FoxESS Community - Owners & Installers Forum

Hey clever folk.

I have 4x Trina Vertex S+ 445w south panels on 1 MPPT of my G1 H2 5kw inverter
I have 3x Trina Vertex S+ 445w north panels on the other MPPT.

All panels have Tigo optimisers. None of the panels are in any shade or have any shading issue (north panels early in the day are in the shade)

Please see my attached pics, with the sun pretty much directly overhead my north string voltage is soooo much lower than the south facing panels (yes the south facing panels have 1x more panel but there is still a big difference)

I have removed all the optimisers on the north panels, the voltage has stayed the same.

I have tested all the north facing panels individually, after disconnecting them, I get about 50v on each of them.

In another picture, the sun has disappeared, basically no generation, yet the south panels have a significantly higher voltage on the string still.

Any advice?

The Fox inverter won’t start up the MPPT with only 3 panels on one string, it’s not just the voltage it has to be able to balance the MPPT with the string impedance to achieve power at the most efficient point ~ and that will reduce the voltage, in this case it will not be able to start up as it is unable to find an impedance that allows enough voltage and power at the same time.

My minimum recommendation is 4 panels per string, 5 if possible particularly with optimisers.

Thanks Dave, really interesting. I am about to add 1 or 2 East facing panels to that string so it will solve that.

However you can see in one screenshot the string is producing 400w, therefore is working?! Just poorly!

The MPPT's have to find an impedance that allows enough voltage to start up and to allow power at the same time, if it does start up, it appears likely it can only do that at your panels optimum power but it cannot be effective and will for most days not start up at all.

That’s great info. Thank you