Considering an additional inverter for two balcony mounted panels

[dustmaker]

I have 8 510w east-west panels on a flat roof hooked up to a KH-7 inverter, but these get very little yield in winter months due to the low height of the sun at this time of year. Average yield in Dec was just under 2kwh per day.

I have a south-facing juliet balcony on my loft conversion and had the idea that two near-vertical panels could be mounted, angled slightly upwards, which would get the most of the winter sun.

If I add a small inverter locally for these additional panels, such as a 1.5kw S-series inverter, do I need to connect this to my KH-7 inverter somehow (either through a CT clamp, direct connection between the two, RS485 - have an existing ethernet adapter for home assistant integration, or can they share over the fox cloud?) for the additional generation to appear in my stats, and most importantly, to charge the batteries on the KH-7?

Many thanks
Alex

[evilbunny]

had the idea that two near-vertical panels could be mounted, angled slightly upwards, which would get the most of the winter sun.

Optimum angle depends on distance from the equator, not just time of year.

If I add a small inverter locally for these additional panels, such as a 1.5kw S-series inverter, do I need to connect this to my KH-7 inverter somehow (either through a CT clamp, direct connection between the two, RS485 - have an existing ethernet adapter for home assistant integration, or can they share over the fox cloud?) for the additional generation to appear in my stats, and most importantly, to charge the batteries on the KH-7?

As you pointed out, there is 2 coupling methods, AC with an additional inverter, or DC connected to the inverter connected to the battery.

With AC you would need a CT clamp for the battery to monitor it.

DC is simpler and has less losses since it's not going DC->AC->DC and can still charge during black outs. BUT the inverter we have can be connected to multiple solar arrays, however they have to be the same size and be pointed in the same direction with the same angle.

Otherwise the output from the solar arrays is somehow limited from both systems that I didn't fully comprehend while reading about it in the user manual.

[dustmaker]

Thanks for your very speedy response and your insight!

I did consider a DC run to the existing inverter but would prefer to save the spare MPPT on there for a string of panels on a planned extension.

It sounds like I would need to run a cable for a CT clamp beween the inverters, or are there wireless options that could work (around 20m apart)?

Without the CT cable, what you the KH-7 inverter do? The extra 2 panels are likely to be producing less than the house load a lot of the time (so less concerned about DC-AC-DC efficiency), so would my existing KH-7 just see this as reduced house load and output less from the batteries? Appreciate this would mess up the stats being recorded in terms of overall load.

[evilbunny]

I did consider a DC run to the existing inverter but would prefer to save the spare MPPT on there for a string of panels on a planned extension.

According to https://www.fox-ess.com/Public/Uploads/ ... V1.0.6.pdf

No. of MPP trackers 3

It sounds like I would need to run a cable for a CT clamp beween the inverters, or are there wireless options that could work (around 20m apart)?

Do you need a run that long though?

There already would be a CT clamp monitoring the mains and the other inverters output would have to run there as well.

Without the CT cable, what you the KH-7 inverter do? The extra 2 panels are likely to be producing less than the house load a lot of the time (so less concerned about DC-AC-DC efficiency), so would my existing KH-7 just see this as reduced house load and output less from the batteries? Appreciate this would mess up the stats being recorded in terms of overall load.

When the other inverter is AC coupled it's similar to grid charging.