  We present a new solar radio imaging system implemented through the upgrade
of the large single-dish telescopes of the Italian National Institute for
Astrophysics (INAF), not originally conceived for solar observations.
  During the development and early science phase of the project (2018-2020), we
obtained about 170 maps of the entire solar disk in the 18-26 GHz band, filling
the observational gap in the field of solar imaging at these frequencies. These
solar images have typical resolutions in the 0.7-2 arcmin range and a
brightness temperature sensitivity <10 K. Accurate calibration adopting the
Supernova Remnant Cas A as a flux reference, provided typical errors <3% for
the estimation of the quiet-Sun level components and for active regions flux
measurements.
  As a first early science result of the project, we present a catalog of radio
continuum solar imaging observations with Medicina 32-m and SRT 64-m radio
telescopes including the multi-wavelength identification of active regions,
their brightness and spectral characterization. The interpretation of the
observed emission as thermal bremsstrahlung components combined with
gyro-magnetic variable emission pave the way to the use of our system for
long-term monitoring of the Sun. We also discuss useful outcomes both for solar
physics (e.g. study of the chromospheric network dynamics) and space weather
applications (e.g. flare precursors studies).
