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

[BeirutSolar]

Thanks BeirutSolar, yes i changed to 20 panels 470W and increased battery to 15kwh. I still have more than i use during peak hours but it is better than original configuration.
Also my area has fog on many summer days between 1-5pm so i am guessing i will max at 40kwh/day.

I'm glad to hear you've upgraded your capacity bank as of now. 15kWh is a great start, i guess you know over the course of a few months how it goes, and pick it up from there.
On a side note, may i know where is this installation located? i ask because i'm curious about the fog in the afternoon, is it an island of some sort?
i would almost guarantee your array can deliver 50-65kWh on normal sunny days had i not known your fact above, hence my question about the location.

 

[Jim Lee]

Thanks Ruburnel.
If you look at manual for SPF 5000 ES , it states Max PV input current is 22A

Where did you get Growatt SPF 5000 ES inverters with 22 amp max. Mine purchased 2/2022 from Signature solar max at 18 amps. ???

 

[timselectric]

Where did you get Growatt SPF 5000 ES inverters with 22 amp max. Mine purchased 2/2022 from Signature solar max at 18 amps. ???

The manual does say 22a. But, i believe that is short circuit current. Mine maxes out at 18.2a, and everything above that is clipped.

 

[kuranaga]

your Voc depends on temperature! the Voc on the panel plate is for STC! It can be up to 15% higher at very cold temperatures, so do your calculation correctly!

 

[BeirutSolar]

The manual does say 22a. But, i believe that is short circuit current. Mine maxes out at 18.2a, and everything above that is clipped

Where did you get Growatt SPF 5000 ES inverters with 22 amp max. Mine purchased 2/2022 from Signature solar max at 18 amps. ???

you're both right & wrong. the SPF5000ES on the old firmware maxes out at 18Amps, hence the catalogue stated 18A as max input PV current. However, the updated firmware handles well into the 22A, & so does the updated manual. there is a previous thread which discussed precisely this, and many users debated this exact issue, & concluded what i stated above.

 

[BeirutSolar]

your Voc depends on temperature! the Voc on the panel plate is for STC! It can be up to 15% higher at very cold temperatures, so do your calculation correctly!

VOC is indeed @STC, however when plugged into the inverter this is no longer considered VOC, and generally 15% upwards doesn't do much difference if the installation is within manual specifications. I'll give you an example: my 8 panels read 46V VOC @STC yet add up to 45V once connected. Albeit you are spot on regarding "doing the calculations correctly"

 

[Supervstech]

VOC is indeed @STC, however when plugged into the inverter this is no longer considered VOC, and generally 15% upwards doesn't do much difference if the installation is within manual specifications. I'll give you an example: my 8 panels read 46V VOC @STC yet add up to 45V once connected. Albeit you are spot on regarding "doing the calculations correctly"

Please explain this.
As I understand it, the VOC only drops when not open circuit. So, when charging of course, you won’t get VOC voltage. But the panels easily output VOC and above, Like when the cold sunlight first hits the panels, and the tracker hasn’t begun charging.

 

[BeirutSolar]

Please explain this.
As I understand it, the VOC only drops when not open circuit. So, when charging of course, you won’t get VOC voltage. But the panels easily output VOC and above, Like when the cold sunlight first hits the panels, and the tracker hasn’t begun charging.

VOC is "Voltage at open circuit" or simply put "Open-circuit voltage". When not "open circuit" as you described it above, it is no longer called VOC, & MOST DEFINITELY panels DO NOT output anything past their VOC stated on the label! that is guaranteed. if your panels do that, talk to your supplier/installer about it.
pertaining to your other part of the question, at cold sunlight, you would/might get the MAX output (kWp) or close to it, but never exceeding it in Watts. Voltage is determined by no of cells in series (72, 65, etc....) which is constant & labeled on the back of the PV as the summation of all the cells under the term "VOC". VOC therefore is always @STC & always an absolute maximum, given the controlled testing conditions under which STC is labeled versus the un-controlled, arbitrary & non-standard conditions under which your typical installation might exist/operate.

 

[Supervstech]

VOC is "Voltage at open circuit" or simply put "Open-circuit voltage". When not "open circuit" as you described it above, it is no longer called VOC, & MOST DEFINITELY panels DO NOT output anything past their VOC stated on the label! that is guaranteed. if your panels do that, talk to your supplier/installer about it.
pertaining to your other part of the question, at cold sunlight, you would/might get the MAX output (kWp) or close to it, but never exceeding it in Watts. Voltage is determined by no of cells in series (72, 65, etc....) which is constant & labeled on the back of the PV as the summation of all the cells under the term "VOC". VOC therefore is always @STC & always an absolute maximum, given the controlled testing conditions under which STC is labeled versus the un-controlled, arbitrary & non-standard conditions under which your typical installation might exist/operate.

Incorrect…

Panels ALWAYS output higher than VOC when they are below 25C temperature… it is printed on the label. Correction factor calculation for below standard temp.

 

[BeirutSolar]

Incorrect…

Panels ALWAYS output higher than VOC when they are below 25C temperature… it is printed on the label. Correction factor calculation for below standard temp.

Incorrect...
you're answering to a totally different scenario called "VOC".....i.e. when panel is not connected To ANYTHING! just a voltmeter! then, you would take TC into consideration. This is typically during installation or repair, not NORMAL OPERATION.
i'm answering to when the PV is connected (i.e. operational), we don't call this VOC anymore (as i explained above), it's Vmp (also printed on the label), and that is fluctuating depending on irradiance (W/sqm); Vmp is also much much lower than VOC obviously.

