Fronius IG4000 Sting Inverter - question regarding string configuration

[JanS48]

phil and J.P.M. - Thanks so much for your comments - I'm so looking forward to moving on this project - I'll keep ya all posted as to the outcome.
Thanks again
Jan

[J.P.M.]

@JanS48:

Phil is a retired M.E., and P.E (mechanical) as I am, but I was never licensed in R.I. and while I cannot speak for Phil, my guess is he isn't/wasn't (licensed in R.I) either but my opinion, FWIW, he's at least as qualified to offer opinions and advice on PV applications.
So anything, at least that I say, is with that caveat.

Still, just like P.E.'s all over the U.S., those in R.I. have a responsibility to their profession, themselves and those whose money they contract for, to act professionally and produce competent work within only their claimed areas of competency so that all such work results in safe and fit for purpose designs.
That's what you can expect to pay for.
I'd only respectfully suggest you check for the P.E's claimed area(s) of competence.
I've met a lot of P.E.s, mechanical and otherwise, who don't know much about solar energy and its quirks, particularly when it comes to residential applications.

[oregon_phil]

Greetings everyone, I'm finally making progress on my Solar Permit - the big obstacle was the PE stamp required for a Solar Permit in RI for the racking. In RI you need to have the PE stamp before you can even start to install your racking. The PE's visit is scheduled for later this week. The charge for this stamp and document is $ 600.00 - does that seem fair?

Panel installation: How close to the top of the roof should the uppermost panel be? Is there an acceptable measurement for this? I was planning on about 16 in.
Thanks in advance
Jan

The RI PE is accountable for evaluating the existing structure condition, certify the structure condition and to certify the structure can accommodate all code design loads, etc, etc. This implies the PE has/will have a solar design (panels, racking, roof penetrations, etc.) to evaluate on your structure. A solar PE in your jurisdiction should know all the applicable code requirements.

Because my solar installation was on my pole barn and not a typical truss framed house, I had to have my solar project stamped by a structural PE in 2018 for about $500. $600 seems fair in 2023. PE's, just like people are different. Some PE's are proactive and talk with the county/city before they prepare your project; others prepare your project and wait for the county/city to red line their work and them make changes. I like a proactive project management style. In other words, they will think of things in advance just like what J.P.M. listed above (i.e. inspection, cleaning, snow removal, etc). Good luck!

[J.P.M.]

Greetings everyone, I'm finally making progress on my Solar Permit - the big obstacle was the PE stamp required for a Solar Permit in RI for the racking. In RI you need to have the PE stamp before you can even start to install your racking. The PE's visit is scheduled for later this week. The charge for this stamp and document is $ 600.00 - does that seem fair?

Panel installation: How close to the top of the roof should the uppermost panel be? Is there an acceptable measurement for this? I was planning on about 16 in.
Thanks in advance
Jan

Fire and/or other codes usually/often handle the roof setback.
Also, you may want to consider ease or practical access to the array for inspection, cleaning and snow removal - especially snow removal.

If your P.E. is worth more than spit and doing his/her job, they would have considered these things and consulted with you.
For $600 they ought to give you your money's worth.

[JanS48]

Greetings everyone, I'm finally making progress on my Solar Permit - the big obstacle was the PE stamp required for a Solar Permit in RI for the racking. In RI you need to have the PE stamp before you can even start to install your racking. The PE's visit is scheduled for later this week. The charge for this stamp and document is $ 600.00 - does that seem fair?

