  As a representative device exploiting both the solar energy and the radiative
cooling of deep-sky, the radiative temperature regulator (RTR) could switch
between heating and cooling modes self-adaptively at different temperatures.
However, the concept of RTR is challenging to be implemented due to the intense
parasitic absorption in phase-changing layers. Here, based on the theoretical
framework of energy conservation, we quantitatively reveal the intrinsic
relationships between solar heating and radiative cooling, especially
addressing the fundamental limiting factors, including the parasitic absorption
and the spectral emission selectivity, as well as the dynamic responses of the
phase-changing device under various operating conditions. The investigation
presents more insight into the underlying physics of RTRs and provides feasible
architectures for realizing such a kind of new functional device.
