484 Photovoltaic Systems
superscript C refers to the solar cell. Therefore, as shown in Figure 9.11, the
applied voltage at the modules terminals is denoted by VM, whereas the total
generated current is denoted by IM.
A model of the PV module can be obtai
532 Solar Thermal Power Systems
Parabolic trough plants require a considerable amount of land that cannot be used concurrently for other purposes.
l Emissions occur when plants are operated with conventional fuels during hybrid operation.
As shown in Figure 9.6, the model contains a current source, Iph, one diode,
and a series resistance RS, which represents the resistance inside each cell. The
diode has also an internal shunt resistance, as shown in Figure 9.6. The net
Design of PV Systems 497
A remote cottage has the loads listed in Table 9.2. Find the average load and
peak power to be satisfied by a 12V PV system with an inverter.
Table 9.2 Loads for Cottage in Example 9.5
304 Solar Water Heating Systems
5.7 Solar water heater performance
Many test procedures have been proposed by various organizations to determine
the thermal performance of solar water heaters. Testing of the complete system
may serve a number o
522 Solar Thermal Power Systems
Figure 10.1 Schematic diagram of a solar-thermal energy conversion system.
The use of solar ponds for power production
Figure 9.2 Schematic diagrams of n- and p-type semiconductors. (a) n-type, with
excess electrons. (b) p-type, with excess positive holes.
Figure 9.3 Schematic diagram of a
Direct Collection Systems 435
Single-sloped cover design
Inflated plastic cover design
V-shape plastic cover design
Inclined glass cover design
Figure 8.2 Common designs of solar stills.
used, then that type of sol
Industrial Process Heat-General Design Considerations 393
The usual types of industries that use most of the energy are the food industry
and the manufacture of non-metallic mineral products. Particular types of food
industries that can employ solar proce
514 Photovoltaic Systems
Figure 9.23 Details of a water PV/T collector.
Indirect Collection Systems 447
a thin film over the horizontally arranged tube bundle in each effect. In the top
(hottest) effect, steam from a steam boiler or a solar collector system condenses
inside the tubes. Because of the low pressure created in th
Solar Angles 59
What are the maximum and minimum noon altitude angles for a location at
The maximum angle is at summer solstice, where is maximum, i.e., 23.5.
Therefore, the maximum noon altitude angle is 904023.573.5.
500 Photovoltaic Systems
Table 9.5 Values of bi Constants for Various PV Panels Tested at NIST
Silicon thin film
Parabolic Trough Collector Systems 529
If the dark saturation current of a solar cell is 1.7108A/m2, the cell temperature is 27C, and the short-circuit current density is 250A/m2, calculate the
open circuit voltage, Voc; voltage at maximum power, Vmax; current de
488 Photovoltaic Systems
9.3 Related equipment
Photovoltaic modules can be mounted on the ground or a building roof or can
be included as part of the building structure, usually the faade. Wind and snow
loading are major design considerations. The PV modu
Dish Systems 537
Figure 10.7 Heliostat detail of the Solar Two plant (source: www.energylan.sandia.
10.4 Dish systems
As was seen in Chapter 3, Section 3.2.3, dish systems use dish-shaped parabolic
mirrors as reflectors to concen
Solar Steam Generation Systems 399
Heat transfer fluid
Figure 7.7 The unfired boiler steam generation concept.
The major disadvantage of the system results from the characteristics of
the heat transfer flui
Heat Storage Systems 281
An energy balance of the storage tank gives
( Mc p )s
Qu Ql Qtl
Qurate of collected solar energy delivered to the storage tank (W).
Ql rate of energy removed from storage tank to load (W).
Qtlrate of energ
Passive Systems 253
Figure 5.1 Schematic diagram of a thermosiphon solar water heater.
replaced by the cooler water that has sunk to the bottom of the tank, f
468 Solar Desalination Systems
Tiwari, G.N., 2002. Solar Energy. Narosa Publishing House, New Delhi, India.
Tiwari, G.N., Noor, M.A., 1996. Characterization of solar still. Int. J. Sol. Energy 18, 147.
Tiwari, G.N., Singh, H.N., Tripathi, R., 2003. Presen
196 Solar Energy Collectors
Finally, the geometric factor is the ratio of the lost area to the aperture area.
The most complex parameter involved in determining the optical efficiency
of a parabolic trough collector is the
Direct Collection Systems 437
The partial vapor pressures at the water and glass temperatures can be
obtained from Eq. (5.21). The convective heat transfer coefficient can be obtained
= C (Gr Pr )n
d average spacing betw
Indirect Collection Systems 443
c mean specific heat under constant pressure for all liquid streams (kJ/kg-K).
Ntotal number of stages or effects.
The flashing temperature range, F, according to the temperatures shown
in Figure 8.5, is given by
F = Th - T
Desalination Processes 431
Mixing is an irreversible process; hence, the entropy of a mixture at a specified temperature and pressure is greater than the sum of the entropies of the
individual components at the same temperature and pressure before mixing.
Indirect Collection Systems 445
effect, which is at a lower pressure and receives its feed from the brine of the first
effect. This process is repeated all the way through (down) the plant. The distillate also passes down the plant. Both the brine and dis
Solar Radiation 97
2.3.8 Total Radiation on Tilted Surfaces
Usually, collectors are not installed horizontally but at an angle to increase
the amount of radiation intercepted and reduce reflection and cosine losses.
Therefore, system designers need data a
Power Tower Systems 535
By using thermal storage, power tower plants can potentially operate for 65%
of the year with no need for a backup fuel source. Without energy storage, solar
technologies such as the parabolic trough plants are limited to annual ca