BS IEC 62548:2016 pdf free download – Photovoltaic (PV) arrays – Design requirements
5.1.4.2 PCEs with separate maximum power point tracking (MPPT) inputs
Where PCE’s provide separate maximum power point tracking inputs, the overcurrent protection of the section of the array connected to those inputs shall take into account any backfeed current as required to be specified by IEC 621 09-1 and IEC 621 09-2. Each PV section connected to an input (refer to Figure 5) may be treated for the purposes of this document as a separate PV array. Each PV array shall have a switch-disconnector to provide isolation of the PCE. The provisions of multiple switch-disconnectors in 7.4.1 apply, and a warning sign as required in 1 0.5.2 shall be provided.
5.1.4.3 PCEs with multiple inputs internally connected together in the PCE
Where a PCE’s multiple input circuits are internally paralleled onto a common DC bus, each PV section connected to one of those inputs (refer to Figure 6) shall be treated for the purposes of this document as a sub-array, and all the PV sections combined shall be classified as the complete PV array. Isolation of the PCE shall be provided, either by one array switch disconnector for the complete PV array or sub-array switch disconnectors for each sub-array. Where multiple switch disconnectors are used the provisions of multiple switch-disconnectors in 7.4.1 .3 apply and a warning sign as required in 1 0.5.2 shall also be provided.
5.1.5.1 General
In some array designs DC conditioning units (DCUs) may be connected to individual PV modules or small groups of PV modules to allow DC conditioning of the PV output or allow for automatic shutdown of the output under certain defined conditions. Figure 7 shows an example of this type of configuration.
5.1 .7 Batteries in systems
Batteries in PV systems can be a source of high prospective fault currents and should have fault current protection installed. The location of fault current protection related to battery systems is generally between the battery and charge controller where fitted and as close as practical to the battery. This protection can be used to provide overcurrent protection for PV array main cables provided the PV array main cable is rated to withstand the same current as the battery overcurrent protection device.
In the design process, the sizing of cables within the array and in cable connections from the array to the application circuit affect the voltage drop in those cables under load. This can be particularly significant in systems with low output voltage and high output current. Pollution of the surface of PV modules caused by dust, dirt, bird droppings, snow, etc., can significantly reduce the output of the array. Arrangements should be made to clean the modules regularly in situations where significant pollution may be a problem. The cleaning instructions of the module manufacturer, if any, should be considered.