Panel installation: How close to the top of the roof should the uppermost panel be? Is there an acceptable measurement for this? I was planning on about 16 in.
Thanks in advance
Jan

[JanS48]

Yes in looking at the overall cost I'm only looking a about 400 more to go with the TS4-A-O's I've not pulled the trigger yet but that's the way I'm leaning.
Thanks
Jan

[scrambler]

Just plan ahead. if you say not much, that implies you do have some, and if it can become more over the years with vegetation growth, plan for that

[JanS48]

Great information guys, I'll need to look into the SolaDeck terminal blocks - sounds like that's the way to go instead of a combiner box. I'm capable of doing the electrical work but at the same time I'm looking at using an electrician that installs the electrical side of solar systems as a consultant for permitting and best practices.
Regarding TS4-A-S vs TS4-A-O - I may opt for the A-S. as shading is not much of an issue.
In the next couple of weeks I should have the permit applications done for the racking (Solar permit in RI), and the electrical permit for the Inverter wiring and cabling going to the panels.
I'll let you know how it all goes.
Jan

[scrambler]

Remember that if you do not have any shading issue, you could just use the TS4-A-S (with TAP and CCA) For monitoring and rapid shutdown only, in case that saves you a bit of money.
Also less electronics in the box...

As far as I can tell the Cable between the CCA and the TAP is a standard but shielded CAT5

My only DC disconnect is at the Inverter.

[oregon_phil]

@ scrambler and oregon_phil
Thanks so much for the input. This puts things into a different perspective for me. To start with I'm only doing a single string of 10 panels. In looking at pricing on e-bay I'm thinking of the TS4-A-O modules which I can get for approx $ 46. each and I see a TAP and CCA package for approx 240. So for under 1k I'd be good to go?
A question regarding the ethernet cable - I can easily run a std ethernet cable from the TAP through the attic and thru the house back to the CCA - do you know if that will be sufficient ?

Wiring question: I was planning on having a combiner box on the roof and then using 10 GA THHN wire back to the inverter. My Fronius has DC disconnects built in so I'm thinking that is all that's needed, however I see some installations where they have a DC disconnect in the combiner box - I could put that in the attic if I needed to. My run from the panels to the Fronius will be approx 140 ft.

Grounding question: I'm using a std UniRac mounting system with support "L" brackets on ever other rafter (16" on center) the panels with be in two rows of 5 in Portrait orientation, I see some installations where they use #6 bare stranded connected to each array segment and others that use a solid #10 wire (green). It's typically not 'kosha' to run bare wire in metal EMT how did you all handle grounding ?

EMT question - should that always be metal or is it ok to use plastic electrical 'grey' PVC on exterior runs?
Thanks
Jan

I'm not an electrician nor an installer. I don't specifically know your local codes either so take any advice as potential solutions from me.

Regarding Tigo TS4-A-O, TAP and CCA: That should get your going. Just for your information, when you install them, you must assume the TIGO TS4-A-O's are ON for safety's sake. From the factory they are ON until they connect to the TAP and CCA. After that, the TS4-A-O's go on and off with the 12 volt power. just make sure the 12 volt power goes off when the AC shutoff for the inverter is turned off.

That means you could be dealing with 10 x open circuit voltage in the sun. That's why Bruce said he works in the dark. I know installers don't work in the dark. For sure installers have certain insulating practices and orders of connect and disconnect to make sure they don't kill themselves.

Roof wiring: You have one string so I don't know why you need a combiner box. My installation using one string as an example, 1 string of 10 panels; Panel 1 factory male MC4 connector, mated to Field terminated female MC4 on 10 ga PV wire red, Red PV wire to SolaDeck terminal block RED, RED SolaDeck terminal block to RED 10 ga THHN to EMT to inverter. Panel 10 factory made Female MC4 connector, mated to Field terminated Male MC4 on 10 ga PV wire Black, Black PV wire to SolaDeck terminal block Black, Black Soladeck Terminal block to Black 10 ga THHN to EMT to inverter. Assume cable glands for cable pass throughs on the soladeck. Flexible metal conduit may be an option for you. check various blogs, forums and your local inspector.

I don't have a separate DC shutoff besides what's on the inverter.

I don't know about grounding.

