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Figure 6.1. Possible uses of photovoltaics on and off the central grid.

                          In the US in 1991, a PV system could be cost-effective if the grid extension was more
                          than 5 miles and the load was less than 1500 kWh/month, typical of two houses
                          (Rannels, 1991). Smaller 2 kW systems could be cost effective at grid extensions of
                          only one third of a mile (Ibid.).

                          6.2    STAND-ALONE PV SYSTEM DESIGN
                          The design of a stand-alone PV-based power system is determined by the location,
                          climate, site characteristics and equipment to be used. The selection and
                          interconnection of system components will be discussed in this chapter and design
                          procedures in the next. Unless stated otherwise, the comments on storage refer to
                          lead-acid batteries. Fig. 6.2 shows a schematic of a typical PV-based stand-alone
                          power system.

                          Many countries and regions have produced standards and/or guidelines for PV
                          systems over the last decade, and the applicable ones should always be understood
                          and followed by designers and installers. Sometimes, compliance is a condition for
                          subsidies or other forms of financial support. In Australia, the primary standards of
                          interest are the AS4509 series of three standards (Standards Australia, 1999–2000a,
                          1999–2000b, 2002). Other standards apply to system components and particular
                          aspects, some of which are mentioned below and/or listed in Appendix E.








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