question

CCB avatar image

PV throttling very often

I have recently installed an ESS System (Victron Multiplus 48/5000/70) with one BYD 5kWh and Fronius PV Inverter connected on AC out (on-grid system).

ESS is on "Optimized (Without BatteryLife)". The connection between PV Inverter and Victron is wireless.

The system is working ok but I have some issues which for the moment are unsolved.

For example, the PV production is frequently stopped just to return in the next seconds.

As you can see from the graph, PV is having a strange behaviour when charging the batteries, the graph looks like a saw teeth when I was thinking to be like a smooth line. The PV throttles down to 0 frequently as you can see and I do not know the cause of this.

Any ideas?

BYDFronius
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02.jpg (45.9 KiB)
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Nobody can look at this and give me some hints?? @Guy Stewart (Victron Community Manager) @BYD_service ?

Hi @CCB

You're not giving much information to go by here, so I have to assume some things, please correct me if wrong:

-you have a zero feed-in system?

-you also have AC users?


Please also provide the graph for the AC use, usually fluctuations in used power result in these 'gaps' because the system has to stabilize when loads turn on/off.

CCB avatar image CCB Daniël Boekel (Victron Energy Staff) ♦♦ ·

I have posted my reply to you as a answer by mistake, I am new to this form and not really know how to use it.

Hi Daniël, thanks for your reply and apologise for not giving more info.

Your assumptions are correct, is a zero feed-in system with users connected to AC.
I have attached also the graph with AC use from the same day.

In the first attached graph, the BYD battery is charging until around 13.30hrs so after thet, the behaviour of PV system is normal, delivering only when there is a demand.
My question is why I still have PV production drops from 2700W down to 0 when there are no big changes in consumption/demand.


Last graph is fron today.

Name of the installation is Casa cu Brazi - Stefanesti and VRM portal ID is 9c1d58390769 if it helps.

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Hi @CCB

The Fronius gives some errors, I'd first look into the communication between Fronius and GX device.

Maybe you can log into the Fronius to see if there are errors stored, it seems the dips don't have anything to do with the Victron system.


CCB avatar image CCB Daniël Boekel (Victron Energy Staff) ♦♦ ·

Thanks Daniël, I will look into it.

Fronius and GX Device are connected by wireless, I will try to connect by cable to see if there is any improvement.

Unfortunately, I can do this only after 2 weeks because I am not at the location now.
I will keep you informed.

Thanks again!

Ok perfect.

Wireless is always tricky, lot's of potential disturbances around.

2 Answers
Justin Cook - Bay Marine Supply USA avatar image
Justin Cook - Bay Marine Supply USA answered ·

@CCB, though I am not an expert in the Fronius or BYD devices, this looks to me like what I would expect to see if one of the connections was bad on the PV side... I've seen very similar graphs in systems where there was a bad MC4 connection that would overheat under load, causing the controller to throttle, which would allow the MC4 to return to normal temperature, then the controller would apply load again, causing the MC4 to overheat again, etc.

This applies both to the actual MC4 connectors as well as to any crimps/fuses/breakers etc... It may well be something more complex elsewhere in the system, but this is a relatively simple place to start. If you have a thermal IR camera or a non-contact thermal sensor, it's relatively easy to go through the system on the PV side and look for an unusually hot connector somewhere along the line.

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Thank you for mentioning this, I need to check this also. Fortunately, one of my neighbor has a Flir camera so I can borrow it and check for bad connections.

I will keep you informed.

BYD_service avatar image
BYD_service answered ·

Hello @CCB,


Can you plot the CCL next to the PV generation? This would tell us if generation is curtailed by the battery (If CCL goes to 0 at that time) or it's something else.

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Hello BYD_service,

I hope that i have attached the correct one (this is from today):

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