2 Growatt SPF 5000 ES in parallel using 20 550W panels and 1 LifePO4 51.2V 200ah battery

[Supervstech]

Wow, thanks for the details! would love to see a photo of that beast of a battery bank once you're done hooking it up.

Notice the following:
your VOC (uncorrected) = 398.4V
your VOC (corrected for lowest temp) = 415.13V


your Voltage in your graph = 319.7V & 324.2V................................................Far Far from both "corrected & uncorrected VOC" because IT IS NOT VOC! simple!

I know you're probably not convinced, just thought of putting it out for you & from your own post, not mine.

Sure... the voltage in his graph is for yesterday... something tells me it is above 25C where he is right now.

 

[fromport]

Sure... the voltage in his graph is for yesterday... something tells me it is above 25C where he is right now.

It is, and for fun I also calculated the minimum voltage of one of my strings under real warm conditions: 40C/104F


Live and learn.

 

[bgflyguy]

Fwiw, the 5000es manual refers to Voc.

Open circuit Voltage (Voc) of the PV modules not exceeds max. PV array open circuit Voltage of inverter.

Which is 450Vdc

Where the PV Array MPPT Voltage Range is 120Vdc-430Vdc

 

[BeirutSolar]

It is, and for fun I also calculated the minimum voltage of one of my strings under real warm conditions: 40C/104F
View attachment 101902

Live and learn.

there you have it........the wonders of Vmp!
convinced now?

 

[BeirutSolar]

Sure... the voltage in his graph is for yesterday... something tells me it is above 25C where he is right now.

Of course he is, and in anticipation of such answers, i mentioned both corrected (-20C) & uncorrected (STC, i.e. 25C), to both of which my answer stands! (............Far, far from VOC!)

 

[BeirutSolar]

Fwiw, the 5000es manual refers to Voc.

Open circuit Voltage (Voc) of the PV modules not exceeds max. PV array open circuit Voltage of inverter.

Which is 450Vdc

Where the PV Array MPPT Voltage Range is 120Vdc-430Vdc

hence the discussion.

 

[fromport]

there you have it........the wonders of Vmp!
convinced now?

I have to learn to control how to response but this is my best try:
In my location it is currently warmer than 25C so my Voc & Vmpp is lower than the STC values.
I also lost many trees because of really low temperatures in the winter ( -10C/14F).
Only under those conditions the voltage of the panels will go a considerable amount above Voc on the label (specified at 25C)
I will stop responding in this thread since nobody seems to be able to reach you with arguments.
Best of luck with your setup.

 

[bgflyguy]

hence the discussion.

Are you suggesting the 5000es can sustain Vmp up to 450v regardless of Voc rating?

 

[BeirutSolar]

Are you suggesting the 5000es can sustain Vmp up to 450v regardless of Voc rating?

No i am not

 

[Supervstech]

there you have it........the wonders of Vmp!
convinced now?

Of course he is, and in anticipation of such answers, i mentioned both corrected (-20C) & uncorrected (STC, i.e. 25C), to both of which my answer stands! (............Far, far from VOC!)

hence the discussion.

No i am not

This isn’t a discussion… this is someone on the internet posting opinion and misunderstanding the facts. When several superior technical responses are posted and dismissed.

Please sir. Realize you are incorrect. Realize the overwhelming bank of knowledge on this forum just MIGHT understand things better than you believe, and try, please try to let it sink in that you may have gaps in your understanding that could benefit from reading and learning from the members here.

Vmp is a maximum voltage under loaded conditions.

VOC is the unloaded voltage potential at STC of 25C

Both number will change based on temp. High temps result in LOW VOC/VMP low temps result in HIGH VOC/VMP.

VMP is irrelevant under many situations. Such as between MPPT cycles, before and after load buildup, and when equipment is broken, needing service, or being serviced…

Under these situations, VOC and the temperature coefficient calculated offset are critical.

 

[timselectric]

I gave up. I'm too old to bang my head against walls. lol

 

[BeirutSolar]

I gave up. I'm too old to bang my head against walls. lol

lol

 

[Stuartholmau]

Solar panels don't push current to the SCC. The SCC draws what it needs from them. The panels only make it available to the SCC. The only time that I could see damage occurring to the SCC would be from short circuit current surge.

Example:
If one string develops a short, and the other strings are providing their short circuit current to that string.
Then, that string opens the path. (A cell burns through from the overload) at the moment the circuit opened, the short circuit current would be sent to the SCC. It may not be able to clip the current fast enough, before damage could occur.

I have planned for this situation in my system, and recommend that everyone does this also. As long as the short circuit current is below the threshold, it should not be a problem.

...............In my opinion. ................

To avoid short circuit current surge it is advisable to add diode protection to each string of panels. This protects attached panels and equipment being affected by a large current surge generated by a short circuit panel or string. It also reduces the chance of panel fires.

I had a panel develop a short circuit within a segment. It did not combust but the evidence of very high temperatures was present. Most importantly the entitre solar system continued to function normally and no damage occurred to any external devices or subsystems. It was a little piece of advice that was given to me and at $4 a diode, it was money well spent. Then only down side is that it may reduce your programmed maximum charging current to the ambient current specificationof your diode. A small price to pay.

 

[timselectric]

To avoid short circuit current surge it is advisable to add diode protection to each string of panels. This protects attached panels and equipment being affected by a large current surge generated by a short circuit panel or string. It also reduces the chance of panel fires.

I had a panel develop a short circuit within a segment. It did not combust but the evidence of very high temperatures was present. Most importantly the entitre solar system continued to function normally and no damage occurred to any external devices or subsystems. It was a little piece of advice that was given to me and at $4 a diode, it was money well spent. Then only down side is that it may reduce your programmed maximum charging current to the ambient current specificationof your diode. A small price to pay.

Yes, a diode would provide some protection in this situation. I hadn't actually thought of using one for this purpose. That's a good idea.

 

[RayJacob]

Just for interest i run 12 x 545W JA Mono 144 cell on my Growatt SPF 5000 Es
6 and 6 NO PROBLEMS WHATSOEVER ...6 MONTHS NOW

 

[upnorthandpersonal]

Just for interest i run 12 x 545W JA Mono 144 cell on my Growatt SPF 5000 Es
6 and 6 NO PROBLEMS WHATSOEVER ...6 MONTHS NOW

- Growatt SPF 5000 ES has a PV input voltage of max. 450VDC
- 6x545W JA Mono 144 cells string voltage open circuit: 300V

The Voc temperature coefficient of those panels is at -0.275%, so even at -40C you will see a Voc of max. 354V - well within what the Growatt handles.

I wouldn't expect any issues either.