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Solar array sizing help


gav
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Hi,

I want to size my array to try and get as close to maximum as possible. Can someone help to confirm my calculations and thinking are correct?

I have the following specs on my inverter (Luxpower SNA5000WPV):

Max. PV Array power: 6400W
Start-up Voltage: 100Vdc+-10Vdc
Max. PV Array Open Circuit Voltage: 480Vdc
Max. PV Charging Current: 110A

This inverter has two MPPT inputs which can be set up either as "S: two independent String inputs" or "P: same string input for 2 MPPTs". 

If I get 14 x 455W solar panels e.g. Ja solar (Voc 49.85), create two strings of 7 and set the inverter to P: same string input for 2 MPPTs (which I assume takes the strings in as parallel but not 100% sure and it could be other way round) I should get the following results:

Per string -
PV string power: 3185W
PV string Voc: 348,95Voc
PV string Amps: 10.92A

Since the inverter takes these two strings in as parallel the end result should be:

power: 6370W
Voc: 348,95Voc (important not to exceed inverters max 480Vdc)
Amps: 21.84A

Does this seem feasible? Any comments are appreciated.

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41 minutes ago, gav said:

anyone?

I guess that includes me... yes, if Voc is, lets call it 50V/panel and 7 in series, your Voc at around 350V would be well within specs for the MPPT input of your inverter, in fact you could do 9 panels in series, 450V and that should be ok, with a few Volts to spare, maybe go for 8 in series times 2 seperate strings into your inverter, this keeps the current per string lower and thus the cabling sizes a bit more in check.

But your setup should also be ok, as for

On 2021/07/06 at 8:39 AM, gav said:

Max. PV Charging Current: 110A

this would be on the battery end and not on the MPPT input side...

and as for

On 2021/07/06 at 8:39 AM, gav said:

PV string power: 3185W
PV string Voc: 348,95Voc

nope, you'd need to see Vmp in reality, bu that should be close to 3185W/10.92A (assuming that's Imp as in Amps at max power), then the end result should 7 panels worth of Voltage... thus 3185/10.92=291.667V and this divide by the 7 panels is 291.667/7=41.667V app. per panel at maximum power...

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