scope:

This part of IEC 62257 specifies the general requirements for erection and operation of PV arrays in decentralized rural electrification systems.

This technical specification contains requirements for ELV and LV PV arrays (see Table 1). Particular attention must be paid to voltage level, as this is important for safety reasons and has an influence on protective measures and on the skill and ability level of people operating the systems.

For the sake of completeness, this technical specification gives requirements for d.c. voltages below and above 120 V. However for rural electrification projects it is strongly recommended to choose a voltage in the range of extra low voltage, taking into account the assumed skills of the operators, installers and users. Nevertheless, designers must be aware that decreasing the voltage means increasing the current and thus transferring voltage hazards to current risks (risk of fire, etc.).

The following PV array configurations are considered (see Figure 5 to Figure 7):

a) single string of modules;

b) multi-string PV array;

c) PV array divided into several sub-arrays.

Direct current systems, and photovoltaic systems in particular, pose various hazards in addition to those derived from conventional a.c. power systems, for example the ability to produce and sustain electrical arcs with currents that are not much greater than normal operating currents. This technical specification addresses those safety requirements arising from the particular characteristics of photovoltaic systems.

The aim is to provide safety and fire protection requirements for:

− uninformed persons, including owner(s)/occupier(s) and users of the premises where photovoltaic arrays are installed;

− informed workers (e.g. electricians) working on these systems; and

− emergency workers (for example fire fighters).

For installation of PV arrays see IEC 60364-7-712.