkov detectors. JUNO's large
target mass and excellent energy resolution are prerequisites for reaching
unprecedented levels of precision. In this paper, we provide estimation of the
JUNO sensitivity to 7Be, pep, and CNO solar neutrinos that can be obtained via
a spectral analysis above the 0.45 MeV threshold. This study is performed
assuming different scenarios of the liquid scintillator radiopurity, ranging
from the most opti mistic one corresponding to the radiopurity levels obtained
by the Borexino experiment, up to the minimum requirements needed to perform
the neutrino mass ordering determination with reactor antineutrinos - the main
goal of JUNO. Our study shows that in most scenarios, JUNO will be able to
improve the current best measurements on 7Be, pep, and CNO solar neutrino
fluxes. We also perform a study on the JUNO capability to detect periodical
time variations in the solar neutrino flux, such as the day-night modulation
induced by neutrino flavor regeneration in Earth, and the modulations induced
by temperature changes driven by helioseismic waves.
