Solar Help!! | Panel and Inverter questions

[kronic24601]

So, I apologize if this is a seemingly simple question but I'm going to ask anyway. I've been back and forth on options and I was about the pull the trigger when I realized that my plans had some holes in it. Hoping someone can set me straight.

Notes:

• I had a layout plan of about 28 panels (60 cell) on my roof.
• I have a 200 amp panel (200 amp main breaker)
• I consume about 15,510 kWh per year (pool, AC, big house, etc.)
• I wanted, ideally, a system rated just under 10 kWh.

Question 1: In my county (Los Angeles), there is a simplified permit check and a standard (comprehensive). Ideally I'd go through the simplified one as I'm not a licensed electrician (owner builder). One requirement for simplified is that the module ISC must be lower than 9.6 Amps. However, at least for STC rating, it seems that a lot of the higher wattage modules are all over this annoyingly. (SUnmodule 290/300 mono, LG 300+ etc... I've only found one that isn't ... "Solaria POwerXT 330"). As you can see, I was hoping to have a module with a high efficiency rating. --- Is this common in other areas? It seems strange to me as so many modules have a higher rating. Does anyone know if I can use the NOCT rating instead? These all have a lower ISC and could be allowed? I can follow up with my building and safety but curious how it's done elsewhere. (no where on the plan check does it specify STC vs NOCT) ... it just says "from module nameplate", but I'm not sure what would be stamped on the module plate does anyone know?

Question 2: As I stated, I would like to have a 28 panel design -- however this appears to be a problem again. If I assume two circuit branches that's 14 panels per branch (string).

• Microinverter -- I was considering Enpahse IQ6+ -- This only allows 13 per string as per the documentation here.
  • Obviously now I'm looking at either downgrading to 26 panels (possible) or moving to 3 branch circuits. However, that would require a 50amp breaker which I am not permitted on a 200 amp panel without upgrading the panel or downgrading the main breaker (all of which will require non-standard permits and more money than I'd like to spend). So it seems like Micro-inverters are only viable with 26 or fewer branches (at least for the higher power panels). How are you guys doing these?
• String Inverter -- I was considering the SolarEdge 7600H -- This one confuses me a bit, the power optimizers (P370) say that the max string length is 25 optimizers and max continuous power is 5250 watts (documentation here) --- so on one hand these seems like the only option that will allow me to use 14 panels per string (branch). However, when reviewing the permit application in section 7. Maximum System DC Voltage (Use for systems without DC/DC converters.) -- they make me do the following calculation.
  • Module Voc (44.5) x # of modules in series (14) x Cf (1.12) = 697.76 V. Then they have a table that says "Max # of Modules for 600 Vdc" and it says "12" ... so I don't understand this. Can anyone help explain? Why is the 600 Vdc relevant?

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[ButchDeal]

You are far better off with solaredge for this size system

solaredge has dc to dc converters so you can skip those requirements 600v string requirements.
also the 7600is too small of an inverter for your size system. I would go with the SE11400.


also in your string length issues. For solaredge you have to meet both requirements of strength length ( count) and string wattage.

[kronic24601]

ah interesting. I didn't realize the Power Optimizers were considered Dc to Dc converters. That makes sense. There is a separate permit section for that.

As for the inverter size -- I read that oversizing is preferred. Solar Edge says up to 155% here: https://www.solaredge.com/sites/defa...zing_guide.pdf

Plus I'm not able to place my modules in ideal placement but perhaps you are right... I'll look into that closer.

[littleharbor]

Here's a label from an older module, but it appears Noct numbers don't contain Isc. or Voc. Not sure if this helps but I had remembered these values weren't in the NOCT side of the label,

Kyocera KC-125 data.jpg

[ButchDeal]

As for the inverter size -- I read that oversizing is preferred. Solar Edge says up to 155% here: https://www.solaredge.com/sites/defa...zing_guide.pdf

Plus I'm not able to place my modules in ideal placement but perhaps you are right... I'll look into that closer.

you are allowed under warranty but wether you want to is dependent on the layout. If you are east / west ovetsizing would not cut production. All south facing, it would.

[GRickard]

also the 7600is too small of an inverter for your size system. I would go with the SE11400.

By my calcs, the 7600 would do the job but still I agree with Butch. I would spend a little more ($400 or so) and go with the SE10000. You get the fan cooled inverter that runs a lot cooler and has capability for three strings if needed. I've installed the 7600 next to a 10000 and it is a very noticeable temp difference.

