Solar Panels being clipped /limited on Inverter Input

[JonesyJT]

The thought of MPPT2 not being connected was a good thought, but just looked at system on a partially sunny day (11am) and both inputs are generating but still being limited to 3.8Kw. I will take another shot later this afternoon when both arrays should be in full sun and see how the numbers have changed

 

[Al D]

What are the specs of your panels?

 

[JonesyJT]

They are 385w panels
Panels both in full sun and maxed out at 3.8kw. I think something in the system is clipping them?

I have also just noticed that soc on graphic is showing 39% but via app it shows that batteries are nearly fully charged , which I would expect by 2:37pm in the afternoon when I have been out and minimum load in the house !!!

 

[JonesyJT]

It looks like the graphic on the inverter had frozen. It’s now ok and shows the 10pv array generating over 3kw whilst the 5 over array is approx 800w - sun is directly on the 10 and to the side of the 5 - but both are dynamicly moving and still being clipped to 3.8kw

 

[Al D]

What are the voltage and current specs of your panels?

 

[100FUEGOS]

Your inverter is clipping at 3.8 kW because it cannot cope with anything more. It can only deal with 3.6 kW (officially) either inverting and / or charging the batteries. There is nothing to fix as nothing is not working as it should here. Your installer is wrong.

robby already mentioned it a few posts before.

 

[wattmatters]

It looks like the graphic on the inverter had frozen. It’s now ok and shows the 10pv array generating over 3kw whilst the 5 over array is approx 800w - sun is directly on the 10 and to the side of the 5 - but both are dynamicly moving and still being clipped to 3.8kwView attachment 107289

The big difference now is the SOC of the battery. 100%.

At 100% it will (should) not accept any more charge, so it's entirely reasonable the PV system is clipping because it's only now servicing the AC side (loads + grid export) to the maximum of its capacity and has no output capacity headroom to send any excess PV capacity on the DC side (since the battery is fully charged).

I also get the feeling from the last few posts that your display monitoring has been not reporting battery SOC correctly and it might have been the case in your earlier examples that your battery was actually fully or nearly fully charged while the display was showing it was not full. Again that would explain the PV output being clipped.

 

[Al D]

I'm not familiar with this device, but I do know that the 3.6kW rating everyone keeps citing is really the AC output. It doesn't necessarily represent the total power capacity of the unit. In fact, this model has a max DC input of 4680W. It would be very odd for a unit to accept 4.7kW in, but only use 3.6kW (or 3.8kW as is the current theory) of it. I posit that there is a configuration which allows all 4.7kW to be used under certain conditions; charging the battery and supplying household power.

From the last few pictures of the MPPT power for both strings, it appears there is something stopping full power generation from each string. It is likely not a coincidence that the total power accepted by the unit is 3.8kW, but I don't think it is because this is a "3.6kW" unit. Batteries aren't charged with AC power, which is what that 3.6kW represents.

I wonder what would happen if string 2 was disconnected.

OP, is there any indication what string 1 and string 2 inputs go to specifically?

 

[wattmatters]

It would be very odd for a unit to accept 4.7kW in, but only use 3.6kW (or 3.8kW as is the current theory) of it

No, that's very normal for grid tied inverters. Most are rated to be connected to a PV array with up to ~ 150% of their rated AC output. They are designed to clip PV production when the maximum output capacity of the inverter is reached.

My Fronius inverter is 10 kW AC output but I can (technically) connect up to 15 kW of PV to it and be within specifications for the inverter. If you do that the idea is generally to have arrays facing different orientations so the peak output is lower than the nameplate capacity of the entire array but is spread over more hours of the day.

It's just some hybrid inverters have a total capacity output consisting of their AC output capacity + the DC output capacity.

 

[wattmatters]

From the last few pictures of the MPPT power for both strings, it appears there is something stopping full power generation from each string. It is likely not a coincidence that the total power accepted by the unit is 3.8kW, but I don't think it is because this is a "3.6kW" unit. Batteries aren't charged with AC power, which is what that 3.6kW represents.

Again, you need to validate the actual specifications of the inverter to identify its total simultaneous combined AC and DC output capacity. I can't access the spec sheet (well I can but I'm not signing up to do it).

 

[Al D]

I didn't realize that about grid tied inverters. I'll remember that if i ever need one. I've attached the datasheet from the website I referenced earlier. No need for signing up. It's not a wiring schematic, but it does indicate max parameters.

 

[wattmatters]

I've attached the datasheet from the website I referenced earlier.

It says nothing about combined AC and DC output capacity though. Perhaps the user manual is more instructive on that?

 

[Mystery Man]

Is this the correct user manual?

 

[JonesyJT]

Hi folks.
Thanks for your comments.
I will dig out the specs for the pv and inverter. The spec posted for the inverter is the wrong one.
There is a setting, as previously posted, that allows you to use Max Solar Power. Mine is set to 6500w which far exceeds my theoretical capacity of 5.77kwp

Wattmatters hit the nail on the head in that if the soc is less than 100% then all available power should be used to charge the batteries and supply the load. Once batteries are fully charged than the pv should be limited to the output capacity.
As far as I can see this is not happening.

Yes it would seem that the graphic was frozen, but previous graphs/data have been obtained through app and web connection so what you saw was correct.

 

[JonesyJT]

Hi there,
the spec of the investor is :-
SUN-3.6K- SG05LP1-EU and have attached the manual with spec included.

the Panels are :-
385W JA Solar with PERC Technology with data sheet attached

As far as I can tell, the Max DC Power (from PVs) is 7000W, and max AC output power is 3.6Kw

TIA

 

[JonesyJT]

My only other thought on this is the setting for Max Solar Power...

It is on a screen with DRM above it, but it isn't ticked/enabled. Not sure if both are linked and wether the DRM has to be enabled for the Max Solar Power to be active. Currently it is set to 6500W which is well above the 5.77Kw max limit of the PVs - see similar screenshot from manual.

Does anyone have any experience of this?

TIA

 

[wattmatters]

I think you are going to have to keep badgering your installer.

 

[JonesyJT]

I think you are going to have to keep badgering your installer.

I’ve had a message from installer that Sunsynk are going to update the inverter with the latest firmware, as there is a bug in my version of the firmware that clips the pv inputs.
This should happen today or tomorrow. Once done and I see evidence that it has worked I will post a screenshot.

 

[djhackett2000]

Hi, I have exactly the same issue!! I have the sunsynk 3.6 hybrid, with a 6.7kw array. 5.12 kwh battery. Just like you, when the battery is low state of charge, in full sun, its clipping at 3800w. Litterally never goes over. Max array set at correct size. 7.2kw mppt. Confused! Its clipping like it should when the battery is full, but doing it even when the battery is empty. Did you get the software update? Did it work?

 

[JonesyJT]

Hi

Hi, I have exactly the same issue!! I have the sunsynk 3.6 hybrid, with a 6.7kw array. 5.12 kwh battery. Just like you, when the battery is low state of charge, in full sun, its clipping at 3800w. Litterally never goes over. Max array set at correct size. 7.2kw mppt. Confused! Its clipping like it should when the battery is full, but doing it even when the battery is empty. Did you get the software update? Did it work?

hi there,
Yes I just got it resolved this week by a firmware/operating system update by Sunsynk. Was promised it a few weeks ago but didn’t happen. Looks like there was a bug in system. Now working fully?
Will post picture of my version so you can compare.
Hope this helps