It is very common for installers to NOT put in the string information thus making it look like many installs have a single string.

Looking at the connections at my SE 3800 HD inverter there are single black and red wires from 19 panels (5700 Watts) on my roof. That is a DC to AC ratio close to the max allowed by SE. Isn't string size criteria more about maximum volts or Amps per string?

Ah! I thought that logical layout was something that the inverter itself created based on scanning panel configuration. So if logical layout is something the installer puts in, then you are probably correct. And that also explains why when I looked at voltage and current data for the panels, things did not add up. Voltages were too high to add up to 380VDC on the string.

With SE it's more about power... which in this case translates to amps (15A). With non-optimized string systems the limit is voltage (600v).

Look at the optimizer output voltage vs. realtime string voltage. Then divide string voltage by optimizer output voltage. That will tell you how many panels are actually in the string.

The optimizers do not all put out the same voltage in a string.

Very close to it though.

Depends on how the panels are oriented. If they're all receiving the ~same amount of sun... yes. I have a SE system with SE and SW panels. In the morning the optimizer voltage on the SE panels will be higher than the voltage on the SW panels because the power on the SE panels is higher. So I could have a SE panel producing 270w and the optimizer voltage is 30v and a SE panel producing 150w with the optimizer voltage at 17v.

In a non-optimized system voltage is based on temperature and current is based on power (light). The SE optimizers kinda flips the script making VOLTAGE the variable that changes with power since current must be equal at all points in a series circuit. The total series voltage is maintained at ~350v but individual optimizer voltage will change depending on the power output of that panel. If the power output is the ~same then the optimizer voltage will also be the same.

Actually, while @nwdiver and @Butchdeal are correct of course, I still used the idea @Ben25 raised and determined that yes, the strings that were listed as being one single string were indeed 2 or sometimes even 3.

Looking at the charts section (there were a few public sites that had this level of access), I selected all optimizers and did an Opt Voltage graph. I looked for a time of day where everything was stable and in a tight line. I then looked at the voltage to see if it was 380/x for x panels. It was typically 2x too high, indicating 2 strings.

So you cannot reliably just click on 'info' on a panel, but rather do a full chart over time and find times of settled behavior to analyze.

But more to the point, I never found any SE5000H with more than 5700 in a single string, even though there were many, many listed that way in their site setup. As @Butchdeal says, there are a lot of installers that were a bit to lazy to correctly list the string info.

And, I did hear back from SE that indeed while the SE5000H will never allow more than about 5000W anyway, installers must still avoid strings over 5700W on that inverter. I guess making the exception for over 5700W in a string for the SE5000 and below would add some confusion.

actually no they are not. why would you expect them to be. The amperage is fixed so any shadow is going to have the voltages fluctuate from optimizer to optimizer...

Sorry, I just picked one of my 300 sites and looked at voltages... I guess I'll pick a different one next time...

I just picked one at random with some shadows and graphed optimizer voltage...
You can see how the others have to go up a bit as one goes down..
Charts.jpg

Old thread, but I thought I would update with new information. I have been trying to convince SolarEdge for several years to allow single string more than 5700W DC to be used on SE5000 since the inverter will never allow more than 5000W output anyway. It appears the logic finally won. They now allow you to put any combination of up to 25 panels on a SE5000, even it if puts you above the 5700W limit. Just FYI.