Really need some help or advice

[rodrick]

Yes you can’t have 2 mppts on a single array they will fight each other split the array up or use just one inverters mppt input

 

[WarmachineX0]

Yes you can’t have 2 mppts on a single array they will fight each other split the array up or use just one inverters mppt input

Would this cause the inverter damage? Like what I'm describing, a pop in the inverter?

Well this sucks, I changed to this because it's what tech support told me to do. Now I've got to pull the wires and run a second line. I've added a rought diagram, is this the way it should be? This is almost exactly my original plan. I do plan to add breakers for lightning, I read I needed them just recently in the manual.

 

[pvgirl]

Ok, so this is wrong? I just want to be clear.

yes

 

[pvgirl]

Would this cause the inverter damage? Like what I'm describing, a pop in the inverter?

Well this sucks, I changed to this because it's what tech support told me to do. Now I've got to pull the wires and run a second line. I've added a rought diagram, is this the way it should be? This is almost exactly my original plan. I do plan to add breakers for lightning, I read I needed them just recently in the manual.

This is the correct way

 

[Samsonite801]

Would this cause the inverter damage? Like what I'm describing, a pop in the inverter?

Well this sucks, I changed to this because it's what tech support told me to do. Now I've got to pull the wires and run a second line. I've added a rought diagram, is this the way it should be? This is almost exactly my original plan. I do plan to add breakers for lightning, I read I needed them just recently in the manual.

What are your panel specs and how many panels in each array?

Your last picture is indicating like you will have 3p1s, is that true?

Or do you have 3 panels in series?
(EDIT: Actually yeah you do, I was blind, I see the separator lines in the picture now, looks like you have 3s3p)

Is your inverter max PV input 250v (like the LV6548s)?

EDIT: What is your short-circuit amperage on each string? (panel Isc x 3)

 

[WarmachineX0]

What are your panel specs and how many panels in each array?

Your last picture is indicating like you will have 3p1s, is that true?

Or do you have 3 panels in series?
(EDIT: Actually yeah you do, I was blind, I see the separator lines in the picture now, looks like you have 3s3p)

Is your inverter max PV input 250v (like the LV6548s)?

EDIT: What is your short-circuit amperage on each string? (panel Isc x 3)

I have 3 panels in a series, 3 series per array, two arrays, total 18 panels. I think I have the 2023 upgraded inverters. I'll post their data plates so I get it right.




Also to add, I order a 15a breaker for each array. My math puts them at 9.5a, that would make a 10a too small right?

 

[Samsonite801]

I have 3 panels in a series, 3 series per array, two arrays, total 18 panels. I think I have the 2023 upgraded inverters. I'll post their data plates so I get it right.




Also to add, I order a 15a breaker for each array. My math puts them at 9.5a, that would make a 10a too small right?

I would NOT consider going 3p, that puts you at Isc 34.32a, the 6548 specs show Isc not to exceed 22.5a on each input.

Your Voc volts can go a lot higher up to 390v, so would be better to run longer strings, and max 2p, keeping in mind that 1p would be better because that inverter will start clipping amps at 18a and waste the power beyond that...

With your 18 panels, you'd be way better off to string 6 panels series into single strings, and use 3 of the PV inputs on your 6548's... That would put your Voc at 296.1v (not correcting for temp coefficient of Voc, but well below PV max volts of 390v)..

Then Isc amps on each string would be at 11.44a (well below clipping point of 18a)... You'll get most power harvest this way.

 

[WarmachineX0]

With your 18 panels, you'd be way better off to string 6 panels series into single strings, and use 3 of the PV inputs on your 6548's... That would put your Voc at 296.1v (not correcting for temp coefficient of Voc, but well below PV max volts of 390v)..

Then Isc amps on each string would be at 11.44a (well below clipping point of 18a)... You'll get most power harvest this way.

Thank you. I did have an electrician help with the plans, but they didn't specialist in solar.

Sorry, I'm having a little trouble imaging that (could you scribble out a diagram?). I should put 6 panels in a series, and run three lines to the inverters (1pv1,1pv2, 2pv1)? My panels are set up and two separate frames about 10' apart with 9 panels on each. I also have 5 extra panels, my design changed a few times on the recommendation of "pros".

 

[Samsonite801]

Thank you. I did have an electrician help with the plans, but they didn't specialist in solar.

Sorry, I'm having a little trouble imaging that (could you scribble out a diagram?). I should put 6 panels in a series, and run three lines to the inverters (1pv1,1pv2, 2pv1)? My panels are set up and two separate frames about 10' apart with 9 panels on each. I also have 5 extra panels, my design changed a few times on the recommendation of "pros".

