3 panels east 3 south, Tigo Optimisers and their reliability.

[ChrisJEvans]

Lower power inverter is fine. 3.6kW is perfect for most people. Your panels won’t generate their rated power very often or for very long because in summer they’ll get too hot, and at other times of the year the sun won’t be intense enough or at the right angle.

Under NOCT conditions your panels are 32.96Vmp, making 3 of them 98.88V. If your inverter MPPT works down to 90V then you’ll be fine, but if it only works down to 120V (or anything else higher than 100V) it is likely not to work very well.

o.k. so as the Solis says 90-520V MPPT voltage range I could put 3 east facing 98.88V on one string and 12 south facing 395.52 n the other string and not need to use any optimisers?

Nowty: I see you are suggesting 6 and 9 I know it sounds more balanced but as I'd have to compromise the design I'm not sure.

Really glad I found this forum I tried another but didn't find it at all helpful. Thanks guys you are great.

[Stinsy]

Lower power inverter is fine. 3.6kW is perfect for most people. Your panels won’t generate their rated power very often or for very long because in summer they’ll get too hot, and at other times of the year the sun won’t be intense enough or at the right angle.

Under NOCT conditions your panels are 32.96Vmp, making 3 of them 98.88V. If your inverter MPPT works down to 90V then you’ll be fine, but if it only works down to 120V (or anything else higher than 100V) it is likely not to work very well.

o.k. so as the Solis says 90-520V MPPT voltage range I could put 3 east facing 98.88V on one string and 12 south facing 395.52 n the other string and not need to use any optimisers?

Nowty: I see you are suggesting 6 and 9 I know it sounds more balanced but as I'd have to compromise the design I'm not sure.

Really glad I found this forum I tried another but didn't find it at all helpful. Thanks guys you are great.

Correct! You can go 12x panels one string and 3x panels in the other string with that inverter. No optimisers required.

You got lucky with an inverter with such a wide MPPT range. Maybe the modern ones have a wider range? 120-450V used to be typical.

[ChrisJEvans]

Actually I've just spotted the Solis data sheet says: Start-up voltage 120V
so 4 panels would only just be within spec 5 or 6 it will have to be.

[nowty]

Actually I've just spotted the Solis data sheet says: Start-up voltage 120V
so 4 panels would only just be within spec 5 or 6 it will have to be.

The open circuit voltage should start it up with 3 (just), but if its like my SMA inverter then once the other MPPT starts, the second MPPT does not need to reach starting voltage to start contributing.