Confirm installer advice please

[up_north]

As I think I’ve said on previous posts, we’re looking at a 10 panel system but 4 panels will be in shade from a neighbouring property till about 9.30am. The installer has suggested a GivEnergy inverter which has two MPPTs. My logic says (excluding optimisers for now) to put 6 panels into one MPPT and 4 into another. But the installer says that GivEnergy state it has to have the same number of panels going into each MPPT. I understand it might be the case that there has to be the same number on multiple strings going into a single MPPT but this is different.

I did query how they would configure a two array east/west system with different sized roofs but he didn’t really give an answer.

Any advice appreciated. Ta!

 

[binky]

Drivel, the MPPTs are independent of each other, and part of the reason for that is so you can have different numbers of panels on each string. SMA used to offer 3 MPPTs, the third being designed for around 4 panels max to cope with awkward roof spaces.

Juts make sure 4 panels is enough to meet the minimum voltage for the MPPT to get going.

 

[up_north]

Thanks Binky. Your last line has me a tad concerned. I’ve attached specs from the panels and Giv pEnergy inverter. If I’m reading it correctly then 4 panels will barely be enough to get past the 150v minimum for the MPPT, let alone the inverter startup. It’s interesting that the equivalent Solis inverter needs only a 120v startup and the MPPT range starts from 90v.

 

[binky]

it will definetly struggle with those numbers, one of the reasons I like Solis is the lower voltage. I suspect your installer also knows this hence the BS about even strings. Lower start up voltage just means the system gets going earlier and finishes later. Now in reality the difference is small in the grand scheme, but every watt counts in my book

 

[up_north]

Thanks Binky. It’s only when you hear ‘by the way’ type comments from people such as yourself that you start to understand how complex the whole solar/battery thing is so I really appreciate your input. I’m wondering now if it makes more sense to put all 10 on one MPPT and hope the Tigo optimisers do their thing for the shaded panels.

I do have a quote for a Solis based equivalent system but it’s £1200 more and uses a Puredrive battery for which I’ve seen very few independent reviews.