A quantitative analysis of total radiation heat loss from a cavity receiver is numerically studied. Gaussian eliminations method is used to solve the setof radiosity equations to estimate total radiation heat losses from entire cavity surface. The radiation heat loss increases with increase in cavity wall temperature, aspect ratio, and emissivity. For the aspect ratios (L/d) in the range of 2–3, the view factor of all cavity surfaces is lower and most suitable for design. The mean radiation heat loss model always overestimates the radiation heat loss and the overall effect of temperature, aspect ratio, and emissivity may estimate mean radiation heat loss even 14% higher as compared to total loss from entire cavity. The mean radiation model is not appropriate to design a large size, high temperature cavity with low emissivity cavity material.