FoxESS Community - Owners & Installers Forum

We had 16 x 385 Watt JA solar panels with a 5 kW (H) - 1P FoxESS Inverter - H1 Series installed last September.

They're on a 39 degree sloped roof at 25 degrees off due south, unshaded (by this stage of the year).

Am I being optimistic to expect the full 6.16 kW out of them? According to the FoxESS website readings today, very bright with little cloud, the most I've seen is 5.19kW, the highest ever being earlier this week at 5.47kW.

I started off thinking "it's only half or one kW", but that's 10-20% off the rated figure.

Is there something else I should be considering or does this indicate there might be something wrong? The original forecast used the 6.16kW figure, adjusted by degredation and shading, neither of which should have been a problem this week.

If you have a 5Kw inverter then that's about it's max although you might get a little over it won't go much above.

In my opinion the main reason for having more panel KW than Inverter is during the rest of the year when you don't have as much sun, with more panels you will be getting a higher output. i.e. if you had 5KW of panels then at the height of summer that's the max you could get but in spring or autumn you might only get 80% or 5KW. If you have 6Kw in summer you will peak at 5KW due to the inverter but spring / autumn you would get 80% of 6Kw which is 4.8KW so your average output would be closer to 5KW/hr during more of the year by having 6KW of panels.

Hope that makes sence?

The inverter is limited to 5kwh of ac output, the inverter is able to boost the output if you have home use as well so you should see a little bit more than 5kw (usually up to 5.4kwh...ish...) but your export has a hard limit of 5kw.

If you have batteries, once the export limit has been met and your home use covered - as long as they still have capacity they will take any unused generation (solar=dc), but once charged you will be limited as the inverter cannot exceed it's ac limit by more than a small amount.

As has been said, oversizing panels is a good strategy to provide more output during cloudy days and also when the panels get hot they will derate - Given summer temps I would suggest peak panel output is probably going be May/June.

Thanks both.

Yup, I can see the sense of the "oversizing" of the panel output.

Dave, charging the batteries has priority over export, doesn't it? That's certainly what I think I'm seeing. Excess after the batteries have fully charged also goes to the hot water by the iBoost before export too I believe, although I'm not sure how to check on that.

MarkRS wrote: ↑Sat May 27, 2023 9:42 am Dave, charging the batteries has priority over export, doesn't it? That's certainly what I think I'm seeing. Excess after the batteries have fully charged also goes to the hot water by the iBoost before export too I believe, although I'm not sure how to check on that.

Yes charging the batteries takes priority over export when the work mode is set to Self Use, but if you change it to Feed-in First the inverter will prioritise the home load, then export and only when you're 5kw export limit is met would it put the remainder into the batteries.

Your iBoost will kick in when it sees sufficient export so normally (Self Use mode) it would come in when the home load is covered, and the batteries are nearly charged as it starts to export.

When you switch to Feed-in First you are effectively making the batteries the lowest priority so you would get your home load covered, your water heated and the export limit covered before you start to charge the batteries.

I've not seen anywhere to switch between self-use and feed-in, not that I want to. Out of interest, where is that?

Hi Mark,
The work mode can be set laboriously on the inverter panel - see Will's good Youtube presentation on all the settings.

I use the web-based access to the cloud server and it is easy, once you find an odd little blue icon on the bottom right of the Inverter mimic in the Energy Flow diagram. The cursor switches to a finger if you hover over it and it opens the work mode menu (though some options are not yet possible/implemented)

I have highlighted the specific bit on this image, which I hope helps.
,

Alan

Thanks for that Alan. I noticed that icon recently (it is fairly new, isn't it?) but hadn't pressed it.

I'm happy with self-use, certainly for the moment. Bit upset to hear that I might not be able to self-identify as a power station though