Page 257 - Alternative Energy Systems in Building Design

CONCENTRATOR SOLAR TECHNOLOGIES 233

■ Buy only from a licensed contractor, and check on his or her experience and reputation.
■ Be aware that several factors should be considered when evaluating various system
configurations. More solar panels generally means your pool will be warmer.
■ Use a pool cover, if possible.
■ Make sure that the system is sized properly. An inadequately sized system is guar-
anteed dissatisfaction.
■ Beware of outrageous claims, such as “90°F pool temperatures in December with
no backup heater.” No solar heating system can achieve such performance.
■ The contractor should produce evidence of adequate worker’s compensation and
liability insurance.
■ Insurance certificates should be directly from the insurance company and not the
contractor.
■ Check the contractor’s referrals before buying.
■ Get a written description of the system, including the number of solar panels, the
size of panels, and the make and model numbers.
■ Get a complete operation and maintenance manual and startup demonstration.
■ The price should not be the most important factor, but it also should not be
dramatically different from prices of competing bidders for similar equipment.
■ Be sure the contractor obtains a building permit, if required.

Concentrator Solar Technologies

Concentrating solar power (CSP) technologies concentrate solar energy to produce
high-temperature heat that is then converted into electricity. The three most advanced
CSP technologies currently in use are parabolic troughs (PTs), central receivers (CRs),
and dish engines (DEs). CSP technologies are considered one of today’s most efficient
power plants; they can readily substitute solar heat for fossil fuels, fully or partially,
to reduce emissions and provide additional power at peak times. DEs are better suited
for distributed power, from 10 kW to 10 MW, whereas PTs and CRs are suited for larger
central power plants, 30–200 MW and higher. Figure 6.8 illustrates a passive parabol-
ic concentrator used in solar electric power–generating plants.
The solar resources for generating power from parabolic CSP systems are very plen-
tiful and can provide sufficient electric power for the entire country if the systems could
be arranged to cover only about 9 percent of the state of Nevada, which would amount
2
to a 100-mi plot of land. The amount of power generated by a CSP plant depends on
the amount of direct sunlight. Like photovoltaic (PV) concentrators, these technologies
use only direct beams of sunlight to concentrate the thermal energy of the sun.
The southwestern United States potentially offers an excellent opportunity for
developing CSP technologies. As is well known, peak power demand generated as a
result of air-conditioning systems can be offset by solar electric power–generating
system (SEGS) resource plants that operate for nearly 100 percent of the on-peak hours.
CSP systems can be sized from 2 to 10 kW or could be large enough to supply grid-
connected power of up to 200 MW. Some existing systems use thermal storage during