Or if you wanted to make 4 pairs of PV wire runs, you could do:

Ground Mount #1 to Inverter #1:
4s string > PV Input 1
5s string > PV Input 2

Ground Mount #2 to Inverter #2:
4s string > PV Input 1
5s string > PV Input 2

Again, single strings keep your amps below 18a clipping limit of any one PV solar input on the inverters, so you can potentially pull max power and not lose any watts... If one has all their single strings maxed out and still want to over-panel (maybe someday later), one can do 2s and be a little over 18a, where the inverter would clip at 18a, but still the over-paneling can maximize the input potential, and give a little extra leeway for cloudy days, but that's only after you wire for close to max volts without going over on the single strings, and still want to add more. Some of it depends on how many panels you have too (to keep paralleled strings at even numbers)...

Doing the 4 PV wire runs now, will make your system more flexible for changes later (you won't have to pull more wire later).

 

[400bird]

Are your two arrays pointing the same direction at the same angle?
If so, I'd run each array of 9 as a 5s and 4s string. Parallel the two 4s strings into one MPPT and the two 5s strings into the other.

Or add a 10th panel on each mount and run everything at 5s.

9s is well over the 390 volt limit on the inverter.
3p is over the current, so your leaving production on the table if you do 3p into each MPPT

4s and 5s are about half of the 390 volt limit and over the starting voltage on the MPPT. Plus 2s is closer to the current limits on the MPPT.

Edit because of Samsonite 801's response. If you have 4 MPPT inputs (not 2) do his suggestion if you can pull that much wire through the conduit.

 

[Samsonite801]

so your leaving production on the table if you do 3p into each MPPT

I'd actually go so far as to say that 3p could actually let the smoke out of the inverters since his inverter spec sheet said max PV Isc 22.5a, so in my eyes, 2p would max to even consider (since 3p would be at 34.32a).

 

[400bird]

I'd actually go so far as to say that 3p could actually let the smoke out of the inverters since his inverter spec sheet said max PV Isc 22.5a, so in my eyes, 2p would max to even consider.

It's possible. Voltage is the one sure hard limit. Current is a little fuzzier, some MPPT will survive over current in the PV long term without issue. Others might not

 

[Samsonite801]

It's possible. Voltage is the one sure hard limit. Current is a little fuzzier, some MPPT will survive over current in the PV long term without issue. Others might not

Yeah, I know you're absolutely correct on that. Usually I've seen 2 camps of specs sheets/declarations, models that say something like, don't go over 'x' number (like one of my Victron 250|100 chargers, it says don't wire Isc for over 70a for example), where I know I can do quite a bit of parallel strings and know I'm safe)... Then the camp which they don't say what is max Isc (only list a max clipping current)..

But my view is, that in his screenshot above, it actually listed 18a (like for normal clipping current), and 22.5a for max PV Isc, so I take that a little more seriously.

Back with the last gen MPP Solar (LV6548, like the 4 that I have) for example (before they moved from 250v max PV, and upgraded to the 390v max PV), they used to only show the 18a number, so it left it up to the user to wonder what would ever be the max Isc recommendation when over-paneling (to avoid damage during MPPT sweeps or something).

There was even a lengthy thread where a forum user said he got an email from MPP Solar tech saying that 23a (or maybe it was 22a, don't remember off the top of my head), that this was the 'hard' limit on the 6548 for Isc on panel wiring.

But now it seems settled, since his above spec sheet screenshot actually lists 22.5a as hard Isc PV limit per input.. So that means only the iron-spirit folks may want to try and test beyond that on their experimental systems (my take anyways, individual opinions may vary hehe).

 

[WarmachineX0]

Thanks to everyone who responded, I'm grateful. I've read over the posts, then with the advice given came up with some options that I have all the equipment to do right now.

I've always planned on an array 3, but due to permit limits I would need to hire an engineer for the third array if it was on the permit. That's why I have extra. Just sitting on top of the conex that stores my system, but over 6' high I have to pay an engineer to look over blueprints.

I've come up with about three configurations, I'm thinking of going with #1. But wanna see if you guys think the others are better. Thanks again for all your help.

Also to add, 1p1/1p2/2p1/2p2 are the panel input ports on the inverters. Also realized I messed up #2's diagram. I put 2 strings in Parallel instead of 6 in a series.

 

[pvgirl]

Thanks to everyone who responded, I'm grateful. I've read over the posts, then with the advice given came up with some options that I have all the equipment to do right now.

I've always planned on an array 3, but due to permit limits I would need to hire an engineer for the third array if it was on the permit. That's why I have extra. Just sitting on top of the conex that stores my system, but over 6' high I have to pay an engineer to look over blueprints.

