This section performs automated calculations, and validation checks at the string, sub-array and array level to ensure compliance with Section 712 of BS 7671. Depending on the system’s configuration, it evaluates key protection criteria, including:


  • Protection of PV modules and strings (Reg. 712.431.101 and 712.431.102):

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  • Choice of protective devices in line with IEC 62548:



  • Protection of PV string cables (Reg. 712.433.101):



  • Calculation of maximum open-circuit voltage and short-circuit current (Reg. 712.433.101.1): 



  • Protection of PV sub-array cables (Reg. 712.433.102):




ElectricalOM automatically highlights any violations or non-compliance, supporting accurate and regulation-compliant PV system design (see Figures 18 - 19).


A screenshot of a computer program??AI-generated content may be incorrect.

Figure 98 Overcurrent Protection Checks for a PV System with 3 Strings and Integrated Power Optimisers (No Additional String Protection Required)


A screenshot of a computer??AI-generated content may be incorrect.



A screenshot of a computer??AI-generated content may be incorrect.

Figure 19 Top: Overcurrent Protection Checks for a PV System with 3 Strings without Power Optimisers, Middle: Tooltip Warning Message – Overcurrent Protection Required for Each PV String (Reg. 712.431.101), Bottom: Warning Area Message – Overcurrent Protection Required for Each PV String (Reg. 712.431.101)


Figures 18 and 19 illustrate different outcomes resulting from the use of power optimisers. In Figure 18, the system features optimisers that block reverse fault currents, enabling the PV strings to operate without requiring additional overcurrent protection. In contrast, Figure 19 depicts a system lacking optimisers, where the calculated reverse current exceeds the allowable limit, triggering a non-compliance warning under Regulation 712.431.101 and requiring separate protection for each PV string.