TL on an old system?

[Zee]

Pretty sure i know the answer, but is there any way i could use a SMA TL inverter on an existing system built in 2002?
(The (E) SMA 2500U needs replacement.)
(USE wire, not PV wire used)

Why does Code require PV wire for ungrounded systems and not GFDI fuse protected ones (grounded)?

The way i see it: this inverter has AFCI, gr. fault detection and is the latest. Why the extra requirements in DC conductor insulation?

Code aside, wouldn't it arguably be better than using a grounded, previous model? (e.g. SMA SB4000US)

 

[ggunn]

Pretty sure i know the answer, but is there any way i could use a SMA TL inverter on an existing system built in 2002?
(The (E) SMA 2500U needs replacement.)
(USE wire, not PV wire used)

Why does Code require PV wire for ungrounded systems and not GFDI fuse protected ones (grounded)?

The way i see it: this inverter has AFCI, gr. fault detection and is the latest. Why the extra requirements in DC conductor insulation?

Code aside, wouldn't it arguably be better than using a grounded, previous model? (e.g. SMA SB4000US)

You would have to check the stringing; the operating voltage range for the TL units is narrower than for the standard units. Also, if you have more than 2 strings you will have to add a combiner box which fuses both the positive and negative conductors because the TL units do not have integrated multistring DC discos like the grounded models have.

As for the DC conductors, the code is the code, irrespective of why it says what it does.

 

[Zee]

good point on the additional CB needed. I forgot about that for a moment.....That would be a pain: i have 4 strings....would need 8 fuses.
Existing dc discos and wiring would need serious changes.

BTW- the V window for the 3-5 kw TL's is very wide.

 

[PWDickerson]

I believe the new 3, 4, and 5 kW SMA TL inverters have a wider voltage window than the older models or the larger TL models. It is the 6kW and larger TL units that have a super narrow voltage window (SMA sure missed the boat on that one). But that doesn't help if you don't want to replace the USE-2 with PV wire. I would just stick with one of the older grounded units.

 

[Zee]

Yes, SMA basically designed those larger TL's to provide often only a single option in terms of how many panels in a string!
The smaller TL's - as you said - really hit the target. They have 4 major add'l features relative to their counterparts and cost the same. Amazing.
I will stick with their non-TL line for this job though, i am not taking any risks with the array wiring as it was another co's work.......

 

[ggunn]

Yes, SMA basically designed those larger TL's to provide often only a single option in terms of how many panels in a string!
The smaller TL's - as you said - really hit the target. They have 4 major add'l features relative to their counterparts and cost the same. Amazing.
I will stick with their non-TL line for this job though, i am not taking any risks with the array wiring as it was another co's work.......

Good decision, IMO. You would have to do a lot of work on the system to make the change.

I went to an SMA workshop where the question of the narrow voltage window for some of the TL models was brought up. Apparently there was an efficiency tradeoff made. I have a system in the field where if the power goes out in the middle of the day in the summertime when the modules are hot, the inverter probably won't start up again until the next morning because the string Voc could drop below the startup voltage for the TL inverter. Otherwise it runs fine; the Vmp could drop near the bottom of the MPPT window when it's running hot but it won't shut down.

 

[So Cal]

Powerone TL (& non TL) models have dual MPPT. Very flexable. An example; 11 in one string to one MPPT, 2- strings of 7 paralleled in the other. You can have different modules/orientations to the two MPPTs. Fairly wide effeciency window as well.
We upgraded a 18 year old system that needed re-roofing. The old "Trace" inverter could have been repaired, but we used a new dual MPPT, hooked up the old panels (which were in fine shape) and also added new modules to the other MPPT.

 

[So Cal]

Powerone TL (& non TL) models have dual MPPT. Very flexable. An example; 11 in one string to one MPPT, 2- strings of 7 paralleled in the other or 2 sets of 2 strings paralled with no fuses needed. You can have different modules/orientations to the two MPPTs. Fairly wide efficiency window as well.
We upgraded a 18 year old system that needed re-roofing as well. The old "Trace" inverter could have been repaired, but we used a new dual MPPT, hooked up the old panels (which were in fine shape) and also added new modules to the other MPPT.

 

[Zee]

Powerone TL (& non TL) models have dual MPPT. Very flexable. An example; 11 in one string to one MPPT, 2- strings of 7 paralleled in the other or 2 sets of 2 strings paralled with no fuses needed. You can have different modules/orientations to the two MPPTs. Fairly wide efficiency window as well.
We upgraded a 18 year old system that needed re-roofing as well. The old "Trace" inverter could have been repaired, but we used a new dual MPPT, hooked up the old panels (which were in fine shape) and also added new modules to the other MPPT.

Good points, all.

Yes, I did the same thing once: I replaced a burned out inv. on a 10 yr old system with a Power ONE, dual MPPT inv. (Since that failed immediately i have never used one again. My bias.)
You know that adding a TL inv. to a grounded system, isn't up to Code though? The issue: non-PV wire is not permitted on the new TL system. Even if you re-pulled the DC wires, the "pigtails" (module leads) are still USE-2 or worse....if 18 yrs old!
Is it a real (technical) problem? See above, i got no answer.

I agree tho...definitely pointless to repair the old TRACE - and the panels are fine, too!

Oh, and in closing the story on my end:
The customer sprung for a SB6000US. We'll solve three issues.
Replace bad 2500U,
replace the other good 2500W inverter too, that will fail in max a couple years if they are lucky (installed 2002, in full sun.....),
and get them 6 KW since the array was seriously OVER-sized at 7.3 KW......