How to split 2 string system across 3 aspects

[forrest22]

Hi all, I have a 4.2kW system with 6x West panels (string 1) and 4x South panels (on string 2). These are hooked up to a 4.6kW Solis inverter, and all panels have Tigo optimisers.

I'd like to add some more panels to an East facing roof - there's space for 6 but the inverter only supports 2 strings so what's the best way to wire them up?

I've read on the Tigo website that East/West split only works in specific situations, and even then it's not ideal. So I'm thinking I'll add the panels to string 2 with the south facing aspect. The Tigo website advises keeping the number of panels split like this to within 25% of each other. 4 and 4 would be fine then, but 4 & 5 would be pushing the limit.

Does anyone here have experience with this? Any thoughts/advice much appreciated.

Thanks

 

[wpns]

Pretty sure things get wonky (that's a technical term ) when strings aren't all on the same plane. https://diysolarforum.com/threads/t...optimising-as-hoped.76928/page-3#post-1006553 (long thread, this is the TL:DR) solved a similar problem by moving panels between strings to avoid the multi-plane issue...

 

[forrest22]

That's a little disappointing. I can't split 3 aspects across 3 strings because the inverter only supports 2.

The Tigo website states it should work ok if wired in series (https://support.tigoenergy.com/hc/e...em-for-different-tilts-angles-and-orientation).

It'll overall be a net positive to solar generation, though. We'll lose a bit at the ends of the day but gain much more once the sun is up.

I suppose I could add a second inverter but I can't think of an efficient way to do that.

 

[SeaGal]

I suppose I could add a second inverter

this ^^^^... but it looks like you're progressing down that route anyway, from your other thread.

 

[forrest22]

Yes, indeed. I don't like the idea of a wonky system, it'll just niggle me when things aren't working quite as I'd like. And a small inverter shouldn't cost too much.

It's good to have help with these decisions.