The Sun fills almost none of the sky. Here is why it still matters.
A radiator in orbit looks out at a sky that is almost all 3 K. The Sun's disc covers about 0.001 % of what a flat face sees, so turning a face toward the Sun hardly blocks its view of cold space. The instinct that the Sun is a small thing in the sky is right.
It is wrong about the heat. The Sun's surface is at 5,772 K, and because thermal emission goes as T⁴, that tiny patch delivers 1,361 W per m²: about twice what a 60 °C radiator face sends out. How much of it the face keeps depends on its coating. White paint absorbs about a fifth; black paint absorbs nearly all of it.
A companion to watts-to-space, the full model, and to Your laptop in space. The full model keeps its radiators knife-edge to the Sun; this page lets you turn them toward it.
A flat panel radiating from both faces, held edge-on to Earth below. Sunlight strikes one face at the angle you set; 90° is knife-edge, the way space data centers fly their radiators.