Off-GRID "N" (neutral) with GRID "N" is that Possible?

[night_angel]

I have this question, it is possible to connect the Off-GRID "N" (neutral) wire from inverter, to the Home "N" wire? we are talking about neutral, not from the ground.

because I want to work with the 2 together, one part of the house with GRID, and the other part with my solar off-grid,

the problem is that the most part of the house has only one neutral..

example: the kitchen, living room and room 1 (1 negative, and 3 positive) but I want to power my room 1 with the off-grid system.

I know that normally, makes a separate system, but I want to know if I can do this, this way too?


thanks


thomas willms

[Mike90250]

if it is a mod-sine inverter = NEVER. Mod-sine inverters bias their sine wave around the (-) battery terminal, +- 60V, and if you ground one leg of the output, you create a shock hazard at the battery, or will blow the inverter.

Pure sine inverter = Technically possible, but you must have an interlock in the panel, to prevent any chance of the Grid ever contacting the hot buss. If that happens, the grid wins, and your house gets very smokey.

[night_angel]

if it is a mod-sine inverter = NEVER. Mod-sine inverters bias their sine wave around the (-) battery terminal, +- 60V, and if you ground one leg of the output, you create a shock hazard at the battery, or will blow the inverter.

Pure sine inverter = Technically possible, but you must have an interlock in the panel, to prevent any chance of the Grid ever contacting the hot buss. If that happens, the grid wins, and your house gets very smokey.

I will have ready my 10kg fire extinguisher


thanks for answering..


i have this inverter

http://www.amazon.com/gp/product/B009X6XSMO/ref=oh_details_o03_s00_i00?ie=UTF8&psc=1

, Semi-Pure Sine Wave (SPSTM), seems to be better than a Mod-sine inverter..

I would have bought something really better than this...

[Sunking]

Neutral = Grounded Circuit Conductor

[inetdog]

I will have ready my 10kg fire extinguisher

, Semi-Pure Sine Wave (SPSTM), seems to be better than a Mod-sine inverter..

I would have bought something really better than this...

The SPS (TM) seems to be a variation on MSW in which at some point at least one additional square step is added to the voltage waveform to make it a bit closer to sine than simple MSW. I doubt that it helps much, since there will still be sharp transitions, just not as pronounced.

There is one thing that has not been mentioned to be very careful of when you change the source of one of the hot wires and share the same neutral:
When you drive two 120 volt circuits of opposite phase (from what we call split-phase 120/240), the current in the shared neutral wire will be less than or equal to the current in either of the phase wires. This allows the neutral to be the same size as the phase wires. (A pure 240 volt load, phase-to-phase, will not send current through the neutral at all, for example.)
But when you put an independent source like an inverter on one of the phase wires, it is no longer coordinated with the other source(s) and as a result the current in the neutral can be as much as the sum of the currents in the two phase lines. This can overload the single neutral wire with up to twice its rated current. Not a good idea!

[Sunking]

Night Angel you cannot do what you want period. The grid system and off-grid system are required to be completely independent and isolated from each other. They cannot share any common wiring. In fact the wiring of the two systems has to be separated. The only thing in common with them will be the Earth Ground where both systems are referenced together. As I sated earlier Neutral = Grounded Circuit Conductor. So the Earth Ground connection is the only common point the two systems are connected.

[inetdog]

Night Angel you cannot do what you want period. The grid system and off-grid system are required to be completely independent and isolated from each other. They cannot share any common wiring. In fact the wiring of the two systems has to be separated. The only thing in common with them will be the Earth Ground where both systems are referenced together. As I sated earlier Neutral = Grounded Circuit Conductor. So the Earth Ground connection is the only common point the two systems are connected.

Note that this complete separation is only required if you want to be legal and safe.
Which this forum certainly encourages.

[night_angel]

I want to tell you that I'm from Paraguay, South America, here we have 220v "hot wire" circuits only... here a little more about me ...

http://www.solarpaneltalk.com/showth...-South-America!

The SPS (TM) seems to be a variation on MSW in which at some point at least one additional square step is added to the voltage waveform to make it a bit closer to sine than simple MSW. I doubt that it helps much, since there will still be sharp transitions, just not as pronounced.

