This document discusses principles of solar radiation. It covers the role of solar energy, environmental impacts, physics of the sun, and measurements of solar radiation. Specifically, it defines the solar constant as the rate at which solar energy arrives at the top of the atmosphere, which is approximately 1.367 kW/m2. It also provides equivalent units of the solar constant in kcal/m2/hr and Btu/ft2/hr.

1. 1. Role and potential of new and renewable source.
2. The solar energy option.
3. Environmental impact of solar power.
4. Physics of the sun.
5. The solar constant.
6. Extraterrestrial and terrestrial solar radiation.
7. Solar radiation on titled surface.
8. Instruments for measuring solar radiation and sun shine.
9. Solar radiation data.
UNIT I PRINCIPLES OF SOLAR RADIATION
M.KARTHIKEYAN AP/MECH AAACET
SIVAKASI

2. M.KARTHIKEYAN AP/MECH AAACET
SIVAKASI
THE SOLAR CONSTANT

3.  The rate at which solar energy arrives at the top of the atmosphere
is called the solar constant.
[or]
 Solar constant is the amount of energy received in unit time on a
unit area perpendicular to the sun’s direction at the mean distance
of the earth from the sun.
M.KARTHIKEYAN AP/MECH AAACET
SIVAKASI

4. Solar constant ISC = 1.367 KW/m2
1165 Kcal/m2/per hour
432 Btu per sq.ft per hour
M.KARTHIKEYAN AP/MECH AAACET
SIVAKASI