Overpaneling on SPF5000ES ?

[SPF_Energy]

Situation:

Currently there are 9pcs of JAM60S20 running as string on SPF5000ES.

Short circuit current of these panels is 11.5 amps.

I’d like to add 2nd string (also 9pcs in series) or even a 3rd string in parallel to it just to get more solar power in case of cloudy weather condition. These added strings will consist of same panel type and matched series voltage to the existing.

The spec of SPF5000ES says 18A (22A) max. solar input. Means the inverter will draw no additional current out of the setup. That’s for sure.

My question:

Could there be any risk to the SPF if the whole setup is connected ? (e.g. 3 strings in parallel, as described above means almost 34 amps short circuit current)

Reason for asking: Some competitors inverter specify max. short circuit current. As far as I understand the reason for this requirement is, that they perform some cabling check by short term short circuiting the connected solar panels. As consequence overpaneling is forbidden because the Isc overcurrent would lead to HW damage…

Thanks for help and best wishes from germany,
Thomas

[amos]

Dear Thomas,

Sorry for the late reply because of Chinese Spring Festival!

For SPF 5000ES, your PV system needs to meet the requirement below:
MAX PV input voltage : 450V
MAX PV input current 18(22A, Newest firmware), if you connect more PV strings and PV input voltage doesn’t exceed 450V, even though your PV input current has exceeded 22A( Newest firmware), you don’t need to worry about that will damage inverter. SPF 5000ES will limit PV input current automatically based on MPPT algorithm.

What if you connect more PV strings, excess energy will be wasted.

[SPF_Energy]

Dear Amos,
I hope you had a nice Chinese Spring Festival.

This is really good news !
I’ll upgrade to 9S3P on each SPF. And yes, this configuration won’t exceed 450V even below -20°C.

But should I add external melting fuse for safety to cut off in rare case of internal FET break down ?
Just to prevent layout current overload in this failure mode.
What do you think ?

Best regards,
Thomas

[[email protected]]

Hi , where i can find the update and how i can installed , can work with all version of spf5000es series
Thank you

[amos]

Really sorry for the late reply!

1.”I’ll upgrade to 9S3P on each SPF. And yes, this configuration won’t exceed 450V even below -20°C.”

What do you mean by “I’ll upgrade to 9S3P on each SPF”,

2. “should I add external melting fuse for safety to cut off in rare case of internal FET break down ?
Just to prevent layout current overload in this failure mode.”

For off grid inverter, there are so many mosfets inside inverter, especially DC-DC circuit, you can try to add the melting fuse on AC output and observe if it will descrease the malfunction. What if it really works, please kindly let me know.

[amos]

what do you mean? Firmware upgrade?

[kirkdis]

amakki, how do you setup your 9S3P configuration? if you have three strings and fuse each of them seperately this should be the best way in my opinion. So in a case of malfunction in one string the fuse will brake down. What I did I added 3 cut off switches so I can activate or deactivate each string separately for maintenance reasons.

[SPF_Energy]

Hi Amos,

thanks so much for your support !

1. > What do you mean by “I’ll upgrade to 9S3P on each SPF”

It’s not about FW upgrade.

I just meant to add / upgrade a 2nd and 3rd string – 9 panels each – in parallel to existing 9 panels in series as I’ve already described above.
“Upgrade” from current 9 to 27 panels in total on each inverter.
Voltage is then 9x of a single panel
But max. current will be 3x ! (Short circuit current of course)

As far as I know the solar input of the SPF5000 consists of a boost circuit and it is designed for 18 (22) amps.
So in normal condition there should be never higher currents. Managed by the firmware.

But in case of the low side FET breakdown of the internal boost circuit of the SPF5000 there could be 3x Isc = 34 amps !
So I’d place one melting fuse ~25A on the solar input.

kirkdis33:
Of course each “9S” string will get it’s additional separate fuse mainly intended as breaker for service. ~16 amps each fuse. (The panel is allowed for 20A)

[kirkdis]

overpanelling is fine with those inverters as stated before. I have a 10S2P connected to one inverter. the SPF are not really efficient here in summer but in low light conditions or especially in winter you will have a lot of advantages from the mppt regulator…

[[email protected]]

Dear Amos

I have two SPF500ES. Both were purchased in 2022.
They have different software. Is this suitable for MAX PV input current 22A?
1.
CPU1: 067 00 6.24
CPU2: 068 00 6.24
2.
CPU1: 067 01 1.04
CPU2: 068 01 1.04

Thank you.
Božo

[Author]

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