On a side note: TC is nearly 0.02 ~0.031%/deg.C .....meaning @ 0 degrees this would be 25X0.03=0.75% which translates for a panel that outputs 38V @ STC to 38.285V................a DELTA of 0.285V...................negligeable

 

[Supervstech]

Ok, but VOC applies until the charge controller pulls watts from the panels. On cold mornings, when the sun just starts shining, the panels will put out above VOC to the controller and can fry the circuitry.
Vmp voltage implies a LOAD… and shows maximum voltage when loaded.

The VOC multiplier is critical to understand under cold morning conditions.

 

[BeirutSolar]

Ok, but VOC applies until the charge controller pulls watts from the panels. On cold mornings, when the sun just starts shining, the panels will put out above VOC to the controller and can fry the circuitry.
Vmp voltage implies a LOAD… and shows maximum voltage when loaded.

The VOC multiplier is critical to understand under cold morning conditions.

Noted.
i have almost 1 year data from my installation in Lebanon with 10 Trina Panels whose VOC is 49V (TOTAL OF 490v VOC) well beyond the 450V limitation of Growatt's SPF5000ES' VOC. I have not had a single instance of OV fault registered, EVER! & that installation is on a 900m high mountain with winters reaching -1 degrees.

if you would like, i could create a view only user for you to connect to my inverter & see for yourself (Pm me)

 

[timselectric]

I had one too many panels in my strings, on my SPF-5000-ES. And last winter it pushed my buss voltage to high, and shut down the inverter. VOC is checked periodically by the SCC. This is when it will get you. Also early morning, and late evening.

 

[timselectric]

you're both right & wrong. the SPF5000ES on the old firmware maxes out at 18Amps, hence the catalogue stated 18A as max input PV current. However, the updated firmware handles well into the 22A, & so does the updated manual. there is a previous thread which discussed precisely this, and many users debated this exact issue, & concluded what i stated above.

Thanks for the info, I'm going to have to look into this. As I will be adding more inverters to my system.

 

[BeirutSolar]

I had one too many panels in my strings, on my SPF-5000-ES. And last winter it pushed my buss voltage to high, and shut down the inverter. VOC is checked periodically by the SCC. This is when it will get you. Also early morning, and late evening.

can you share some details such as no of panels, strings, PV's VOC's, etc...?

On a side note, i probably forgot to mention, the installation i referred to previously runs 24/7 & is built with Tubular lead acids, so in a nutshell, a load is ALWAYS present as the lead acid constantly draws a couple of hundred watts even when full (float), and the essential load (fridge, freezer, router, UPS, etc....) are always on including the early morning & late evenings...............this could be why i haven't faced any OV faults ?

 

[timselectric]

When the issue occurred.
11s2p 250w panels
VOC 37.6v
SCC max VOC 450v
Very cold and sunny day. Bus voltage went to 500v.
Tripped 3 times on one day, and a few days later.

 

[BeirutSolar]

When the issue occurred.
11s2p 250w panels
VOC 37.6v
SCC max VOC 450v
Very cold and sunny day. Bus voltage went to 500v.
Tripped 3 times on one day, and a few days later.

11 X 37.6= 413.6V @STC to 500 is a delta of 86.V (assuming your panels have a TC of -0.3%V/degree-->for 11S: 1.25V/degree) 86.4/0.125= -69.6 degrees Centigrade.............does that make sense to you?

 

[Supervstech]

11 X 37.6= 413.6V @STC to 500 is a delta of 86.V (assuming your panels have a TC of -0.03%V/degree-->for 11S: 0.125V/degree) 86.4/0.125= -696 degrees Centigrade.............does that make sense to you?

Your math is off…
The panels need only hit -45C to exceed 500V

 

[BeirutSolar]

Your math is off…
The panels need only hit -45C to exceed 500V

you're right, my math was off by a decimal! sorry for that, i fixed it, final figure is Delta T of 69.6 (which translates to roughly -44.6 degrees after redacting the 25 STC).......
Still,
1) Do you get to -45 where you live?


2) Even if you did get to -45, you still haven't tackled the part related to WHY would the SCC would see it as a OPEN-CIRCUIT? is it a separate charge controller without inverter? is there no constant load on inverter? is it not an all-in-one inverter with SCC, MPPT, inverter, AC-DC charger? they way i see it, you should almost never have Zero load, the inverter alone consumes anywhere between 50 to 70 Watts, a baseline load (fridge, router, mobile charger, etc...) would constitute at least 250 ~300W on top of the inverter consumption at idle.....

 

[Jim Lee]

you're both right & wrong. the SPF5000ES on the old firmware maxes out at 18Amps, hence the catalogue stated 18A as max input PV current. However, the updated firmware handles well into the 22A, & so does the updated manual. there is a previous thread which discussed precisely this, and many users debated this exact issue, & concluded what i stated above.

Where is the thread that addresses this. I would like to read it. This week I updated both CPU's on my 4 Growatt SPF 5000 ES inverters to versions 040 06 C.01 for CPU1 and 041 06 C.01 for CPU2. I believe these are the latest versions available. My inverters so far have been maxing at 18.2 Amps. I will continue to watch them to see if that changes. The reason I updated was 3 of my 4 inverters would not start up with battery and PV power. The inverters have to be turned on to power up. At first only 1 inverter had this problem and after about 3 weeks of use 3 of my 4 inverters developed this problem. The update didn't fix the problem. I'm working closely with Signature Solar to try and resolve this problem. If anyone has a theory on what is wrong or what part might be burnt out on the inverters to cause this I would like to hear it.