FoxESS Community - Owners & Installers Forum

Today's question from the "Why did it do that?" member.

My installation comprises 12 Hengdian 450 PV panels, Fox inverter and Fox IP12 battery.

Yesterday, after the initially cloudy start with intermittent gaps of brilliant sunshine it finally settled down to a brilliantly sunny afternoon. So I would have expected the output to rise up to near, if not in excess, of the near 5kW levels I had seen previously during brilliantly sunny gaps between the clouds - one short period got up to 5.63kW!.

It looked like it was going to flatline today but instead just peaked at around 4.25kW and no higher.

Please see attached images.

So why the flatline from just after 12 noon to around 14:22?

Any clue as to why?

Am I expecting too much?

Best regards,

Derrick.

Do you know what your system Export limits are?
If you say have 4kW limit, then unless your battery has room to mop up the power, the PV will reduce output.
If you was getting to an export limit, then you would see a plateau on your PV graph if battery is full.


The other thing to mention is "cloud edge affect" where the Sun can peek around the edge of a cloud and you see some big spikes above your typical values.

Hi, thanks for the reply.

The export limit is 5kW set by the NDO when the approval was granted - that's why I was puzzled by the flatline.

I did initially think that maybe it was the very slightly hazy sky but to my thinking all that would have done is limited the maximum and not resulted in a flatline.

Oddly enough, today there was no haze that I could perceive and yet, while there was no flatline, the maximum was lower.

It's a learning curve.

Best regards,

Derrick.

Ok so the DNO limit is fine at 5kW.
To my eyes I wouldn't say you had a flat line, the curve is a little flatter but not what I would worry about.

As for spikes, as mentioned the edge affect most likely.
Panels also are not fans of heat, so you get nice power when it peeks around a cloud, and the heat drops the efficiency and flattens things out.

In Spring/Autumn you will get nice good days as the panels are not yet really cooking, and in Summer the output will be higher, but not as always expected on extremely warm days.