Photoluminescence (PL) is a fundamental light-matter interaction, which conventionally involves the absorption of energetic photon, thermalization and the emission of a red-shifted photon. Conversely, in optical-refrigeration the absorption of a low energy photon is followed by endothermic-PL of an energetic photon. Both aspects were mainly studied at relatively low temperatures, where thermal population is far weaker than the photonic excitation, obscuring the generalization of PL and thermal emissions. In contrast, at high temperatures the PL and thermal populations compete for dominance. Here, we experimentally study endothermic-PL at high temperatures. In accordance with theory, we show how PL photon rate is conserved with temperature increase, while each photon is blue shifted. Further rise in temperature leads to an abrupt transition to thermal emission where the photon rate increases sharply. We also show how endothermic-PL generates orders of magnitude more energetic photons than thermal emission at similar temperatures. Relying on these observations, we propose and theoretically study a thermally enhanced PL (TEPL) device for highly efficient solar-energy conversion, with thermodynamic efficiency limit of 70%.