question

Aeroid avatar image
Aeroid asked

MPPT sizing (15 x 425W)

Hi,

following the MPPT calcuator, it seems possible to put 15 Panels (JA Solar JAM54S30 LR 425W, ) into three parallel sets with five panels in series each. If I understand the calculater correctly, it suggests SmartSolar 250/100 (128-210V / 91-118A) ... ignoring the cabling for now, how does this comply with the 70A PV input limit of the SmartSolar (Tr)?

Does it simply cut of at 70A and I only need to worry about the cables/junction box (30A MC4 limit)?

Thanks, Gunnar


JA Solar JAM54S30 LR 425W:

  • Open Circuit Voltage(Voc): 37.37 V
  • Maximum Power Voltage(Vmp): 31.30 V
  • Short Circuit Current(Isc): 14.33 A
  • Maximum Power Current(Imp): 13.58 A
MPPT SmartSolarmppt calculator
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3 Answers
nickdb avatar image
nickdb answered ·

70A Isc is a limit, your panel configuration should not exceed that.

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Aeroid avatar image
Aeroid answered ·

Thanks Nick!

Would you then interpret the MPPT calculators suggestion for the 250/100 differently w/ these settings?

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sharpener avatar image
sharpener answered ·

3 strings of 14.33A short circuit current will be max 43A in total which is comfortably lower than the 70A limit.

Probably a good idea to bring all three strings back separately from the roof to the DC isolator. Both to minimise voltage drop and so if you have a fault on one string you do not lose all the PV generation.

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