Page 186 - Applied Photovoltaics

9.2 RAPS SYSTEM COSTS
RAPS systems vary widely in size, configuration and cost. At the time of writing,
turnkey off-grid system prices were found to be in the range A$18–24/W p for systems
up to 1 kW p and A$12–18/W p for larger systems. The average off-grid system price
was estimated to have fallen to around A$20/W p from a peak of AU$30/W p for 1997–
1999 (Watt, 2004b). Installation costs can also vary substantially depending on site
characteristics and accessibility.

9.3 PORTABLE RAPS SYSTEMS
There are numerous situations where portable RAPS systems can be of value owing
to their independence of existing infrastructure, speed of installation and their
modularity. Systems on standby can be of great benefit for temporary relief during
maintenance or for aid purposes for workers and victims devastated by disaster
(Kubots et al., 1993). Similar systems can be used by groups or communities
preferring nomadic lifestyles to increase their independence and general quality of
life.

9.3.1 Portable systems for remote aboriginal communities
Transportable photovoltaic DC power supply systems were developed in Western
Australia for installation in remote Aboriginal communities with no access to grid
power (Department of Primary Industries and Energy, 1989). The systems supply DC
power for refrigeration, communications and lighting, and limited AC power for hand
tools, televisions and video equipment. Other potential loads include water pumping,
cool ro`oms, evaporative coolers and tyre inflating equipment.

The photovoltaic power supply and all the loads are supplied in a self-contained
‘Solar Pack’. The systems are durable, have low operational costs and require
minimal maintenance. They are supplied with the aims of improving Aboriginal
health, independence and general quality of life. The conventional approach for
supplying power to these remote communities has been via a diesel generator. This
has largely been unsatisfactory because of the:
x expensive and often logistically difficult transport of fuel by road
x frequent maintenance requirements
x inflexible system output, which cannot be adapted to changes in the size of
the community
x difficulty in transportation
x noise.
The transportable Solar Pack overcame many of these problems. Typical system
components include:
x photovoltaic array in range 500–1350 W p
x battery of deep-cycle lead-acid traction cells configured for 24 V dc
x electronic controller and switchgear to protect and isolate batteries as
necessary, to prevent overcharging and to disconnect non-essential loads
during poor weather
x 100 W VHF transmitter-receiver for communicating with the flying doctor
and other vital services

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