FoxESS Community - Owners & Installers Forum

Hello folks, first post please be gentle

I have had a Fox inverter and 5KW of batteries since just before Xmas. Before that I had nine panels and no battery; then the same installer swapped our Solis inverter for a Fox one and added the batteries and five more panels, bringing the total on the roof to 14. Everything worked fab until late May...

On and before 25-May, we had the expected output trace – a nicely curved "blob" slowly increasing from 8AM to a 1230 peak @4.8KW approx., then slowly decreasing until 5 or 6PM.

But since 26-May I have had a strange "stepped" output trace and much reduced power generation. On a perfect sunny day, output gets to 1.7/1.8KW by 0930ish and stays flat for a couple of hours, then shortly before midday it suddenly shoots up to 3.2KW where it again stay flat until it starts decreasing as the sun goes down. Please see attached screenshot of yesterday's trace. And as I type this, exactly the same thing has just happened at 11:40 - one minute we were generating 1.8KW, the next 3.2KW with no change in conditions. But it'll stay here now an hour or two before starting to decrease, it definitely won't hit the 4.8KW high at 1230ish we were enjoying a month ago.

In Settings, max is set to 6000W and 100%.

Previously we had some Error 28 Av Grid Volt faults, now resolved by upping the setting as directed by my installer.

My installer emailed Fox Technical Support and they pointed at the ambient temp / inverter temps going too high in the hot weather. But this started happening late May. The last three days I've been running a fan over the inverter and it is reporting ambient and inverter temps lower than they were in May when we were getting no steps and 4.8KW peak.

I believe my inverter is faulty and broke on or around 26-May when these strange output traces started happening and max power generation reduced by approx. one third. I am sooooo frustrated that despite the ongoing stunningly perfect conditions, on days we use the oven we run out of battery power in the middle of the night and start importing from the grid, despite our £10K investment

Any and all advice gratefully received. Thank you.

Dan

Update: I've emailed Fox Support. If anybody else has seen output traces similar to mine I'd love to hear about it please. Today the same again - 1.7KW PV output all the while the battery was changing and for 20mins afterwards; then suddenly PV leapt to 3KW (which is yay, but just 60% of potential) and held for an hour or so, and is now decreasing again as the sun goes down. I should have fed in LOADS the last three weeks but no - this install is not going to pay for itself within 10yrs as originally calculated

This smells like faulty gear to me, or maybe very downlevel firmware and a weird configuration corner case.

I'd get back onto your installer and insist they take responsibility for their work, or at least confirm a fault so you can open a warranty case with Fox for replacement hardware.

Hi Calum thanks for input.

My installer, with whom I have enjoyed a very good relationship other the last coupla years (his firm have done much electrical and building work at my properties), said that any broken kit / warranty issues are for Fox to sort out, and both me and he have open email threads with Fox.

Yesterday things improved somewhat with a smoothly incremental rise in PV generation until midday, peaking at 4.5KW. But I don't believe everything is quite right, as by 5PM we were only generating 500W in perfect conditions vs 1.6KW same time last month. I will keep this thread posted

said that any broken kit / warranty issues are for Fox to sort out,

Well, your installer is wrong and you have some pretty cast iron legal rights which you may wish to remind them of.

The installer’s MCS certification can also be revoked.

https://advice.consumercouncil.org.uk/c ... ying-goods

Your installer supplied the goods to you, they are legally responsible for them in the eyes of the law (even if they themselves might go to straight to Fox for redress).