Calculator #011 PV String IEC 62548

PV String Calculator — modules per string

Maximum and minimum number of modules in a series string, from the inverter DC window and the module temperature behaviour. The maximum voltage follows IEC 62548:2016, 7.2, by either the manufacturer's temperature coefficient or the Table 4 correction factors; the MPPT bounds come from the inverter data sheet, since IEC 62548 sets no minimum MPP voltage.

Developed by the ieccalc.com engineering team

Questions and corrections — forum

Input

Module Voc,STC, V Open-circuit voltage at STC, IEC 61215 nameplate.

Module Vmp,STC, V Maximum-power voltage at STC.

Voc temperature correction IEC 62548, 7.2 puts the manufacturer route first; Table 4 is the fallback.

β Voc, %/°C Negative for crystalline silicon.

β Vmp, %/°C Used in both routes — Table 4 corrects Voc only.

Minimum ambient temperature T_min, °C IEC 62548, 7.2 uses the lowest daily ambient as the reference.

Maximum cell temperature T_max, °C Design maximum cell temperature under load.

Mounting context IEC 62548, 6.1.1 limits arrays on buildings to 1000 V DC.

Module technology Table 4 applies to c-Si only, IEC 62548, 7.2.

Inverter V_dc,max, V Maximum permitted DC system voltage.

Inverter V_mppt,min, V Lower MPPT window limit, inverter data sheet.

Inverter V_mppt,max, V Upper MPPT window limit, inverter data sheet.

Result

PRO — module schedule and reports

The single string check on the FREE tab is complete and unrestricted. PRO runs the same check across a module schedule against the current inverter window, and exports the editable report formats.

Module	Voc,STC	Vmp,STC	β Voc	β Vmp	N_min	N_max	Verdict

Glossary & abbreviations

Built-in validation tests

Expected values derived by hand from IEC 62548:2016, 7.2 and Table 4. The Table 4 reads are independent of the β arithmetic, so a shifted table row fails them.

#	Case	Quantity	Expected	Computed	Status