Global MPPT KH Series

[Declan90]

Hi,

I've been searching round for a solar solution and have had a quote for a KH Series Inverter and ECS batteries that certainly looks interesting.

Unfortunately part of our roof suffers from some morning shading. A proposed solution is to strategically make use of the 3 MPPTs in the KH series inverter to avoid having to install optimisers.

Query is do the Fox inverters / KH series have a Global MPPT function (i.e. scans full IV curve for true maximum rather than just looking in localised area around expected maximum)? I'll be honest I'm not sure if this is one of those things that has just become bog standard industry wide, but generally speaking appears difficult information to get hold of for any inverter!

Thanks in advance!

[Dave Foster]

Interesting question, I don’t think (many) any manufacturers specify the technology used in their MPPT trackers, the FoxESS has a wide voltage range and in my experience performs well from 5 panels upwards - personally I find the trackers sweet spot to be in the range 250-350V but that’s mostly an observers view of various systems.

You might be better to ping an email to Fox pre sales support to see if they will answer that.

Optimisers are one of those marmite topics, I have always had good experience of them, although they do add additional affects particularly on a smaller number of panels, the Tigo TS4-A-O optimiser is my device of choice for this.

What I can say that the K(H) series is an exceptional inverter, probably the best FoxESS make for domestic use and I would very much recommend it.

[calum]

Hi Dave, I'm still working through the steps of getting our wiring changed to allow EPS functionality, with the possibility of a swap to a higher capacity inverter. The DNO has given us the nod to go up to 6kW, I'm just wondering what advantages the KH might offer over the "normal" H1, given that we don't have a huge system. The difference in retail pricing between the H1-6kW and KH-7kW seems to be ~£200 so not prohibitive if there was some tangible benefit.

[Dave Foster]

Hi Dave, I'm still working through the steps of getting our wiring changed to allow EPS functionality, with the possibility of a swap to a higher capacity inverter. The DNO has given us the nod to go up to 6kW, I'm just wondering what advantages the KH might offer over the "normal" H1, given that we don't have a huge system. The difference in retail pricing between the H1-6kW and KH-7kW seems to be ~£200 so not prohibitive if there was some tangible benefit.

Hi Calum, that's good news, something to look forward to

The K series is mostly about scale for domestic (and commercial) properties - starting at 7kwh and going up to 10.5kw they can handle a minimum of 3, or up to 4 PV strings on the KH9 and above.

I suppose you might they say they are the best of the H series with some improvements, the individual strings can handle up to 16A (only 13A on H series) and with the ever increasing output of solar panels, current (A) rapidly becomes a problem for the H series when you have larger strings. They are better at handling larger arrays so over provisioning is more of a possibility without worrying about errors on the higher generating days.

But their party trick (and I wish I had a property big enough and enough money to afford this) is the ability to handle up to 10 inverters in parallel, load sharing and balancing, standby when not needed etc.. so for those people with large properties, multiple arrays, heat pumps, electric showers etc.. these inverters really deliver.
The other big feature of parallel is multiple battery systems, increasing the capacity from the 33kWh maximum up to an eye watering potential of 330kWh.

There is an H (G2) in the pipeline which offers similar improvements to the normal H series but as yet they're not on sale. If you only need one inverter arguably the Kh7 is better than H6 because it gives you more scope to grow, runs a bit cooler, has a wider operating temperature range, and is a little bit quieter (but you'd hardly notice).

The KH has just had schedules (force discharge etc..) released and the modbus connection to it has been merged into the home assistant integration and so it wouldn't affect your historical data either.

Will has just upgraded to twin KH10.5's (lucky, lucky.....) and has just done a video on them if your interested

[calum]

Thanks Dave, I'll take a look at Will's video.

I suspect we aren't really going to be expanding our system here, we don't have roofspace for many more panels, or garage space for a lot more batteries! But the higher overall throughput is potentially attractive - it also sounds like if it runs cooler, it might have lower idle consumption, and that definitely would be attractive, as the H1 we have at the moment eats about 2.5kWh of our battery capacity every day in the winter months.

[calum]

In case anyone is reading this in the future, one of the very concrete spec bumps the KH7 gets over the H-series is the ability to do 10kW peak AC output (assuming enough battery and / or PV) for up to 60 seconds in EPS mode - essentially a bit of overboost to avoid tripping the inverter with an overload.