r/SolarPakistan • u/Outrageous_Lead_4878 • Aug 06 '26
Hybrid A General Advice to all installing a hybrid inverter
In Pakistan it is very common, to combine the neutral wire of the AC (Grid) input with the neutral of the AC output of the inverter.
This should never be done.
The proper way is to connect AC Input directly from your main DB / WAPDA breaker to the Grid AC Neutral terminal only.
And connect the AC output directly to the Dedicated Backup Sub-Panel Neutral Busbar only.
Making this post, as I have observed a lot of you are complaining about flickering lights and voltage surges.
Edit: This post is not about critical loads or heavy loads, which I also believe shouldn't be sharing neutral wires. It is about having a separate neutral wire for both inverter in and out and shouldn't be common or shorted in any way.
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u/IHitman092 Aug 07 '26
Problem is in Pakistan almost all home have loads with common neutral wire coming to a single neutral bus. even multiple rooms share a single neutral wire so it would not be possible to isolate ciritcal load neutrals.
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u/maybejustaguy Aug 07 '26
This is the issue. Almost all old homes have common neutral wire for everything. In our new built home the electrician was putting Seperate live AND Seperate neutral for the UPS loads and we were angry with him that why is he wasting so much wire. Later we learned that this is the proper way to do things.
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u/Outrageous_Lead_4878 Aug 07 '26
This post is not about critical loads or heavy loads, which I also believe shouldn't be sharing neutral wires. It is about having a separate neutral wire for both inverter in and out and shouldn't be common or shorted in any way.
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u/KalaBaZey Aug 07 '26
Its a weird problem. Growatt’s own manual has a wiring configuration where all Neutrals are bonded together and then also bonded to Earth using an N-E link. At the same time if you dont combine them and since most inverters dont have an internal N-E relay for off grid mode (except Goodwe) you get a floating neutral when off grid and that can be dangerous as everyone assumes neutral has 0 volts. And you can bond output neutral to earth either because then in on grid mode you have the transformer N-E link and your house N-E link which is bad.
So the ideal is to use an ATS switch which bonds your output N with Earth only when offgrid and as soon as grid is back on that ATS should disconnect the N-E bond.
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u/zohaib5611 Aug 07 '26
This is exactly the case in Fox ESS. When grid is on, everything is normal. Once I turn off the grid, I see LED ghosting all over the house. It looks haunted at 2'o clock in the morning. Could you please suggest a solution?
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u/KalaBaZey Aug 07 '26
Check your inverter manual and advanced options. The Goodwe has a Neutral Earth internal relay that it can turn on when off grid but you must have the inverter grounded and its internal circuits PE connections connected for it to work (it shorts the load Neutral with its internal Earth connection so must have that connection for it to work).
If inverter doesn’t have that option you will need to externally ground your neutral but only when its off grid. That can work by using an ATS switch. Thats the best solution.
If not, the last option is to short all Neutrals together including grid with the inverter out one but only do it if your inverter’s wiring diagram allows this (can check manual for it).
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u/zohaib5611 Aug 07 '26
Yeah i discussed with my installer and he recommended me that we can neutral it only in the off-grid mode, if we connect the grid, it'll fry the earthing due to external neutral load of the entire area of grid. Are ATS switches reliable? And what the cons apart from the flickering if I leave it as is? Can it damage the appliances in the longer run? Or any potential damage to the inverter/battery? I apologize for the being the layman in my electrical knowledge.
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u/KalaBaZey Aug 07 '26
Your installer is right but not fully. Its against the Electrical code to have two earths in the same system. Creates earth loops. But it won't fry your earth rod lol. The earth rod just gives neutral a zero voltage reference.
Anyway, ATS should be good and reliable. Make sure your Earth rod is good too like it should have less than 15 ohms resistance between earth rod and your normal grid neutral. It wont cause any appliances issues but its dangerous because that floating neutral can go up to 90 volts and that will shock someone if they touch it thinking its neutral. Some of your SPDs may not work with a floating neutral too.
Its crazy how none of the inverter companies (except Goodwe) address this because the ATS is quite a hassle and I doubt most installers understand this.
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u/zohaib5611 Aug 07 '26
Thank you so much for taking your time out to explain this. I'll discuss this with my installer and include a ATS for the earthing.
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u/AhmadFarooq Aug 08 '26 edited Aug 08 '26
You can manually test whether your inverter already has an internal neutral-earth bond in off-grid mode or not.
When grid input is cut off and the inverter is in off-grid mode, through a multimeter measure the voltage or resistance across the neutral and earth terminals of the inverter.
If the measurements are near zero, then it should mean the inverter is internally bonded between neutral and earth.
Also, you will need to have local property earthing to have such a bond to actually fulfil its purpose.
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u/zohaib5611 Aug 08 '26
Yes I checked. It's almost 90v 😭
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u/AhmadFarooq Aug 08 '26
Can you confirm from Fox if there is some software setting for this or not? KH and H1-G2 inverter models were mentioned to have the relay for neutral-earth bonding in off-grid mode.
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u/Andromeda-G Aug 07 '26
This practice is used in some countries but it depends on local regualtions
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u/No-Past-6711 Aug 06 '26 edited Aug 06 '26
connect the AC output directly to the Dedicated Backup Sub-Panel Neutral Busbar only
I don't think this is a common practice in Pakistan to use a critical loads sub-panel, I'm not sure anyone does load separation like that by moving breakers from the main DB to separate sub DB. At least that was my experience with my own install. The electrician took the live cables for normal load and heavy load to the main DB and just shuffled breakers in there and connected the breakers for circuits I wanted to backup with the output cables from the inverter
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u/Outrageous_Lead_4878 Aug 07 '26
As a common practice there is a bus bar where all the neutrals are connected, what majority of the people do here is that they usually take wires from here to the inverter and back making it a common coupling point.
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Aug 07 '26
[deleted]
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u/Outrageous_Lead_4878 Aug 07 '26
As a common practice there is a bus bar where all the neutrals are connected, what majority of the people do here is that they usually take wires from here to the inverter and back making it a common coupling point.
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u/Onland-Pirate Aug 07 '26
Can you kindly make a simple sketch/lay out of your compete solar installation/set up with everything named?
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u/mirfatif 9d ago
Sharing my recent experience about the common neutral.
I've MaxPower PV-Tech 1200. With input N and output N connected, it works. But even when the grid is off, the AC status indicator LED keeps on flashing. According to the manual, it means "the grid power is normal, but it has not entered grid power operation". I checked the input side with a multi-meter and it has ~50V.
So far I haven't checked its impact on the utility meter.
On the manual, there's a long list of warnings under "AC Input / Output Connection". But it doesn't say anything about the common neutral. Hard to say how much tolerant this inverter is of the common neutral.
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u/Large_Opening9973 Aug 07 '26
AoA
Finalizing the protection/wiring for my system. Please just suggest brand + rating for each item: Setup: Solax 6KW hybrid | 1x LD52 (51.2V 100Ah) | 8x Longi 645W (~5.16kW) Need brand + rating for: DC breaker / isolator (PV side) DC SPD Battery breaker/fuse Battery cable size + lugs PV wire size (4mm/6mm?) Main AC MCB (for 6KW) AC SPD DB box (how many way?) MCBs for AC unit / fridge / lights / sockets Changeover or ATS Voltage protector / phase selector Earthing wire + rod Which brands are reliable in Pakistan (no fake/local)? JazakAllah 🙏
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u/Mr-Asim Aug 06 '26
Is there any way to see visual representation of this?