COLLECTOR ENERGY BALANCE.

 The collector parameters described

above allow an energy balance to be expressed as:

Energy Collected = Solar Energy Absorbed - Thermal Energy Losses to the

Environment

The energy balance can be written in a simple equation form using the efficiency

parameters described above:

Energy Collected = (FRta)(I)(Ac) - (FRUL)(Ac)(Ti - Ta) (Eq. 1)

Equation 1 shows that heat losses to the environment are subtracted from the net solar

radiation transmitted into, and absorbed by, the collector. Assuming that the efficiency

parameters are fixed for a given collector model, the main factors that affect the amount

of energy collected are I, Ti, and Ta. The geographical location and the season dictate

the weather variables I and Ta. The type of process load and system configuration

determines the relative circulation fluid temperature, Ti.

Typical collector efficiency curve

Typical solar collector efficiency plots