Chapter 6
PV Value Chain and Technology
6.1 Basics of Solar Radiation and Conversion in PV Cells
The solar spectrum outside the earth’s atmosphere has a power density of 1,300 W/m2; this is called the “solar constant”. The energy distribution for the photons (energy per wavelength and area) is shown in Fig 6-1 and resembles the radiation of a black body radiator with a temperature of 6,000 Kelvin – the temperature at the surface of our sun. The visible part of the spectrum from about 400 nm (ultraviolet) up to about 700 nm (red) is only a small part of the complete spectrum. The relationship between energy, frequency and wavelength for a photon is described by
with E the energy of the photon, h Planck’s constant, v the frequency, c the light velocity and λ the wavelength.
Entering the atmosphere, some absorption of light takes place due to water vapor and other molecules and aerosols in the air. The absorption bands at the various wavelengths of H2O (900, 1,100, 1,400, 1,900 and 2,500nm), O2 (750nm), O3 (250nm), and CO2 (2,050nm) are indicated and result in the decrease of the yellow area down to the red one. This decreases the power of the sunlight which is coming from the outside of the atmosphere. If ...
Get The Economic Competitiveness of Renewable Energy: Pathways to 100% Global Coverage now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.