  Sensitive radio instruments are optimized for observing faint astronomical
sources, and usually need to attenuate the received signal when observing the
Sun. There are only a handful of flux density calibrators which can comfortably
be observed with the same attenuation setup as the Sun. Additionally, for wide
field-of-view (FoV) instruments like the Murchison Widefield Array (MWA)
calibrator observations are generally done when the Sun is below the horizon to
avoid the contamination from solar emissions. These considerations imply that
the usual radio interferometric approach to flux density calibration is not
applicable for solar imaging. A novel technique, relying on a good sky model
and detailed characterization of the MWA hardware, was developed for solar flux
density calibration for MWA. Though successful, this technique is not general
enough to be extended to the data from the extended configuration of the MWA
Phase II. Here, we present a robust flux density calibration method for solar
observations with MWA independent of the array configuration. We use different
approaches -- the serendipitous presence of strong sources; detection of
numerous background sources using high dynamic range images in the FoV along
with the Sun and observations of strong flux density calibrators with and
without the additional attenuation used for solar observations; to obtain the
flux scaling parameters required for the flux density calibration. Using the
present method, we have achieved an absolute flux density uncertainty
$\sim10\%$ for solar observations even in the absence of dedicated calibrator
observations.
