IQ aggregator or soladeck for trunk wiring

[SunEagle]

Despite the disdain for micros expressed here, I have installed them on several buildings without the anecdotal issues expressed above.. They did solve the requirement of Rapid Shut Down and the issue of shade for me.
The Enphase manual should give you good advice on how much amperage each string can have. Thst is often expressed as a number of micros per branch. I preferred to have them each terminate at my subpanel for ease of diagnosis and other reasons related to the AC coupling capacity of my hybrid inverter. In your case since you already have the wire that can carry more Amps you may be able to combine them closer to the attic. I also found it less expensive to just use the Envoy without the aggregator, but it required a separate source of 240 volts.

I never said that micro's were bad. I just wanted to poster to understand that replacing a micro may be more difficult then a string inverter depending on it's location.

Micro's have come a long way and IMO are now much more resilient then they were when first introduced. Although the issue of changing one out because it is up on a second floor roof and in the middle of the pack has to be considered and compared to other ways to deal with equipment issues or rapid shut down.

[J.P.M.]

thanks for the input - I can consider aluminum wire, but already have 300' of 6/2 copper was hoping to use. I'll run the calculations again. I agree the the vertical feeds from the arrays would be nicer with #10 or #8. only reason I have 12 awg listed is so i can terminate with a standard enphase male connector to plug into the Q-cable array without having to cut/splice with another junction box for each sub-array. I could re-position the soladeck to the middle array to shorten the longest run

Using micro-inverters for a few reasons, (some less significant than others ):
- have a bit of shading from a tree on the garage roof as well as morning shade from the upper house
- an admittedly exaggerated concern about high voltage wiring running through the roof, attic space, house -
- rapid shutdown benefits
- module level monitoring ability benefit
- desire to minimize boxes on the side of house ( size of my system would require 2 inverters)
- not wanting to replace said inverters halfway through life of system.

FWIW: Some reasons why the smart money avoids micros/optimizers:
- More parts to fail, violating the KISS principle. You'll appreciate this when 42 inverters start to fail one by one.
- Lots of heat sensitive electronics in a harsh environment (a roof) that's usually about the hotest or wettest or coldest place around.
- Good luck when you need to get at a micro for service/replacement, especially if away from an array edge, not to mention what it does to the probability of screwing up a micro/panel if it needs removal/replacement to get at the one needing service.
Any one or all of the above are significant and good reasons to not use micros.
- Most folks get quite bored with panel monitoring after a short time. When that happens and monitoring becomes an ignored PITA, one micro failure may go unnoticed as output is not affected that much. If a string inverter fails, it becomes obvious with the first read of the next electric bill.

Have you done a shade analysis to estimate shading losses ?

[Ampster]

Despite the disdain for micros expressed here, I have installed them on several buildings without the anecdotal issues expressed above.. They did solve the requirement of Rapid Shut Down and the issue of shade for me.
The Enphase manual should give you good advice on how much amperage each string can have. Thst is often expressed as a number of micros per branch. I preferred to have them each terminate at my subpanel for ease of diagnosis and other reasons related to the AC coupling capacity of my hybrid inverter. In your case since you already have the wire that can carry more Amps you may be able to combine them closer to the attic. I also found it less expensive to just use the Envoy without the aggregator, but it required a separate source of 240 volts.

[SunEagle]

thanks for the input - I can consider aluminum wire, but already have 300' of 6/2 copper was hoping to use. I'll run the calculations again. I agree the the vertical feeds from the arrays would be nicer with #10 or #8. only reason I have 12 awg listed is so i can terminate with a standard enphase male connector to plug into the Q-cable array without having to cut/splice with another junction box for each sub-array. I could re-position the soladeck to the middle array to shorten the longest run

Using micro-inverters for a few reasons, (some less significant than others ):
- have a bit of shading from a tree on the garage roof as well as morning shade from the upper house
- an admittedly exaggerated concern about high voltage wiring running through the roof, attic space, house -
- rapid shutdown benefits
- module level monitoring ability benefit
- desire to minimize boxes on the side of house ( size of my system would require 2 inverters)
- not wanting to replace said inverters halfway through life of system.

You do understand that micro inverters may fail and replacing them is much harder then a string inverter.

