Overpowering solar inverter

[barnaby91]

Hello,

My current 2.5kW Solar pv array is in a less than favourable position, but there is plenty of space to expand the array. I have an additional 4kW of solar panels that I wish to add to the array as even during peak production we are lucky if we can achieve 1800W out of the 2.5kW so looking at overpowering the inverter.

Currently the array is connected to a SAJ 3600W inverter, but this has a max Vdc of 580V and Isc Max of 15A. If I overpower the inverter, from what I have read the max voltage must be adhered to, whereas the Isc can be over with parallel strings. (Solar panels have an Isc of 8.65A so will be over if I combine the strings.)

Alternatively I have a sunny boy 4000 inverter with two MPPTS, 2 x 15A. A quick question, does the Vdc max of the sunny boy get split between the two mppt (halving the max Vdc per string? Or are the two strings able to have 750v and the 15A each?
Thanks

 

[kropaske]

You must always adhere to manufacturer specification. Specs will tell you max Vdc input from array, max Vdc per MPPT, max Isc and max recommended PV input power. With Isc you have to apply 1.25 factor to it as panel specs are given at standard test condition and at certain times they will generate more current then advertised. So for example if your string Isc is 10A then mppt Isc should be minimum 12.5A.
Looking at the specs of sunny boy, max input voltage is 750V which I would assume is for whole array as mppt voltage range is given at 175-500V. String voltage Does not have to be split 50/50 as long as you are within the range.

 

[SWDweller]

Connecting the inverters in parallel does not guarantee that the electrical circuit will see the circuit as parallel. Path of least resistance