Page 342 - Handbook of Energy Engineering Calculations

FIGURE 14 Fraction of annual load supplied by a solar hot-water
heating system as a function of January conditions. (DOE/CS-0011.)

4. Compute the solar collector area required

Use the relation HA/L = 1 for the 60 percent fraction. Or, HA/L = 1, A = L/H
2
2
= 0.6(90,072)/580 = 93.18 ft (8.7 m ). For HA/L = 1.5 for the 80 percent
2
2
fraction, A = 0.8(90,072)/580 = 124.24 ft (11.5 m ). And for the 90 percent
2
2
fraction, A = 0.9(90,072)/580 = 139.77 ft (12.98 m ).
Comparing these areas shows that the 80 percent factor area is 33 percent
larger than the 60 percent factor area, while the 90 percent factor area is 50
percent larger. To evaluate the impact of the increased area, the added cost of
the larger collector must be compared with the fuel that will be saved by
reducing the heat input needed for DHW heating.

Related Calculations. Figures 13 and 14 are based on computer calculations
for 11 different locations for the month of January in the United States

ranging from Boulder, CO, to Boston; New York; Manhattan, KS;