Slow Recovery & Reduced Yield After Grid Outage on T15-G3

[itzAltaf]

Dear FOX ESS Support Team,

I am using a FOX ESS T15-G3 on-grid inverter with 10 × 585W BF Jinko panels. I’ve observed that even brief grid outages (5–15 minutes) cause a disproportionately large drop in total daily production, even though weather and irradiance remain consistent.

For example:

• On May 25, the grid was out from 07:46 to 07:51 AM. Total production: 23.6 kWh.

• On May 26, outage from 11:23 to 11:42 AM. Total: 27 kWh.

• On May 27 (no outage), production: 31 kWh.

Based on app monitoring and performance tracking, I’ve noticed:

• The inverter takes several minutes after grid restoration to stabilize and resume full output.

• It seems to re-scan MPPT tracking from scratch, instead of continuing from previous optimal values.

• This behavior causes underperformance far beyond the actual outage duration.

I’d like to know:

• Is this behavior expected with the current firmware?

• Are there any firmware updates available to optimize post-grid-outage recovery?

• Can you recommend settings or configurations to improve MPPT retention or re-connection time?

I am quite worried about this behavior of inverter as grid outage for short period of is common in my area. and this impacts significantly power production.

Thank you in advance. I am attaching screenshot of graph for better understanding.

Regards

[Will]

From my understanding to it inverter is working as expected. It can’t simply resume from the previous values. Should only take minutes to resume.

[itzAltaf]

Right, So grid outage would result significant/huge reduction on total production/day ?

If grid outage is around 8AM then that day peak is 3.5KW
and without grid outage peak value is 4.5KW.

is it normal for fox inverter ?
because my another system (Inverex Brand) doesn't give such bad performance for same condition.

EDIT: I expect inverter to take time to resume but why it doesn't get to usual peak production around?
Moreover, please guide me about official support/company's warrant claim dept ?

[itzAltaf]

Bump

[Will]

Doesn't make sense, the mppt should ramp to full speed within a few minutes, an outage in the morning shouldn't cause a limit all day.

I would double check you're on the latest firmware and then carry out a full restart of the inverter and monitor.

[itzAltaf]

Doesn't make sense, the mppt should ramp to full speed within a few minutes, an outage in the morning shouldn't cause a limit all day.

I would double check you're on the latest firmware and then carry out a full restart of the inverter and monitor.

Thank You
Below is detail of inverter firmware data.

Please advise what should I do next ?

can I upgrade firmware on my own if update available ?

[Will]

Hi, those appear to be old firmware versions. Only your installer or fox support can update the firmware. It's not yet end user accessible.

[itzAltaf]

Right. Thanks Alot.
I will try to get it upgraded. Will share details here.