How many strings should I have?

[galley123]

So I have 16KW system 2 Tesla inverters and 4 PW waiting on PTO. I have been testing to make sure everything is working. My inverters show 4 active strings on 1 Tesla Inverter and 2 on the other. Sometimes it's 3 instead of 2. How do I figure out how many strings are setup? I have looked at the diagrams, and it's still not clear how many active strings I should have. I'd like to make sure how many strings I have, and that all strings are active.

Any help would be appreciated.

Thanks,
galley123

 

[jjrandorin]

I would say "welcome to TMC" but it seems like you have been here since March, so I will say, "welcome to your first post / thread". These are construction projects, so I dont think there is such a thing as "how many should I have?" for something like this. There are likely guidelines, and "dont have fewer than this" or "dont have more than that" but "should have"? I dont know.

I would think some of our more technically minded members might be able to help you determine what you have, if you post pictures of your diagrams, etc, with your personal information blacked out.

 

[galley123]

Thank you for the "welcome". I have added my wiring diagram that I think has the information needed. It wasn't completely clear to me how many strings. Thank you!

 

[galley123]

Here is a better quality image. Many thanks to anyone who can help.

 

[BGbreeder]

You have 48 panels arranged in five strings; look at items 1-5 on the wiring chart, and at the MP labels. Two strings of ten, two of seven, one of nine, and one of five. (Math checks out at 48, matching the module count in the lower left.)

All the best,

BG

 

[galley123]

Thank you! Thank you! Thank you! This will help me figure out if all the strings are working. In the Tesla Inverter I see 4 active in 1 inverter and 2 in the other. I would of expected 5 total. Is there a "Dummy" string for each inverter?

Thanks,

Galley123

 

[galley123]

I'm trying to relate how many DC Strings the inverter says is connected to my strings on the roof. Are these two numbers not a 1 to 1 relationship?

 

[arnolddeleon]

The 7.6 kW Tesla inverter has 4 Maximum Power Point Tracking (MPPT) inputs but they can be used in parallel. I suspect the strings of 10 are connected to 2 inputs on each inverter to have enough capacity. That's why you are seeing an extra string on each inverter.

 

[galley123]

Thank you

 

[Bitslizer]

The 7.6 kW Tesla inverter has 4 Maximum Power Point Tracking (MPPT) inputs but they can be used in parallel. I suspect the strings of 10 are connected to 2 inputs on each inverter to have enough capacity. That's why you are seeing an extra string on each inverter.

Looking like the 2x7 on the bottom inverter. You can see they use 1 run to the inverter but split it into 2 mppt before entering the inverter in parallel

 

[arnolddeleon]

Looking like the 2x7 on the bottom inverter. You can see they use 1 run to the inverter but split it into 2 mppt before entering the inverter in parallel

You are correct according to the diagram. Of course Tesla doesn't always wire exactly according to the diagram. The OP reported 4 inputs being active on Inverter 1 and the diagram shows only 3 so suspect there is another set of inputs being used in parallel or the string of 10 became two strings of 5 (or something else). We can make educated guesses if the voltages and current reported by the inverter are shared and roughly what the time/conditions were.

If the OP is comfortable opening the inverters they can post a photo of the inverter terminals and we can know for sure how the strings are wired to the inverters. We definitely can figure out how many inputs are in use. What we can't tell is if Tesla did any paralleling outside of the inverter. We know they do this on the roof sometimes.

 

[jjrandorin]

OP, I told you we had some active members in this section who could probably answer your question, if you posted the diagram

 

[galley123]

I'll get some photos....

 

[galley123]

Photos from inverters

 

[Bitslizer]

Photos from invertersView attachment 687033

seems 3+/4+ and 3-/4- are jumpered together?

Is there 3 black and 3 red wires connected? what are the bottom rows labeled? only see 1 labeled as 2+

looking closer, i think the bottom are labeld 2+/4+ and 2-/4-. if there's a cable for 4+ and for 4-?

seems like 2x stand alone strings with 1x parallel string, String 1, String 2, with String 4 connected but Jumpered (parallel to handle higher Amp) to string 3. So this would show as 4 strings on the inverter

I would think this is the 4 active string inverters you are referring to.

The wiring doesn't seem to match the 3 lines diagram, but the installer can adjust/modify at the site.

Did they tag or label the black and red wires? one of the black wire seem to have an orange label?

Do you have pictures of the 2 or sometime 3 string inverter?

 

[galley123]

Thank you, I may need to check the mppt on the roof. I thought both photos uploaded here is the other one.

 

[galley123]

BTW what a great forum, and thank for the help.

 

[Bitslizer]

Thank you, I may need to check the mppt on the roof. I thought both photos uploaded here is the other one.View attachment 687472

This one has 3 string, 1 single at 3 and a parallel at 1 and 2. If this one is some time 2 sometime 3, try pushing in the jumpers to make sure they are snug... Also the black and red at 3+/- Maybe at night when the panel aren't generating.

Mppt is part of the inverter, what are you checking on the roof?

 

[arnolddeleon]

Photos from invertersView attachment 687033

3/4 are jumped together. A "big" (most modules) string connected in the bottom connector which ends up going to both 3 and 4. When you look a the inverter status you should see stringers 3 and 4 pretty much.

On the second inverter 1/2 are jumped together so you will see 3 inputs. String 1 and 2 should match. The "big" strings should be there.

 

[galley123]

When I look at inverter status how many active strings should I see? 4 in one, and 3 in another?