SolarEdge Guru Needed

[Somedumbhomeowner]

Hi guys. Drama brings me here to inquire about wiring my panels into 3 strings on a SE11400A inverter. But first a little backstory.
So my contractor outsourced the installation of my system who installed 36 Hanwha 295w panels in two strings. 18 on string 1 and 18 on string 2. This apparently exceeds the max watts per string the inverter can handle and of course we find out after the company has replaced the inverter now for a third time and currently waiting for the company to come and "re-string" the panels to all three strings.
So my question is this. Would it be possible to "re-string" my panels with 14-string1/14-string2/8-string3? I ask because I've seen a spec sheet on other Solaredge inverters that state there should not be more that a 1kw difference between strings. I simply want to leave the third string open to add more panels down the road without having to restring everything again.

[ButchDeal]

Yes but it would be a minimum recomended string

[Somedumbhomeowner]

Yes but it would be a minimum recommended string

Thanks! Hopefully there is a way to leave the last string "ready" to accept more panels on a different section of roof.

[Mike90250]

Thanks! Hopefully there is a way to leave the last string "ready" to accept more panels on a different section of roof.

That will only work if the new portion of the string has the same solar orientation as the existing part.

[ButchDeal]

That will only work if the new portion of the string has the same solar orientation as the existing part.

no it is solarEdge, every single PV module can have different orientation.

Sorry, I missed that part, I just saw string. So each panel will still need it's own optimizer.

[ButchDeal]

Thanks! Hopefully there is a way to leave the last string "ready" to accept more panels on a different section of roof.

you would just have to break the connection and add the new modules onto the string. Make sure that you use compatible optimizers as well.

https://www.solaredge.com/sites/default/files/application_note_intercompatibility_se_power_optimizers_na.pdf

[JSchnee21]

I have 37 panels on my 11400A in three strings. 12, 12, 13. But I'm out of roof space for more panels unless I use the North face. Lots of folks talk about adding more panels in the future, but it reality it rarely happens. Most folks that are really serious about it end up adding a second smaller inverter later.

[ButchDeal]

Lots of folks talk about adding more panels in the future, but it reality it rarely happens. Most folks that are really serious about it end up adding a second smaller inverter later.

for most people adding a second inverter is just the simplest option. For SolarEdge customers (and micro inverter customers) there is often a simpler and more efficient option of just installing more pv modules onto the existing system. Degradation of the PV modules over time means that there is inverter capacity, or installing on different azimuths can spread the inverter capacity over longer time frames.

[Somedumbhomeowner]

I found and played with the designer tool last night to recreate my setup and add the future array of additional 6 panels over the garage. It didn't give me any errors so it looks like i shouldn't have any problems. The third string lit up green when I hit the 8 panel minimum and gave no warnings about power discrepancy between the strings. Not sure if designer is smart enough to know that? I guess I can mock up something ridiculous and se what kind of warnings I get.

[Somedumbhomeowner]

Wish my contractor would have used this tool! While playing around with strings I clearly got a warning about exceeding string wattage when attempting to string 18 panels together. No warnings so I think I'm good. Thanks again guys! They are supposed to be coming today to restring.

[Yet another Yeti]

Solar Edge accepts 500 Vdc input , according to the datasheet .

That way , both 18er strings would need to be each split in 9 parallel .

According to some 295W Hanwha Qcells datasheet , the currents range from 7 to 10 amps at NOC and STC ,
but might be lower at low temperatures , and voltages higher .

The voltage range of 9 modules

[Yet another Yeti]

... Next truncation using the multiply special sign on Android 6.0 broweser , preview worked ...


... 9 modules * 50 Volts , but the Amps would be 2*2*10 Amps , and therefore not in the range anymore .
A footnote of the SolarEdge datasheet claims , that the inverter would ignore any Amps about thresholds .

Two 7600er could do the trick , or some device of a higher output series , like the 12k and above .

[ButchDeal]

Solar Edge accepts 500 Vdc input , according to the datasheet .

That way , both 18er strings would need to be each split in 9 parallel .

According to some 295W Hanwha Qcells datasheet , the currents range from 7 to 10 amps at NOC and STC ,
but might be lower at low temperatures , and voltages higher .

The voltage range of 9 modules

You are forgetting about the optimizers with SolarEdge. They are required and have a buck/boost voltage regulator so you do NOT need to consider the DC voltage input of the inverter. In fact you should not consider it at all.

You need to look at the wattage of the strings to stay under the max allowed for the optimizers and keep the strings as long as possible yet under the string max length (usually limited by wattage though with modern PV modules).

[ButchDeal]

... Next truncation using the multiply special sign on Android 6.0 broweser , preview worked ...


... 9 modules * 50 Volts , but the Amps would be 2*2*10 Amps , and therefore not in the range anymore .
A footnote of the SolarEdge datasheet claims , that the inverter would ignore any Amps about thresholds .

Two 7600er could do the trick , or some device of a higher output series , like the 12k and above .

What in the world are you talking about here? OP has an SE11400A which is capable of 11.4kW, plenty for this install.

[Yet another Yeti]

What in the world are you talking about here? OP has an SE11400A which is capable of 11.4kW, plenty for this install.

OK, probably I am able to understand the Solar Edge concept now : SE keeps the voltage constant at 8+ Modules,
but increases the amps , to reach the Wattage , as Power = Voltage * Amps .

But what is this line about :
V @ 350 / 208V @ 325 Voltage Input DC.

When one of the 18er strings delivers some 5 kW , and these 5 kW divided by 240 V constant string voltage , I gain
around 20 Amps , and both strings then would make 40 Amps , too much for the 34 Amps allowed as Adc for the 11400A ...?