FoxESS Community - Owners & Installers Forum

We have a 11 Canadian Solar 435 w panels on a single string with a Fox H1 gen2 3.6 k inverter facing South @ 32 degrees Because of serious shade issues from adjacent trees all panels have Tigo TS4 AO optimisers fitted. On most days the system works as expected but on clear sunny days as the panels progressively come out of shade (remaining panles in dappled shade) there is a 'bottleneck' where PV production is limited to around 500 watts despite 6 or 7 panels beeing in full sun. Then when the 7th or 8th panel is fully out of shade (it varies) production increases suddenly to the expected 3 plus kw. The problem is most pronounced in Spring and Autumn.

I have also attached a composite image of solar generation graph from Sunday, 26/4/26 overlaying generation graph from Saturday 25/4/26

- Sunday, 26/4/26 - hazy sky (high variable cloud between 1.30 and 3.50 and again after 4pm)

- Saturday, 25/4/26 - clear and sunny all day

As you can see there is a significant reduction in generation over 4 hours in the late morning when the sky is clear and one would expect better generation.

NB There is a small peak at 9 am as sun hits top 3 panels which then become shaded agin until around 11 am. Then all the panels become progressively unshaded until 5pm when whole array becomes shaded again.

Any thoughts as to what may be happening and whether there is a fix eg splitting into 2 strings?

Thanks for your help