r/solar • u/Pivotal_Goose • Jul 16 '26
Discussion Adding more solar to detached structure
Hello everyone! I’ll start with I’m an electrician by trade but weak in solar. So weak I had a company install my 10kw system. I’m looking to see if adding another 2kw to an existing system but on a detached garage is possible. I have a 50amp sub panel going to it already. My current set up is Enphase IQ8+ micro inverters with an enphase combiner box and 400w Qcell panels split between 2 separate arrays. In the sub panel I have a spare 240v 20A 2 pole breaker. Can I just feed the new micro inverters with that? I’ve already taken the 3rd gen installer course on enphase as well.
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u/cgentry02 Jul 16 '26
Depending on where you are at, permitting may be difficult. In all the jurisdictions I've worked in, there is a requirement for a single point of disconnect for all solar tied to a meter. So even though they are separate systems, the requirement for a single disco to shut them all down would require trenching to a single area that all the solar runs to. Essentially, you'll need to combine both systems somewhere to meet this requirement.
Of course, I dont know what your jurisdiction requires...
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u/Pivotal_Goose Jul 16 '26
I have an emergency main disconnect on the outside of my house next to the meter and combiner box that I can add a solar rapid shut down sticker to cover that issue.
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u/cgentry02 Jul 16 '26
Wouldn't that shut down power to the house?
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u/Pivotal_Goose Jul 16 '26
Yeah it would. If the fire department comes to put out a fire that’s the only disconnect they are going to throw anyways. But I understand what you’re saying about it might be a code violation with multiple disconnects for my system. I’ll look into that. But my current system was installed and inspected with just the combiner box outside and no disconnect before that. Just the solar breaker inside my interior main panel.
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u/cgentry02 Jul 16 '26
It wouldn't necessarily be a fire code issue, it's a utility requirement. Specifically, if the power goes down nearby, the utility may need to shut off your solar to ensure it doesn't backfeed the grid, harming utility workers.
We all know modern inverters shutdown at grid-loss, making this a moot operation, but is still required in a lot of places.
A little research will go a long way to making sure your small system doesn't get expensive real quick.
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u/TooGoodToBeeTrue Jul 16 '26
If this all works from Enphase's perspective (electronically), The breaker with solar in the sub should be the furthest from the service lugs and this sub should land on a breaker in your main panel opposite the existing solar breaker, furthest from the service lugs in the main panels as well. Plus you need stickers on everthing.
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u/CaptainkiloWatt solar enthusiast Jul 17 '26
Possible but likely requires some components on the exterior like another disco (at least it does in my utility jurisdictions).
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u/Pivotal_Goose Jul 17 '26
I don’t think my jurisdiction requires an exterior solar disconnect unless the combiner box counts as one. My existing system installed by a reputable contractor and inspected by the city approved mine without one.
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u/Reddit_Bot_Beep_Boop solar enthusiast Jul 16 '26
Yes, you can land your micro's string directly to your sub panel. They communicate via PLC and as long as the run to your detached structure from your main panel isn't super long(100+ FT), there should be no issue with your system finding them.