I've come up with about three configurations, I'm thinking of going with #1. But wanna see if you guys think the others are better. Thanks again for all your help.

Also to add, 1p1/1p2/2p1/2p2 are the panel input ports on the inverters.

#2 but with all panels are in series 3 6 panel series strings, and 1 4 panel series string. With the amp limit on your inverter you don't want any parallel strings.

 

[MisterSandals]

With the amp limit on your inverter you don't want any parallel strings.

I thought the SCC "amp limit discussion" ended with the amp limit being the extent of the reverse polarity protection. And, the SCC would only pull the amps it was capable of using.

Am i wrong? Still looking for that thread...

 

[Samsonite801]

I thought the SCC "amp limit discussion" ended with the amp limit being the extent of the reverse polarity protection. And, the SCC would only pull the amps it was capable of using.

Am i wrong? Still looking for that thread...

I think what I figured I learned from all the other threads, is that the charger 'could' potentially pull PV amps, up to the max battery-side amps for charging (depending on design and particular inverter), so keeping the volts higher on the PV side, will keep the amps lower on the PV side (as the battery side starts hitting maximum current rating).

But many inverters will will 'clip' the PV input when they reach their rated level (in this case being 18a), so it shouldn't pull the amps up higher (theoretically). Yet in this case in the specs sheets (from OP's screenshot above) the manufacturer is also providing a 'hard' maximum not to exceed in the physical wiring, of Isc PV max 22.5a... So there must be some merit to that concern, or why do they specify it in the specs sheet?

I know if it was my inverter, I wouldn't wire it with a circuit Isc higher than a published max PV Isc spec. I would rather wire the inputs toward the upper-end on the Voc volts (taking into account Temp Coefficient of Voc adjustment), and keep theoretical max PV circuit Isc amps under the 18a clipping point (when easy or possible), so I can get full power without seeing clipping on the harvest graphs. Because clipping means lost potential...

But going 2 strings in parallel already puts it beyond 18a clipping point, so better to keep it at single strings unless one has an abundance of solar panels and desires to over-panel to 2p on everything (where I would definitely not go 3p with these panels).

 

[Samsonite801]

Thanks to everyone who responded, I'm grateful. I've read over the posts, then with the advice given came up with some options that I have all the equipment to do right now.

I've always planned on an array 3, but due to permit limits I would need to hire an engineer for the third array if it was on the permit. That's why I have extra. Just sitting on top of the conex that stores my system, but over 6' high I have to pay an engineer to look over blueprints.

I've come up with about three configurations, I'm thinking of going with #1. But wanna see if you guys think the others are better. Thanks again for all your help.

Also to add, 1p1/1p2/2p1/2p2 are the panel input ports on the inverters. Also realized I messed up #2's diagram. I put 2 strings in Parallel instead of 6 in a series.

The main reason I suggested your Option #3, is because I don't know how far apart your arrays are, the angles on them, where the conduits are, so my suggestion to go that way, was based on convenience, since you wouldn't have to string 3 panels and 3 panels on the same series string, attempting to span the wiring across the two physical arrays.

 

[WarmachineX0]

The main reason I suggested your Option #3, is because I don't know how far apart your arrays are, the angles on them, where the conduits are, so my suggestion to go that way, was based on convenience, since you wouldn't have to string 3 panels and 3 panels on the same series string, attempting to span the wiring across the two physical arrays.

After checking, I'll need to run another conduit if I do this because I can't run 8 cables in the current pipe I have. It's about 50' to the electronics, and I'll have to install another rapid shutdown. So #3 got far more complicated than I would have liked.

#2 was your first suggestion. 6 panels in a string, 3 strings, each going to its own input. It would also be the easiest to wire as I wouldn't have to change much. There wouldn't be any issues other then just running them between the arrays, would there?

 

[Samsonite801]

After checking, I'll need to run another conduit if I do this because I can't run 8 cables in the current pipe I have. It's about 50' to the electronics, and I'll have to install another rapid shutdown. So #3 got far more complicated than I would have liked.

#2 was your first suggestion. 6 panels in a string, 3 strings, each going to its own input. It would also be the easiest to wire as I wouldn't have to change much. There wouldn't be any issues other then just running them between the arrays, would there?

Well, are the 3 panels and the 3 panels on the proposed (Option #2) split-string, pointing the same direction / angle, and one array or other array not subject to shadowing while the other is not?

In a series string, if one panel (or group of panels) get shaded or with significant difference in angle it could or will lower down output of the whole string.

On the plus side, Option #2 would leave you a full empty PV input on inverter to hook up another 6s panels later without having to mod the existing cabling layout.