Problem: A flat plate solar collector of area of 2 m2 is placed horizontally on the roof of a house. The collector surface has a temperature of 50oC and an emissivity of 0.1. We can assume that the collector takes up 75% of the thermo-solar radiation from the sun. The surrounding air has a temperature of 25 oC and flows with a velocity of 1/2 m/s so that a convective heat transfer coefficient of 5 W/(m2K) can be assumed along the solar collector. What is the area-specific thermos-solar radiation from the sun at this location?