[JanS48]

@ scrambler and oregon_phil
Thanks so much for the input. This puts things into a different perspective for me. To start with I'm only doing a single string of 10 panels. In looking at pricing on e-bay I'm thinking of the TS4-A-O modules which I can get for approx $ 46. each and I see a TAP and CCA package for approx 240. So for under 1k I'd be good to go?
A question regarding the ethernet cable - I can easily run a std ethernet cable from the TAP through the attic and thru the house back to the CCA - do you know if that will be sufficient ?

Wiring question: I was planning on having a combiner box on the roof and then using 10 GA THHN wire back to the inverter. My Fronius has DC disconnects built in so I'm thinking that is all that's needed, however I see some installations where they have a DC disconnect in the combiner box - I could put that in the attic if I needed to. My run from the panels to the Fronius will be approx 140 ft.

Grounding question: I'm using a std UniRac mounting system with support "L" brackets on ever other rafter (16" on center) the panels with be in two rows of 5 in Portrait orientation, I see some installations where they use #6 bare stranded connected to each array segment and others that use a solid #10 wire (green). It's typically not 'kosha' to run bare wire in metal EMT how did you all handle grounding ?

EMT question - should that always be metal or is it ok to use plastic electrical 'grey' PVC on exterior runs?
Thanks
Jan

[oregon_phil]

A summary of my string inverter system built to NEC 2017.

I have an SMA 7.7 -40 with three strings on the same roof plane.

28 solar panels
28 Tigo TS4R-O optimizers
1 Tigo Access Point (TAP) on the roof
1 Tigo Cloud Connect Advanced (CCA) next to the string inverter
1 120 vac to 12 VDC transformer to power the CCA.

My installation uses 600 Volt rated ethernet cable between the TAP and CCA since it is less than 100 ft. See TIGO document "TAP/GATEWAY Communication Cable Types and Installation". The ethernet cable is strung with the DC wires inside of EMT coming down from the roof to the inverter.

[scrambler]

My detailed post above is in moderation because I included the link to the Tigo installation manual.

My configuration is using one TS4 per panel for monitoring and rapid shutdown and optimization.
If you have monitoring this requires only two additional components.
A Tigo Access point (TAP) on the roof collecting the info from all the TS4.
A Tigo Cloud Connect Access (CCA) beside the inverter to connect to the Web, and with a cable going to the TAP.

If you only have rapid shutdown, as far as I know, you only have one additional component to the TS4s, and it is One RSS transmitter on the Homerun cable from the array.
But that is probably one per string...
EDIT: Actually:
"The transmitter can be configured with one or two cores. Each Core supports up to 10 strings with a maximum of 30 solar panels per string. In summary, each RSS Core handles a maximum of 150A and 300 solar panels (Dual Core 300A and 600 PV panels)."

[scrambler]

I have one TS4 module per panel (2 strings of 9 panels each), they connect to the panel controller box, then panels are interconnected in two strings using the TS4 leads rather than the Panel controller leads
Highlight: How to install Tigo Rapid Shutdown MLPE (TS4-A-F and 2F) - YouTube

Now at the array, I have one box called the TAP (Tigo Access Point) which collects all the TS4 information. One TAP can collect 300 TS4
The TAP has a cable going down to where the inverter is and connects to the CCA (Cloud Connect Advanced) unit which interface with the Internet.

Here is the summary install sheet
64db95d1d8f20bcfea15ed4a_TS4-A CCA TAP QSG 002-00147-00 1.3 20230728 - EN.pdf (website-files.com)

[JanS48]

@ scrambler - I guess I'm missing something from what I saw on the Tigos installation you had to have an RSS Transmitter for EACH panel in the array and then an initializer which seemed to be difficult to find. If all I had to purchase was the TS4-A-0 modules and one RSS Transmitter that would certainly be a plus and I'd be able to use my Fronius inverter. Can you outline briefly the components of your installation? How many panels, Inverter used, and any other devices that make up the Tigos installation. I'm really struggling to figure out the best solution here.
Thanks to all for the comments.
Jan