A black solar collector, with a surface area of 60 m², is placed on the roof of a house. Incident solar energy reaches the collector with a flux of 800 W/m². The surroundings are considered black with an effective temperature of 30°C. The convective heat-transfer coefficient between the collector and the surrounding air, at 30°C, is 35 W/m · K. Neglecting any conductive loss from the collector, determine

a. The net radiant exchange between the collector and its surroundings

b. The equilibrium temperature of the collector