Hi Guys ,

I recently the new bought 8 JA Bi-Facials, Deep Blue 4.

They have been running in 7 in series and 1 in parallel on a single string.

The Inverter is a Sunsynk 8kw. - I have another array on the other string. (Completely different panels etc)

One of them was damaged during installation and cracked.

The installer did swap it out however it's not identical.

My current panels are JAM66D45-660/LB

Voc 47.70V

Vmp 39.44V

Isc 15.95 A

Imp 15.21 A

The replacement is JAM72D40-600/LB

Voc 52.40V

Vmp 43.76V

Isc 14.48 A

Imp 13.71 A

I am concerned with that this is not the same specs. I don't want to have my system restricted or not running as efficiently as possible.

Also with this one panel being different could it cause any reliability longer term ?

I'm not sure what you mean by 7 in series and 1 in parallel on one input. I would expect all 8 of these panels in electrically in series on one input.

The replacement panel has got a lower peak current, ie. 13.71A instead of 15.21A. That means that at peak production you are likely to restrict your maximum output, by a reduction of just under 10%. Most of the year probably not critical, but in summer you will be generating somewhat less at mid-day. If at all possible I'd try to stick to a panel with closer specs, but if you've got enough power overall to meet your needs, it might not be critical. Just a personal 2c. Others can comment better maybe on this, and on reliability.

2 hours ago, GreenFields said:

I'm not sure what you mean by 7 in series and 1 in parallel on one input. I would expect all 8 of these panels in electrically in series on one input.

The replacement panel has got a lower peak current, ie. 13.71A instead of 15.21A. That means that at peak production you are likely to restrict your maximum output, by a reduction of just under 10%. Most of the year probably not critical, but in summer you will be generating somewhat less at mid-day. If at all possible I'd try to stick to a panel with closer specs, but if you've got enough power overall to meet your needs, it might not be critical. Just a personal 2c. Others can comment better maybe on this, and on reliability.

Hi There.

So on one of my strings. I have 7 panels running in series.

Then I have a single panel that is running in parallel to those.

del

Edited April 12, 20251 yr by GreenFields
Post self-deleted. Crossed lines.

4 hours ago, Dry_Reef said:

Hi There.

So on one of my strings. I have 7 panels running in series.

Then I have a single panel that is running in parallel to those.

In a string, voltage adds, and current is limited by the lowest panel in the string. When you add a parallel panel, it tries to inject more current, but the MPPT can’t track two different currents at two voltages efficiently ,it ends up tracking the lowest common denominator, hurting efficiency. The single panel will be heavily underutilized, and might even drag the string’s performance down a bit due to instability in MPPT tracking.

When you do something unusual like this, you can get erratic tracking, reduced power, or weird behavior like hunting (oscillating Vmp)

Having one panel in parallel to a string of 7 in series is highly peculiar. Where you have one panel out of spec, you want it rated at higher current than the rest. I suggest moving the odd panel to the old array or adding a power optimiser to use it with the 7 new panels.

17 hours ago, Dry_Reef said:

They have been running in 7 in series and 1 in parallel on a single string.

if 7 panels are in series and one more (the replacement) is in parallel with the 7, then it won't do anything for you, so disconnect the 8th/replacement panel... and read further...

17 hours ago, Dry_Reef said:

My current panels are JAM66D45-660/LB

that is 66 cells in the panel...

17 hours ago, Dry_Reef said:

The replacement is JAM72D40-600/LB

that is 72 cells in the panels, which is not a total train smash, however the Imp of this panel should be within, let's say, 0.5A of the 66 cell panels for this to work in series with the other 7, it would bring up the Voltage of the 8 panel string by a bit more, than if all 8 panels were 66 cell panels, but I'm sure you would still be within your Voltage limits on the MPPT input.

So, if you can get the installer to replace the 8th panel with one that is a bit closer to the Isc and Imp figures of the other 7 or even exceeding the Isc and Imp of the other 7, then that would work best and you would hardly notice from a power production point of view, that one panel was different from the rest in the string,