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

[carpediem80]

I have the following components and i would appreciate your feedback on best configuration for my panels:

- 2 Growatt SPF 5000 ES (europe and will use it at 240V)
- 20 550W panels
- Voc = 50.32V STC and 48.1V NOCT
- Isc = 13.92A STC and 11.07A NOCT
- Vmpp = 42.28V STC and 39.9V NOCT
- Impp = 13.01A STC and 10.45A NOCT
- Max series fuse rating 25A
- Temperature coefficient for Voc is -0.28%/deg C
- Temperature coefficient for Isc is +0.05%/deg C

- 1 LifePO4 51.2 V 200ah battery

- If i use 10s on each inverter then i exceed Voc max of inverter ( 503.2V vs 450V)
- if i use 5s2p on each inverter then Isc reaches 27.84A

Growatt SPF 5000 ES has max PV input current at 22A.

Should i just ignore 2 panels and use
8s on each inverter?

Many thanks for all your help

 

[Ruburnel]

I stand to be corrected, but I don't think you have any choice but to "lose" two of the PVs from each string as you've exceeded the capacity limits of the Inverters

I guess you could also go 9s to give a total VoC of 452.88 which is only just over the stated 450v of the Inverter?

A quick look on the Internet suggests that the maximum MPPT current is actually 100A for the SPF 5000 ES:

 

[timselectric]

It's ok to overpanel on watts and amps. 25% over is standard practice. This helps on cloudy days.
But, do not go over the rated VOC. (Corrected for temperature) this will damage equipment.

5s2p is the way to go with what you have.

 

[Supervstech]

For me, I'd go 8S, and get 6 more panels...

 

[carpediem80]

I stand to be corrected, but I don't think you have any choice but to "lose" two of the PVs from each string as you've exceeded the capacity limits of the Inverters

I guess you could also go 9s to give a total VoC of 452.88 which is only just over the stated 450v of the Inverter?

A quick look on the Internet suggests that the maximum MPPT current is actually 100A for the SPF 5000 ES:

View attachment 95025

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

 

[Ruburnel]

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

I thought I might be corrected

 

[carpediem80]

It's ok to overpanel on watts and amps. 25% over is standard practice. This helps on cloudy days.
But, do not go over the rated VOC. (Corrected for temperature) this will damage equipment.

5s2p is the way to go with what you have.

Thanks Timselectric.

So max for 5s2p will be ~ 251.6V and 27.84A or 7000W.
The Max PV input power for this inverter is 6000W.
What you are saying is that the inverter will simply clip how much it draws from the panels to stay below 6000W?

So 5s2p for each inverter is safe, right?

 

[carpediem80]

For me, I'd go 8S, and get 6 more panels...

Thanks Supervstech.
I am not sure if i got what you mean.
if i go 8s for each of the 2 inverter then i have 4 extra panels. You mean i should add 4 more panels to make it a 3rd set of 8 on a 3rd parallel inverter?

 

[timselectric]

Thanks Timselectric.

So max for 5s2p will be ~ 251.6V and 27.84A or 7000W.
The Max PV input power for this inverter is 6000W.
What you are saying is that the inverter will simply clip how much it draws from the panels to stay below 6000W?

So 5s2p for each inverter is safe, right?

Correct, on all.

 

[carpediem80]

Correct, on all.

Thanks.
I think that way will be also more efficient for charging the batteries, right?
5s2p: 250V DC to 48V DC.
vs.
8s: 400V DC to 48V DC

 

[timselectric]

Generally, higher PV voltage is preferred for efficiency.
But as long as you are in the functioning range, the SCC will work it out.

 

[timselectric]

I have the SPF-5000-ES. And have found the sweet spot for PV to be 333v & 18a.

 

[BeirutSolar]

I have the SPF-5000-ES. And have found the sweet spot for PV to be 333v & 18a.

you're spot on @timselectric !

 

[BeirutSolar]

I thought I might be corrected

what you highlighted (100A) is the max DC charger current OUTPUT, while what @carpediem80 was referring to is RAW MAX current output from PV strings, 2 very different things.

 

[BeirutSolar]

Thanks Timselectric.

So max for 5s2p will be ~ 251.6V and 27.84A or 7000W.
The Max PV input power for this inverter is 6000W.
What you are saying is that the inverter will simply clip how much it draws from the panels to stay below 6000W?

So 5s2p for each inverter is safe, right?

YES indeed, clipping is a common occurence, in those rare occasions of Super sunny days where your PV strings MIGHT max out for an hour (give or take), but you get the benefit of a wider bell-curve for the rest of the day resulting in a higher kWh energy yield throughout the year. IMHO, a tiny, time-limited drawback for a year-round benefit.

 

[BeirutSolar]

I have the following components and i would appreciate your feedback on best configuration for my panels:

- 2 Growatt SPF 5000 ES (europe and will use it at 240V)
- 20 550W panels
- Voc = 50.32V STC and 48.1V NOCT
- Isc = 13.92A STC and 11.07A NOCT
- Vmpp = 42.28V STC and 39.9V NOCT
- Impp = 13.01A STC and 10.45A NOCT
- Max series fuse rating 25A
- Temperature coefficient for Voc is -0.28%/deg C
- Temperature coefficient for Isc is +0.05%/deg C

- 1 LifePO4 51.2 V 200ah battery

- If i use 10s on each inverter then i exceed Voc max of inverter ( 503.2V vs 450V)
- if i use 5s2p on each inverter then Isc reaches 27.84A

Growatt SPF 5000 ES has max PV input current at 22A.

Should i just ignore 2 panels and use
8s on each inverter?

Many thanks for all your help

i would like to highlight a design handicap in the above that no one has raised in this thread so far. The above PV array is 11KWp, which can yield up to high 50's kWh (or more), while your battery is just a tad shy over 10kWh.
Unless you have heavy loads that might benefit from all that produced energy throughout the day, you're in loss of valuable generated energy.
I would either increase the battery bank capacity to at least 2/3 of daily production or more, depending on where you live, and whether this is an off-grid, on-grid, or in an area where blackouts are common; or decrease the array size. First option being my "go to" plan.

 

[Blackmoses]

It's ok to overpanel on watts and amps. 25% over is standard practice. This helps on cloudy days.
But, do not go over the rated VOC. (Corrected for temperature) this will damage equipment.

5s2p is the way to go with what you have.

I ordered the same model of the inverter and contacted both signature solar and growatt support
because I was thinking of 5s2p for a 540w panels by jinkosolar

Signaturesolar recommends max input amp 22, optimal is 18

growatt support said 27amp would damage the inverter

 

[timselectric]

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. ................

 

[Blackmoses]

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. ................

Hmmmmm
I wish this is true. Can anyone verify this hypothesis? Would be exciting.

 

[carpediem80]

i would like to highlight a design handicap in the above that no one has raised in this thread so far. The above PV array is 11KWp, which can yield up to high 50's kWh (or more), while your battery is just a tad shy over 10kWh.
Unless you have heavy loads that might benefit from all that produced energy throughout the day, you're in loss of valuable generated energy.
I would either increase the battery bank capacity to at least 2/3 of daily production or more, depending on where you live, and whether this is an off-grid, on-grid, or in an area where blackouts are common; or decrease the array size. First option being my "go to" plan.

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.