10kW Inverter Tripping / 14.5kW of panels..?!

I have just had an installation completed. I have 33xJinko 440W panels (14.52kW (about 10kW facing West / 4.5kW South) feeding via 3 strings into a Fox ESS 10kW AC inverter into the AIO gateway. Today (The sunniest day yet), the 32A breaker in the gateway tripped, leaving the Fox ESS with a Grid Lost Fault.

My question is: seeing as my generation is peaking around 10.3kW, and today, for the first time, this? Could this have caused its 32A breaker to trip, or did its 32A breaker cause it to trip? It needs to be updated to a 45A.

Is that inverter inadequate to handle the system? I presume I am wasting those additional panels on the roof in the height of summer only as an additional export, but they will pay me in the winter, as I'm not overpowering the inverter, such as a 15kW during sub-optimal production.

ANT80 My question is: seeing as my generation is peaking around 10.3kW, and today, for the first time, this? Could this have caused its 32A breaker to trip, or did its 32A breaker cause it to trip? It needs to be updated to a 45A.

My schoolboy physics remembers W=VA, so rearranging A=W/V = 10300/250 (guessing your voltage was high with all that generation, but check what it shows in the logs), so A=41.2

At the point, it tripped - 10308W / 254.7v Yep - 40.47A.

Is a 32A breaker fitted because the cabling used is rated at 32A? Maybe someone (your installer?) didn't do the load calculation correctly. Just changing the breaker isn't necessarily the right thing to do. You might have to limit your inverter to 8KW which would be a shame.

40A / 9.2kW is pretty much the accepted max the gateway can be upgraded to.
(Glossing over the fact that the Gateway (if its a newer one) says 21.7A PV input on the sticker on the side, despite coming factory fit with a 32A...)

FYI you may find transition into and out of island mode may not be very smooth at high PV output >6kW.

Breakers are installed to protect cables. If the device output is greater than the cable can take, then the cable is undersized.
Dont want cables going up in smoke and starting a house fire

I would suggest that you might need multiple breakers run to multiple inverters or different way of doing things.

Possibly take south on one inverter to feed the gateway and leave the other grid tied with a stand alone g100 device to manage export?

15kVA of PV is equivalent of a 60A domestic supply that powers some houses from the grid.

Not being rude, but has your installer done the correct g99 paperwork and got DNO approval?

hoggy FYI you may find transition into and out of island mode may not be very smooth at high PV output >6kW

For my education, would you be able to expand on that?

CW the AIO can only absorb 6kW MAX charge during island mode only times - so if you PV side is outputting more than this it'll trip the AIO (because theres nowhere else for the power to go as the grid connection is severed)
The AIO will trip off, which will take your whole house off and then reboot itself about 30sec later. Depending on how full your battery is this cycle may well repeat until either the battery is full (where it'll switch to 54Hz mode and power down your PV inverter) or the grid connection returns.

Hence the (undocumented) "limit" of about 5kW of PV attached to the gateway ensures this doesn't have the chance of happening.

It is my understanding that the Tesla Power Wall actually throttles the pv inverters slowly by gradually increasing frequency rather than going straight to 54 Hz, which just shuts the inverters off entirely. This way you can keep solar, but it is reduced in output in reaction to the frequency. Perhaps this is a sensible approach to avoid the need for a 5 kW max input that AIO should make as well.

MMitchy adaptive Freq control rather than the abrupt On/Off 54Hz jump was a coming soon feature...

hoggy "coming soon" after they saw how PW's worked 😉

One of the reasons our installers still won't touch AIOs - that and the N-E fiasco and the ongoing inability of GE to make two work together (as was promised at installer launch presentation). They're not alone either...

kram they did. The G100 was rejected and the G99 DNO signed off on 5kW.

hoggy generally I'm pulling around 10kW through the AIO charging the battery around 6kw, powering the house at around 1kW, and exporting the remainder, all day long so I'm not sure where this is coming from. I think we just have an under rated breaker on a maxed capacity FOX 10kW pre gateway inverter. Fully agree with comments that the wiring for the 3 strings and the wiring from the inverter to the AIO Shoukd be rating checked, which I will insist upon. Not sure there is anything more sinister than that.

ANT80 it's in Island mode I'm talking about.
Turn your grid supply off in those 10kW high PV times, and it will go onto fault.

By all means try but I'd not be surprised if Giv come back with a No on fitting anything bigger than a 40A breaker.

hoggy ahh I see what you mean now. And yes, Giv advised, 'The breaker should be 40A; you can swap the breaker for a C40 type A RCD/MCB. OR can you remove it and replace it with a DS201 C40A30 and a two-way blank

hoggy

MMitchy

It does exactly that, although only with “approved” inverters.

ANT80

So has the g99 at 5kW got a 5kW inverter limit or is it no limit on the inverters (eg you’ve said fox + gateway and the limited 5kW export)

From what you said about g100 being rejected then it sound a like the first. If it is that then you have a problem as your total permitted inverter capacity is 5kW between everything.

If that is the case your solar inverter can’t be more than 5kW and you will have to use a DC coupled battery.

It appears then that the inverter should have an internal limit that stops exports going above 5Kw. Uprating the GE breaker isn't necessarily the solution. But it does seem to be a shame to have such a large array and high power inverter unless you can divert the excess above 5Kw into batteries or the house. Is that what you mean? When exporting less than 5Kw the available 10Kw is mostly used by batteries and the house?

Windy Miller

I’d be interested to see what the g99 says, as the built in export limiting device is a g100 compliant device. Hence no to g100 could mean no to such a setup.