Page 341 - Handbook of Energy Engineering Calculations

FIGURE 13 Average solar radiation, Btu/ft (× 3.155 = W/m ),
2
2
horizontal surface in the month of January. (DOE/CS-0011.)

3. Find the HA/L ratio for this installation
2
2
Use Fig. 14 to find the HA/L ratio, where A = collector area, ft (m ). Enter
Fig. 14 on the left at the fraction F of the annual load supplied by solar
energy; project to the right to the tinted area and then vertically downward to
the HA/L ratio. Thus, for F = 60 percent, HA/L = 1.0; F = 80 percent, HA/L =
1.5; for F = 90 percent, HA/L = 2.0.