energy efficiency equation of the solar collector?

(3) Derive an energy efficiency equation of the solar collector by finding the mathematical relationship between the energy efficiency and the absorber temperature above the ambient temperature per unit solar radiation on the solar collector. (4 marks)

(4) Plot the energy performance curve on a 2D plane coordinate to represent the relationship between the energy efficiency of the solar collectors and the absorber temperature above the ambient temperature per unit solar radiation on the solar collectors. Please indicate the maximum energy efficiency of the solar collectors and the maximum absorber temperature above the ambient temperature per unit solar radiation on the chart. You can assume that the transmissivity of the vacuum tube is 0.9, the absorptivity of the absorber is 0.95 and the heat loss coefficient of the solar collector is 1.12 W/(m2 ˚C). (6 marks)