Create a "Clear Sky Insolation Calculator" for direct, diffuse and reflected radiation using the spreadsheet shown below as a guide.
Confirm that it gives you 859 W/m2 under the following conditions: August 1, 30° latitude, tilt 40°, southwest facing (-45°), 3 pm solar time, reflectance 0.2.
Use the calculator to compute clear sky insolation under the following conditions (times are solar times):
b. January 1, latitude 40°, horizontal insolation, solar noon, reflectance = 0
c. March 15, latitude 20°, south-facing collector (azimuth 0°), tilt 20°, 11:00 am, reflectance =0.2
d. July 1, latitude 48°, south-east collector (azimuth 45°), tilt 20°, 2:00 pm, reflectance = 0.3