[nova42]

thanks for the input - I can consider aluminum wire, but already have 300' of 6/2 copper was hoping to use. I'll run the calculations again. I agree the the vertical feeds from the arrays would be nicer with #10 or #8. only reason I have 12 awg listed is so i can terminate with a standard enphase male connector to plug into the Q-cable array without having to cut/splice with another junction box for each sub-array. I could re-position the soladeck to the middle array to shorten the longest run

Using micro-inverters for a few reasons, (some less significant than others ):
- have a bit of shading from a tree on the garage roof as well as morning shade from the upper house
- an admittedly exaggerated concern about high voltage wiring running through the roof, attic space, house -
- rapid shutdown benefits
- module level monitoring ability benefit
- desire to minimize boxes on the side of house ( size of my system would require 2 inverters)
- not wanting to replace said inverters halfway through life of system.

[Mike90250]

With your connections and splices being made under shelter ( in the attic ) I would suggest using #4 or #2 aluminum wire. Less cost, reliable if done right with anti-ox and easier to handle.
The vertical feeds from the horizontal arrays, needs to be larger than #12 copper, I suspect.

And you are using micros because why ? Rapid shutdown ? Shade issues that can't be solved ?

[ChrisBarrett]

You don't need breakers on the roof, afaik, as long as you are not switching from DC to AC right there, for example. How many branches you can combine depends on their total amperage and the gauge of the wire running to your combiner box as well as the breakers used in the combiner box.

[nova42]

HI there - came across the very helpful post while researching design of my own system. I have a question about combining branches in the soladeck.

system info (picture below):
I am planning a 42 panel system with enphase inverters consisting of 5 branches/strings of panels on 2 seperate roof sections, using a soladeck box per roof section. I wanted to combine all strings on each roof section to minimize the number of wire runs back to the Enphase combiner/envoy box. Similar to poster's option 1 and 2...

however, I do not understand the need for breakers/ fused connection on the roof if everything is going to be routed down to the breakers in the Enphase combiner box. Seems the AC combiner kits or IQ-Aggregator are pretty expensive and I would need 2 seperate AC combine kits. Is it not ok to simply tie the 3 branches together in a standard (non fused) junction box on the roof?
solar panel install.jpg

[joemadsun]

Here is a super crude drawing of my wiring. Red box is the soladeck. Blue is the Q cable. Not shown is the pigtailed female Q cables coming out of the soladeck to connect up to the Q cable.So 8x panels in the left branch and 9x in panels in the right branch

https://ibb.co/51wwp3B

And I was able to find a crimper at work that made a nice crimp

https://ibb.co/M5fkyDK

I have installed the racking and am waiting on a rough electrical inspection before proceeding to installing panels.

[ChrisBarrett]

Thanks for the warning Mike. I have some general crimping tools that should do the trick, so no worries there. Meanwhile, Joe if you get to your install before me - could you post up some pictures of how you wire the center feed? I just received delivery of all my components and I need to figure out the wiring scheme for each of my arrays.

[Mike90250]

....... Worst case I will crimp with a pliers and solder.

Yep, that's about the worst you can do. Proper crimping provides stress relief on the cable, Solder very often wicks up the strands under the insulation and makes a solid wire. A bit of play and vibration over the years and the stress of the flex wire at the edge of the solder wicking, and the wires break under the insulation. Or if the crimp is bad enough, under heavy load the solder melts and the wire falls out, with solder splashing and plasma arcing. fun fun fun

[joemadsun]

I did not buy the crimper tool. Where I work has a variety of crimp tools so I figured I can make one of then work. Worst case I will crimp with a pliers and solder.

[ChrisBarrett]

great! I'm about to apply for the city permit, and do the documentation for the utility. Did you purchase a special crimper tool for the Q cable connectors?

[joemadsun]

I am in the process of DIY install. I got my permit a week ago and equipment is arriving currently. I had to add some additional rail mounting points to common trusses in my roof due to calculations from solarstruc spreadsheet that the city of Madison uses to calculate stresses in trusses. We'll see if I run into any inspection issues, but I expect it will be a while until my first inspection.

[ChrisBarrett]

Nice! Also - did you install DIY? Curious if you ran into any inspection problems.
Thanks!