Environmental Engineering Reference
In-Depth Information
Chapter 1
Photovoltaic Solar Energy Conversion
1.1 Introduction
Sunlight consists of electromagnetic radiation in the regions of
ultraviolet (UV), visible light, and infrared (IR) radiation. The
solar spectrum reaching the earth's surface undergoes various
absorptions in the air atmosphere, and the average solar energy
falling on the earth's surface is generally known as air-mass 1.5
(AM1.5) irradiation, which is equal to approximately 100 mWcm
−
2
.
This quantity is equal to
∼
1.0 kW of power falling on every square
metre, which humankind has not yet effectively utilised. The shape
of the solar spectrum and the absorption of various wavelengths
under AM1.5 conditions are shown in Fig. 1.1. Traditionally, there
are two ways of capturing solar energy. One method is to absorb
mainlytheheatenergy(orIRradiation),andthisisgenerallyknown
as 'solar thermal technology'. The second method is to convert
UV and visible light (photons) directly into electricity (measured
in volts). Since the photons are directly converted into volts, this
method is known as 'photovoltaic conversion' (PV conversion for
short). This topic concentrates only on the second method, which
is PV conversion.
