**8.1 Solar energy thermal conversion application**


12 Solar Radiation

When they were tested on the year 2000 radiation data, the values predicted by eqn.12 were within 18% while that of eqn.13 was within 11% and that of eqn.14 was within 19%. Therefore it can be said of these equations that they will adequately produce diffuse sky radiation data with reasonable accuracy. Eqn.13 is however the best of the three. It is of the Angstrom type, obtained as a result of experimental analysis and not as a result of

Direct radiation component data is the most difficult to acquire because of the nature of the equipment for measuring it. Estimation of its values has therefore been relied upon to

The following formulas by the author for computing it were developed at various times

The two equations were developed in terms of the total radiation H and extraterrestrial radiation Ho. The two radiation fluxes, the predictors, are easily measured and computed respectively with very reasonable accuracy. Eqn.15, in particular, is a unique equation, developed purely from experimental results, Eqn.15 and eqn.16 will produce dependable

Some other equations developed for predicting Hb for specific atmospheric conditions are:

They have been tested and proven to be much more suitable for clear – sky conditions and cloudy – sky conditions respectively. They are equally as good as eqns. 15 and 16 above but

The major areas of application of solar energy are in the provision of low and high grade heat, direct conversion to electricity through Photovoltaic cells and indirect conversion to

values of the direct radiation data in all atmospheric conditions.

only at the atmospheric conditions specified.

**8. Solar energy applications** 

electricity through turbines.

where Hd/H is known as the cloudiness index.

Sh is the fraction of sunshine hours. Kc is the clearness index H/Ho.

regression analysis like others.

provide the data when needed.

(Babatunde, 1999; 2000)

and

**7.3 Direct radiation prediction formulas** 

**Hd/H = 0.945 – 0.971Kc** (13)

**Hd/H = 1 - Kc** (14)

**Hb = H2/Ho** (15)

**Hb/H = 0.308 + 0.424 H/Ho** (16)

**Hb/H = 0.341 + 0.571 Kc** (17)

**Hb/H = 0.247 + 0.415 Kc** (18)

