Can you please review & give feedback on my Single Line Drawing?

I have attached the Single Line Drawing as an image.
Can you please review to see if I have missed any components or if I have OVERDONE anything with redundant parts?
Thanks, so much, for your feedback.

Macho… The only thing I can see … Not knowing much about your system… Mine is not feeding the grid…
The open circuit voltage… It maybe an issue with your controller if you use one…May not be an issue… It was for me for I could only put 4 panels in series hitting 180 volts. 200 was my max open circuit voltage. Mine is stand alone… Again… Not sure how a ‘grid tie’ system works…my 2 cents…Gerry

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Thanks for looking! I may be more ignorant on this than i thought…
The model IQ7 EnPhase microinverters support up to 16 units interconnected to make a branch. I’m doing 15 units in a branch, output for each branch will be 240V at 4.575 kW (305W per panel).
Each end of the branch is terminated into either the last inverter or the combiner box.
Were you concerned about the total voltage per branch on those long branches?

found an error… there will be a 50A breaker to the outbuildings… not 40A… I was only counting 28 panels.
36panels x 305W each = 10.98kW / 240V = 45.75A

Macho… You are good… I’m all wet… Hi… I am not familiar the way a grid tie system works… I am off grid… Using batteries. My panels are in series… 4 at 42 or so volts each. I have to stay under 200 volts with my charge controller. ( open circuit ). So what I was thinking in your system does not apply… Later…Gerry

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that’s very cool. i can’t do off grid unless me wife leaves me… or right before she would leave me.


afaik you need to specify the fuse rating in the AC disconnect for the first 5 branches.
Since you are using supply side connection it needs to be 60Amp or higher (up to 200 amp rating of your main service panel).

NEC specifies 20% rule of your main bus bar, so the max fuse of the breaker to the outbuildings = 20% of 200 = 40 amps MAX.
I think you should try and tie all solar to the supply side .
the fused AC disconnect (eg 100 amp) should go to a subpanel and from there connect all branches with individual breakers.
Would also make it easier to measure your solar generation with your sense ct’s :wink:

Just my $0.02

i have some real routing problems of the outbuildings due to poured sidewalks, raised flower beds, wooden deck, etc. The green line from the out buildings is an already existing #2 AWG to my main panel.
i didn’t want to fuss with maxing-out my panel and using the 120% rule. I wanted to connect all i could to the meter… but i may have to reconsider calculating my main panel to see if it’s possible to route everything through it (probably over 30kW) – i’ll need to recalculate…

Hi Macho,

Panel wattage above the Enphase listed output which for iQ7 is only 240w continuous with peaks at 250w means that any solar panel you connect to it that has a wattage above that amount will be curtailed to primarily operate at 240w. For your outbuildings at 240v it’ll only ever put out 37.5amps so a 40a breaker is fine, if you have a 50a breaker there, that’s also fine. You said the line is #2 which is 115a ampacity so no problem there either.

If your house array is connected line-side of the house panel main breaker, which is what it appears to be, you’re safe there and not over-amperaging your main panel. If you wanted additional protection, you could land your 5 branches of 15 above the 200a breaker in the meter, but below the meter (assuming there is one), which would then provide additional protection because it would be a connection outside and protecting all the interior wire runs.

Depending on your utility, you could also use a product called ConnectDER which adds a breaker to the ring the utility meter globe plugs into and you can then land I believe up to 80a of PV there, which you’re at 65a with your 5 BC of 15 so no problem there. But you have to see if that device is accepted by your utility.

Good Luck!


unfortunately i pretty much have to redesign everything. I need to add Snow Guards to the roof due to some very slight twists my new gutters have due to ice dams… so that steels real estate from my roof. Also, the LONGi AC Modules are sold-out. I’ll be rewriting the plan and post it in the forum. Thanks for the feedback, so far!!