6 Estimate the amount of solar energy input to a horizontal collector per year whose surface area is 4 m2 for locations (A and B) with the average daily solar radiation values on a horizontal surface of 13740 kJ/m2 and 16240 kJ/m2. Also determine the equivalent amount of natural gas that would provide the same amount of energy. Take the higher heating value of natural gas to be 35,000 kJ/m3