Page 316 - Handbook of Energy Engineering Calculations

FIGURE 3 Average amount of solar energy available, in Btu/(day ·
2
2
ft ) (W/m ), for different parts of the United States. (Power.)

When you make this estimate, keep in mind that on a clear, sunny day

direct radiation accounts for 90 percent of the insolation. On a hazy day only
diffuse radiation may be available for collection, and it may not be enough to
power the solar heating and cooling system. As a guide, the water

temperatures required for solar heating and cooling systems are:

2. Choose collector type for the system
There are two basic types of solar collectors: flat-plate and concentrating
types. At present the concentrating type of collector is not generally cost-

competitive with the flat-plate collector for normal space heating and cooling
applications. It will probably find its greatest use for high-temperature
heating of process liquids, space cooling, and generation of electricity. Since
process heating applications are not the subject of this calculation procedure,