1. Copyright © 2011 by Oxford University Press, Inc. Energy and the Environment James A. Fay / Dan S. Golomb FIGURE 8.5 The spectral distribution of the solar irradiance as a function of wavelength. The dotted line is the extraterrestrial irradiance and the solid line is the clear-sky ground-level irradiance for an overhead sun.

2. Copyright © 2011 by Oxford University Press, Inc. Energy and the Environment James A. Fay / Dan S. Golomb FIGURE 8.6 The ratio of daily diffuse to total radiation as a function of the ratio of daily total to extraterrestrial radiation, showing that cloudiness increases the diffuse portion of total radiation.

3. Copyright © 2011 by Oxford University Press, Inc. Energy and the Environment James A. Fay / Dan S. Golomb FIGURE 8.7 Annual average solar irradiance on a fixed flat plate collector (south facing, tilt angle = latitude) as a function of location in the contiguous United States. The gray scale shading covers the range of 170  270 W/m 2, northeast to southwest.

4. Copyright © 2011 by Oxford University Press, Inc. Energy and the Environment James A. Fay / Dan S. Golomb FIGURE 8.8 A flat plate collector absorbs incident sunlight on a thermally conducting collector plate that is cooled by a flow of liquid delivering the absorbed heat to a storage tank. A glass cover plate reduces the heat loss to the ambient environment.

5. Copyright © 2011 by Oxford University Press, Inc. Energy and the Environment James A. Fay / Dan S. Golomb FIGURE 8.9 The characteristics of solar heat collection systems as a function of collector area: (a) annual heat collection and (b) capital cost.

6. Copyright © 2011 by Oxford University Press, Inc. Energy and the Environment James A. Fay / Dan S. Golomb FIGURE 8.10 A focusing mirror (D m ) concentrates the solar irradiance I (dashed lines) on a smaller collector (D i ) located at the focal point of the mirror.