[kronic24601]

Ya, I'm pretty much all West facing. Technically I have (plans for) two arrays one at 270 and one at 235. The heat is interesting, for some marketing reason I'm sure I assumed that the "HD" inverters had some superior performance/value (It says SMART on the box so ... you know ... smart and stuff).

My main issue is size. I really want to mount it outside but due to my house arrangement this will prove tricky. If I move into the garage (really don't want to), then I wanted to keep it limited.

Any other specific pitfalls I should be looking for? Running cooler seems like it would be more efficient.

[kronic24601]

Here's a label from an older module, but it appears Noct numbers don't contain Isc. or Voc. Not sure if this helps but I had remembered these values weren't in the NOCT side of the label,

Thanks littleharbor. I guess I have to either go with the Solaria panels, or move to a comprehensive permit plan if I really want those higher amperage modules.

[ButchDeal]

Ya, I'm pretty much all West facing. Technically I have (plans for) two arrays one at 270 and one at 235. The heat is interesting, for some marketing reason I'm sure I assumed that the "HD" inverters had some superior performance/value (It says SMART on the box so ... you know ... smart and stuff).

My main issue is size. I really want to mount it outside but due to my house arrangement this will prove tricky. If I move into the garage (really don't want to), then I wanted to keep it limited.

Any other specific pitfalls I should be looking for? Running cooler seems like it would be more efficient.

Yep you go from 98% to 99%. But if you are one or close to one direction then you will clip with the 7.6kw unit verses the 11.4 kw. I would skip the 10kw for the 11.4 though.

[kronic24601]

One question I do have about that though. Woulding I need to have a larger breaker in my main panel? According to this documentation the "Max Continuous Output Current" is ..

• US-SE10000A - 42 Amps
• US-SE11400A - 47.5 Amps

So I'm assuming I'd need a 50amp breaker for either of those right? If correct, I'm likely not able to without upgrading my panel or downgrading my main breaker. Unless I'm missing something.

[ButchDeal]

One question I do have about that though. Woulding I need to have a larger breaker in my main panel? According to this documentation the "Max Continuous Output Current" is ..

• US-SE10000A - 42 Amps
• US-SE11400A - 47.5 Amps

So I'm assuming I'd need a 50amp breaker for either of those right? If correct, I'm likely not able to without upgrading my panel or downgrading my main breaker. Unless I'm missing something.

Depends on your service panel. Generally anything larger than a 7.6kw has to have a special connection like a Line side tape do to the 120% rule for feedin.

[kronic24601]

Thanks ButchDeal.

Here's another question. Any reason I can't use any random AC fuse-less disconect like this? https://www.lowes.com/pd/Eaton-60-Am...lic-Ac/1114583

All the ones I've seen visibly have a throw switch, but I don't see anything in my code about that. Curious if anyone knows (did some forum searching but came up empty).

I've seen some normal duty and heavy duty ones, but not sure what's required.

Heavy duty: https://www.homedepot.com/p/Siemens-...222N/205874536

[ButchDeal]

Thanks ButchDeal.

All the ones I've seen visibly have a throw switch, but I don't see anything in my code about that. Curious if anyone knows (did some forum searching but came up empty).

I've seen some normal duty and heavy duty ones, but not sure what's

Use it for what? An AC disconnect sure but you will need a fuse someplace.

[kronic24601]

Yes, for the AC disconnect. I actually have to have two (one by the inverter, and another by the main panel). Are fused disconnects a requirement? I don't see anything about that in my code guidance. Or is it just a nice to have? I was going to just have it feed directly from the inverter to the 40amp breaker in my panel (with the above mentioned disconnects)

[ButchDeal]

Yes, for the AC disconnect. I actually have to have two (one by the inverter, and another by the main panel). Are fused disconnects a requirement? I don't see anything about that in my code guidance. Or is it just a nice to have? I was going to just have it feed directly from the inverter to the 40amp breaker in my panel (with the above mentioned disconnects)

40amp will work for the 7600 inverter but not for a larger inverter.
you need a fuse someplace between the inverter and grid.
it does not have to be a fused disconnect but that usually simplifies especially if you are using a Line side tap.
if you are connecting to the service panel then the breaker in the panel counts as a disconnect method.