There is one thing that has not been mentioned to be very careful of when you change the source of one of the hot wires and share the same neutral:
When you drive two 120 volt circuits of opposite phase (from what we call split-phase 120/240), the current in the shared neutral wire will be less than or equal to the current in either of the phase wires. This allows the neutral to be the same size as the phase wires. (A pure 240 volt load, phase-to-phase, will not send current through the neutral at all, for example.)
But when you put an independent source like an inverter on one of the phase wires, it is no longer coordinated with the other source(s) and as a result the current in the neutral can be as much as the sum of the currents in the two phase lines. This can overload the single neutral wire with up to twice its rated current. Not a good idea!

I think the same thing, that I can not join the 2 neutral.. I definitely think I will have to wire everything again .. it is big difficult for me...but for a large project .. i have to work too...

Night Angel you cannot do what you want period. The grid system and off-grid system are required to be completely independent and isolated from each other. They cannot share any common wiring. In fact the wiring of the two systems has to be separated. The only thing in common with them will be the Earth Ground where both systems are referenced together. As I sated earlier Neutral = Grounded Circuit Conductor. So the Earth Ground connection is the only common point the two systems are connected.

yea.. I now... but I wanted an easier solution for my case...

Note that this complete separation is only required if you want to be legal and safe.
Which this forum certainly encourages.

luckily here in Paraguay have no such legal problems! we can do whatever we want!

and the sad thing is that it is a 3rd world country, I can not sell my solar energy...so I'm doing a off-grid, to use our beautiful sun 90% of the year

I also want to mention that our cost of energy is not high .. 0.089us kwh... and we have sometimes grid network failures...and that we have some of the largest world's hydroelectric in my country .. "ITAIPU"
"

thank you all for responding me!

[Sunking]

When you combine systems sharing circuit conductors you will have wished you listened. I am all in when it comes to removing WARNING, HAZARD, and DANGER signs. Takes care of a lot of problems we have today.

[Mike90250]

Looking at the sales ad, they show the outlets (red flag - outlets, not terminals) paralleled, and the chassis ground terminal, tied to ground. Looks like any other mod-square inverter. If you can measure the outlets, the wide blade should have 0 ohms to the chassis ground. If not, you cannot connect to a wired panel that has grounded neutral. (well, you can do it, but you won't be happy with the eventual results) And I see it's a 240V system not a 120V like in the states, so your battery terminals will be floating at 120VAC

Semi-Pure Sine Wave is hype, they have no Harmonic Distortion spec. listed.

[ckchok]

Neutral for Pure Sine Wave Inverter

Hi,

Currently I am using a AC 220V pure sine wave inverter but seems like the neutral having almost 150V ac , and it is not 0V. Under this situation my LED light having the growing effect even when the switch is in OFF position. and it is dangerous too!

I would like to ask, how to make the neutral to 0V, possible?

[SunEagle]

Hi,

Currently I am using a AC 220V pure sine wave inverter but seems like the neutral having almost 150V ac , and it is not 0V. Under this situation my LED light having the growing effect even when the switch is in OFF position. and it is dangerous too!

I would like to ask, how to make the neutral to 0V, possible?

Sounds like you have one of your phase wires in contact with the neutral wire. First I would shut down the inverter and make sure there is no power using a volt meter. Then I would check all of the wiring connections to make sure the phase and neutral wires are separated. Again you can use your meter to check for continuity between phase, neutral and ground wires.

You are correct when you state it is dangerous. Do not use your inverter until you find where the cross connection is.

[inetdog]

Sounds like you have one of your phase wires in contact with the neutral wire. First I would shut down the inverter and make sure there is no power using a volt meter. Then I would check all of the wiring connections to make sure the phase and neutral wires are separated. Again you can use your meter to check for continuity between phase, neutral and ground wires.

You are correct when you state it is dangerous. Do not use your inverter until you find where the cross connection is.

The other possibility is that your inverter has only a two-wire 220 volt output, with no neutral connection. (It may have a third wire for ground, but that is not a neutral.) To derive a center neutral from this output you must get a large enough center-tapped autotransformer. This will allow for load current to flow on either 120 volt circuit alone while drawing equal current from both inverter terminals. You can get such a transformer from Outback, I believe, or find a good enough one locally if you know what to ask for.

What manufacturer and model number is your inverter, so we can check what it is designed to do?

[Sunking]

Hi,

Currently I am using a AC 220V pure sine wave inverter but seems like the neutral having almost 150V ac

How are you measuring this 150 volts. Between what two points?