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effective to install PV systems even very close to high voltage power lines
than to install transformers to step down the voltage (Sandia National
Laboratory, 1990). Strategically located grid-connected PV in the north-east
USA and south-east Canada could have prevented the cascading blackouts in
that area on 14 August 2003 (Perez & Collins, 2004). This report shows how
dispersed PV could have reduced the huge regional power transfers that were
needed to service air conditioning in load centres such as Detroit, Cleveland,
Toronto and New York City.
x Grid backup—PV-battery grid backup for important equipment in case of
poor grid reliability, particularly in developing countries, but also for
computer systems and emergency power generally in commercial buildings
(Varadi & Braun, 2003).
x Telemetry and metrology—for powering sensors where grid power is too
expensive or too insecure (Varadi & Braun, 2003).
PV systems for distributor feeder support are discussed later in this Chapter, while
many of the stand-alone systems were discussed in previous Chapters.

As environmental factors are increasingly included in the economic analyses
undertaken by utility planners, an increasing adoption of PV technologies is likely.
For instance, a recent study of air emissions from various generating technologies
(Rannels, 1992) concludes that photovoltaics can cost-effectively displace existing
fossil fuel generating plant, if offsets for emission reductions are given.

Despite the apparent opportunities and benefits of PV use, most electricity utilities are
faced with a number of perceived risks, which they have no historical basis for
quantifying, when assessing the feasibility of photovoltaic systems. These include
(Ibid.):
x technical risks—the possibility the system will not perform as specified
x construction risks—the possibility of cost overruns, or inability to meet the
construction schedule
x operating risks—the possibility of breakdown or unavailability of power
when needed
x regulatory and tax risks—the possibility of changes that may disallow tax
credits, accelerated depreciation rates etc.
x financial limitations—high costs of finance, based on the above perceived
risks.
Until a number of demonstration systems have been operated under utility conditions
in each jurisdiction, overcoming these perceived risks to the satisfaction of most
utility planners will be difficult. Nevertheless, the continuous increase in PV system
databases is assisting utility acceptance.

10.4 DESIGN ISSUES FOR CENTRAL POWER STATIONS

Despite the relative ease of installation and cost effectiveness of the small, distributed
PV systems discussed above, much utility interest in PV to date has centred around
the development and testing of central, grid-connected PV stations, since most
utilities are more familiar with larger scale, centralised power supplies. These larger

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