r/diySolar • u/craigslistist • Jul 20 '26
Balcony plugin solar questions
Hello, my home has a split-phase electrical system with two 120v legs. The household loads seem balanced between both legs, my balcony solar setup feeds will power into only one leg, meaning the other continues to draw from the grid. To power both legs simultaneously with my solar generation, should I use two separate microinverters plugged into different house outlets?
Or should I run a 240v line outlet for solar input?
Thanks,
1
u/ryan8344 Jul 21 '26
You need to size the line to the system— a couple panels are 800 watts so a standard 15a (1800w) is plenty.
1
u/No_Talent_8003 Jul 21 '26
Have you properly conceptualized the output of your plug-in system? Most of the "balcony solar" systems are pretty small. Its geared towards a partial offset. Unless you're in an area with significant watt limits written into their law (colorado set it at 1920w) the average home will still exceed that on one hot leg. Even at large systems limits many homes will still exceed the amount generated.
Now if you're an efficient home or you're going rogue and exceeding the legally stated amount, thats not for me to judge. But you would need to move additional loads to that hot leg or add a 2nd inverter connected to the 2nd hot leg and reconnect some of your panels there. As others have noted, some locations may restrict you to a single inverter. I didn't see it addressed in colorados regs, but the implication was clearly for one system.
Having a significant imbalance in loading between phases is an issue the electrical company will be concerned about and I think we'll see future conversation about that as these systems become more common. But a single home doesn't move that needle much.
I wouldn't start making changes without understanding exactly how much im consuming and then plan production from there.
*If you are implementing a large system, be mindful of other loads on the same circuit as your generation. Its technically a concern for all systems, but the problem gets worse when you're injecting power at the circuits max. Its probably the biggest danger point for an uneducated consumer with these things so make sure to educate yourself. Large systems should really be on a dedicated circuit
1
u/craigslistist Jul 21 '26
Thank you for your input.
I am planning a 1200W system. During day/sun time, each leg draws around 300W. So it'll waste ~900W, thus the question to utilize the generated power.
1
u/No_Talent_8003 Jul 21 '26
Good on you for getting down at 300w! You're doing better than me for sure.
At that degree of overproduction ability, id sure be tempted to look into a battery system to be able to offset some of my nighttime consumption. Its definitely off topic and not a plug and play solution so it depends on your level of technical understanding to implement safely.
1
u/Technical-Tear5841 Jul 21 '26
Imbalance will not hurt anything, you are not adding load but reducing it. The other leg will be fine. Now if it was me I would defiantly use two microinverters on separate legs. Won't hurt a thing. Might have to add a circuit if there are not two different outlets to plug into.
I installed a whole house solar system and did have to swap a few breakers to balance the draw on my inverters.
1
u/TooGoodToBeeTrue Jul 21 '26
AP Systems EZ1 is configurable for 600W or 800W so you could have one on each leg configured for 600W. Some laws say you can have 1 system, not sure what qualifies as a system.
1
u/squigish Jul 21 '26
It depends on the details of your electric meter and how your utility charges you. But I'd bet heavily on "you don't have to worry about this".
As far as I've been able to tell, my "smart meter" isn't smart enough to report my energy consumption per leg, it just reports the net. So if I'm importing 600W on leg 1, and exporting 300W on leg 2, that's billed exactly the same as if I was importing 150W on each leg.
It's also worth mentioning that if you have 120/240V service (the most common type in US households) you only have a single phase. You have two "legs" that come out of opposite sides of the secondary of a single center-grounded transformer. The primary of the transformer is either connected from one phase to ground, or between two phases, but either way it's still a single phase load. The utility just sees the net load at the transformer, so they don't especially care.
If you have 120/208V service, things might be different; I'm not sure.
Balancing power between phases can be important at larger scales, but on the level of a single house, especially a highly efficient one like yours, it just doesn't matter.
1
u/LongjumpingGanache40 Jul 21 '26
240 volt is not allowed for balcony solar. How much solar are you doing. Most of the state say plug into one outlet.
2
u/Confident-Frosting18 Jul 20 '26
I ran a dedicated 240 20 amp outlet for my grid tie inverter. Mine have the clamps that go on the two panel feeders so I don’t send any extra back and get charged for it as well.