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ako asked

MPPT Sizing

I have a Blue Solar 150/70 MPPT charge controller , am i correct in saying that the maximum voltage coming into it from the Array can not exceed 150 Volts and the maximum Amps coming into it from the Array can not exceed 70 Amps . I am reasonable confident about the 150 voltage but not so sure about the 70 as someone mentioned that was output not input , if that is correct then how would i work out panel sizes needed as they are given in Volts and Amps , those come from the Panels and go into the MPPT and not the same as what would leave the MPPT . I have used an online string calculator to see how big my panels could be and have no problem keeping the Voltage to under 150 as its just the total of the string voltage times number of strings , is it the same for the Amps ?

MPPT Controllers
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1 Answer
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wkirby answered ·

For the 150/70:
The maximum string Voltage is 150V.
The maximum battery (output) current is 70A, the controller will self limit this, no problem even if array power is higher than output power.
The maximum PV (input) short circuit current is 50A. Make sure your array short circuit current (Isc) is below this value.
Let's imagine a single panel is 40V Voc and 8A Isc.
So, three panels in series will be 120V Voc and 8A Isc.
Three panels in parallel would be 40V Voc and 24A Isc
Nine panels, three in series and three in parallel would be 120V Voc and 24A Isc.

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