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Optimum PV string size using roof mountings on NE and NW rooves at right angles.


DocFrank
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I have worked through Gerhardt’s helpful post but I do need some extra specific help. Can anyone help me please. I am going for the same/similar Sunsynk 5.5kW super hybrid inverter and the ZTE ZXDC48 FB101 4.8kWh Li battery but planning to use the maximum strings of Canadian solar 410W super high power PERC with MC4 panels (ie 8 in each string) but my installer thinks 16 PV s are too much even though the 1 string will face north-east and the other north-west (90 degrees to each other). He warns that I could generate an over voltage in the system and fry my inverter. So this is my dilemma and I am hoping someone clever may be able to help me solve it. (I think this system will be optimum. The installation will be near Howick in KZN.) Thank you.

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1 hour ago, DocFrank said:

He warns that I could generate an over voltage in the system

These panels have a maximum open circuit of around 47.6V at 25C which will go up to about 50.5V at 5C.  8 Panels in series will hence have a maximum of 404V, well under the inverter's maximum MPPT voltage of 425V. 

16 panels @410W would be just over the maximum of 6500W allowed, but as you correctly say with the panels at different orientations you will never get there. (If you let me know the inclination of the panels I can generate a graph of your potential solar production for you)

Assuming that I looked at the correct data sheets, you system would be nicely optimised.

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On 2020/10/07 at 11:08 AM, Calvin said:

If you let me know the inclination of the panels I can generate a graph of your potential solar production for you

Below the graph as promised for your 26 degree roof angle.

image.png.a976218717d4d0444dcd6aded0848558.png

Peak production would be about 0.97W per W installed, or 6.36kW.

Note that all these figures are at 25C panel temperature.  Actual production would be about 10% lower at 55C and 7% higher at 5C.

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